|
1
|
Quinones MD, Weiman K, Lemon PWR. Ketone Monoester Followed by Carbohydrate Ingestion after Glycogen-Lowering Exercise Does Not Improve Subsequent Endurance Cycle Time Trial Performance. Nutrients 2024; 16:932. [PMID: 38612966 PMCID: PMC11013615 DOI: 10.3390/nu16070932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
Relative to carbohydrate (CHO) alone, exogenous ketones followed by CHO supplementation during recovery from glycogen-lowering exercise have been shown to increase muscle glycogen resynthesis. However, whether this strategy improves subsequent exercise performance is unknown. The objective of this study was to assess the efficacy of ketone monoester (KME) followed by CHO ingestion after glycogen-lowering exercise on subsequent 20 km (TT20km) and 5 km (TT5km) best-effort time trials. Nine recreationally active men (175.6 ± 5.3 cm, 72.9 ± 7.7 kg, 28 ± 5 y, 12.2 ± 3.2% body fat, VO2max = 56.2 ± 5.8 mL· kg BM-1·min-1; mean ± SD) completed a glycogen-lowering exercise session, followed by 4 h of recovery and subsequent TT20km and TT5km. During the first 2 h of recovery, participants ingested either KME (25 g) followed by CHO at a rate of 1.2 g·kg-1·h-1 (KME + CHO) or an iso-energetic placebo (dextrose) followed by CHO (PLAC + CHO). Blood metabolites during recovery and performance during the subsequent two-time trials were measured. In comparison to PLAC + CHO, KME + CHO displayed greater (p < 0.05) blood beta-hydroxybutyrate concentration during the first 2 h, lower (p < 0.05) blood glucose concentrations at 30 and 60 min, as well as greater (p < 0.05) blood insulin concentration 2 h following ingestion. However, no treatment differences (p > 0.05) in power output nor time to complete either time trial were observed vs. PLAC + CHO. These data indicate that the metabolic changes induced by KME + CHO ingestion following glycogen-lowering exercise are insufficient to enhance subsequent endurance time trial performance.
Collapse
Affiliation(s)
| | | | - Peter W. R. Lemon
- Exercise Nutrition Research Laboratory, School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada; (M.D.Q.); (K.W.)
| |
Collapse
|
|
2
|
Magkos F, Reeds DN, Mittendorfer B. Evolution of the diagnostic value of "the sugar of the blood": hitting the sweet spot to identify alterations in glucose dynamics. Physiol Rev 2023; 103:7-30. [PMID: 35635320 PMCID: PMC9576168 DOI: 10.1152/physrev.00015.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/22/2022] Open
Abstract
In this paper, we provide an overview of the evolution of the definition of hyperglycemia during the past century and the alterations in glucose dynamics that cause fasting and postprandial hyperglycemia. We discuss how extensive mechanistic, physiological research into the factors and pathways that regulate the appearance of glucose in the circulation and its uptake and metabolism by tissues and organs has contributed knowledge that has advanced our understanding of different types of hyperglycemia, namely prediabetes and diabetes and their subtypes (impaired fasting plasma glucose, impaired glucose tolerance, combined impaired fasting plasma glucose, impaired glucose tolerance, type 1 diabetes, type 2 diabetes, gestational diabetes mellitus), their relationships with medical complications, and how to prevent and treat hyperglycemia.
Collapse
Affiliation(s)
- Faidon Magkos
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Frederiksberg, Denmark
| | - Dominic N Reeds
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
| | - Bettina Mittendorfer
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
| |
Collapse
|
|
3
|
Zhang X, Cheng Z, Dong S, Rayner C, Wu T, Zhong M, Zhang G, Wang K, Hu S. Effects of ileal glucose infusion on enteropancreatic hormone secretion in humans: relationship to glucose absorption. Metabolism 2022; 131:155198. [PMID: 35395220 DOI: 10.1016/j.metabol.2022.155198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/13/2022] [Accepted: 03/28/2022] [Indexed: 12/12/2022]
Abstract
BACKGROUNDS The distal small intestine plays an important role in regulating the secretion of entero-pancreatic hormones that are critical to the control of glucose metabolism and appetite, but the quantitative contribution of a specific segment to these effects is unknown. PURPOSES To determine the effects of 30 cm of the ileum exposed to glucose on the secretion of ghrelin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) insulin, C-peptide and glucagon, in relation to glucose absorption in non-diabetic subjects. BASIC PROCEDURES 10 non-diabetic subjects with a loop ileostomy after early-stage rectal cancer resection were studied on 2 days in a double-blind, randomized and crossover fashion, when a catheter was inserted retrogradely 30 cm from the ileostomy for infusion of a glucose solution containing 30 g glucose and 3 g 3-O-methylglucose (as a marker of active glucose absorption), or 0.9% saline, over 60 min. Ghrelin, GIP, GLP-1, insulin, C-peptide, glucagon and ileal glucose absorption (from concentrations of 3-O-methylglucose in serum and glucose in ileostomy effluent) were measured over 180 min. MAIN FINDINGS 12.0 ± 1.2 g glucose was absorbed over 180 min. Compared to saline, ileal glucose resulted in minimal increases in blood glucose and plasma insulin and C-peptide, but substantial increases in plasma GLP-1, without affecting ghrelin, GIP or glucagon. The magnitude of the GLP-1 response to glucose was strongly related to the increase in serum 3-O-methylglucose. PRINCIPAL CONCLUSIONS Stimulation of the terminal ileum by glucose, even over a short length (30 cm), induces substantial GLP-1 release, coupled primarily to active glucose absorption. CLINICAL REGISTRATION NCT05030376 (ClinicalTrials.gov).
Collapse
Affiliation(s)
- Xiang Zhang
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Zhiqiang Cheng
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Shuohui Dong
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Christopher Rayner
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, SA, Australia
| | - Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, SA, Australia
| | - Mingwei Zhong
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, China
| | - Guangyong Zhang
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, China
| | - Kexin Wang
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong Province, China.
| | - Sanyuan Hu
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, China; Shandong University, China.
| |
Collapse
|
|
4
|
Hamada N, Wadazumi T, Hirata Y, Watanabe H, Hongu N, Arai N. Effects of Trehalose Solutions at Different Concentrations on High-Intensity Intermittent Exercise Performance. Nutrients 2022; 14:nu14091776. [PMID: 35565744 PMCID: PMC9101545 DOI: 10.3390/nu14091776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/08/2022] [Accepted: 04/20/2022] [Indexed: 11/25/2022] Open
Abstract
Trehalose solution ingested during exercise induces gradual increases in blood glucose levels and the insulin response compared with glucose solution. Trehalose solution aids in the maintenance of performance in the later stages of prolonged exercise. The purpose of this study was to identify the lowest concentration at which the properties of trehalose could be exploited. Groups of 12 healthy men (21.3 ± 1.3 years) and 10 healthy men (21.1 ± 0.7 years) with recreational training were included in experiments 1 and 2, respectively. Both experiments followed the same protocol. After fasting for 12 h, the participants performed a 60 min constant-load exercise at 40% V˙O2 peak using a bicycle ergometer and ingested 500 mL of a trial drink (experiment 1: water, 8% glucose, and 6 or 8% trehalose; experiment 2: 4 or 6% trehalose). They performed four sets of the Wingate test combined with a 30 min constant-load exercise at 40% V˙O2 peak. The experiment was conducted using a randomized cross-over design; trial drink experiments were conducted over intervals of 7 to 12 days. The exercise performance was evaluated based on mean power in the Wingate test. Blood was collected from the fingertip at 12 points during each experiment to measure blood glucose levels. During the high-intensity 5 h intermittent exercise, no differences were found between the groups in exercise performance in the later stages with concentrations of 8, 6, and 4% trehalose solution. The results suggest that trehalose could be useful for making a new type of mixed carbohydrate solution. Further studies to determine the trehalose response of individual athletes during endurance exercise are needed.
Collapse
Affiliation(s)
- Naomi Hamada
- Graduate School of Health and Well-Being, Department of Health and Well-Being, Kansai University, 1-11-1, Kaorigaoka-cho, Sakai-ku, Sakai 590-8515, Osaka, Japan; (T.W.); (Y.H.)
- Department of Applied Food Science, Higashiosaka Junior College, 3-1-1, Nishizutsumigakuen-cho, Higashiosaka 577-8567, Osaka, Japan
- Correspondence: ; Tel.: +81-6-6782-2824
| | - Tsuyoshi Wadazumi
- Graduate School of Health and Well-Being, Department of Health and Well-Being, Kansai University, 1-11-1, Kaorigaoka-cho, Sakai-ku, Sakai 590-8515, Osaka, Japan; (T.W.); (Y.H.)
| | - Yoko Hirata
- Graduate School of Health and Well-Being, Department of Health and Well-Being, Kansai University, 1-11-1, Kaorigaoka-cho, Sakai-ku, Sakai 590-8515, Osaka, Japan; (T.W.); (Y.H.)
- Department of Food and Nutritional Science, Kobe Women’s Junior College, 4-7-2, Nakamachi, Minatojima, Chuo-ku, Kobe 650-0046, Hyogo, Japan
| | - Hitoshi Watanabe
- Research Center for Urban Health and Sports, Osaka Metropolitan University, 3-3-138, Sugimoto, Sumiyoshi-ku 558-8585, Osaka, Japan;
| | - Nobuko Hongu
- Graduate School of Human Life Science, Department of Food and Human Life Science, Osaka Metropolitan University, 3-3-138, Sugimoto, Sumiyoshi-ku 558-8585, Osaka, Japan;
| | - Norie Arai
- Hayashibara, Co., Ltd., 675-1, Fujisaki, Naka-ku 702-8006, Okayama, Japan;
| |
Collapse
|
|
5
|
Matsunaga Y, Takahashi K, Takahashi Y, Hatta H. Effects of glucose ingestion at different frequencies on glycogen recovery in mice during the early hours post exercise. J Int Soc Sports Nutr 2021; 18:69. [PMID: 34743706 PMCID: PMC8574022 DOI: 10.1186/s12970-021-00467-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 10/25/2021] [Indexed: 11/24/2022] Open
Abstract
Background When a high-carbohydrate diet is ingested, whether as small frequent snacks or as large meals, there is no difference between the two with respect to post-exercise glycogen storage for a period of 24 h. However, the effect of carbohydrate intake frequency on glycogen recovery a few hours after exercise is not clear. Athletes need to recover glycogen quickly after physical exercise as they sometimes exercise multiple times a day. The aim of this study was to determine the effect of carbohydrate intake at different frequencies on glycogen recovery during the first few hours after exercise. Methods After 120 min of fasting, 6-week-old male ICR mice were subjected to treadmill running exercise (20 m/min for 60 min) to decrease the levels of muscle and liver glycogen. Mice were then given glucose as a bolus (1.2 mg/g of body weight [BW], immediately after exercise) or as a pulse (1.2 mg/g of BW, every 15 min × 4 times). Following this, the blood, tissue, and exhaled gas samples were collected. Results In the bolus group, blood glucose concentration was significantly lower and plasma insulin concentration was significantly higher than those in the pulse group (p < 0.05). The plantaris muscle glycogen concentration in the bolus group was 25.3% higher than that in the pulse group at 60 min after glucose ingestion (p < 0.05). Liver glycogen concentration in the pulse group was significantly higher than that in the bolus group at 120 min after glucose ingestion (p < 0.05). Conclusions The present study showed that ingesting a large amount of glucose immediately after exercise increased insulin secretion and enhanced muscle glycogen recovery, whereas frequent and small amounts of glucose intake was shown to enhance liver glycogen recovery.
Collapse
Affiliation(s)
- Yutaka Matsunaga
- Department of Sports Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
| | - Kenya Takahashi
- Department of Sports Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Yumiko Takahashi
- Department of Sports Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Hideo Hatta
- Department of Sports Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| |
Collapse
|
|
6
|
Bandegan A, Huang L, Longstaffe FJ, Lemon PW. Dose-Response Oxidation of Ingested Phytoglycogen during Exercise in Endurance-Trained Men. J Nutr 2021; 151:2942-2948. [PMID: 34255078 DOI: 10.1093/jn/nxab219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 05/09/2021] [Accepted: 06/15/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Phytoglycogen (PHY; PhytoSpherix; Mirexus Biotechnologies), a highly branched polysaccharide extracted from sweet corn, has considerable potential for exercise oxidation due to its low viscosity in water, high water retention, and exceptional stability. OBJECTIVES Using gas chromatography-isotope ratio mass spectrometry, we investigated dose-response oxidation of ingested PHY during prolonged, moderate-intensity exercise. METHODS Thirteen men (≥1 y endurance-training experience, ≥6 d·wk-1, ∼1-1.5 h·d-1; age, 25.7 ± 5.5 y; mass, 79.3 ± 10.0 kg; V̇O2max, 59.9 ± 5.5 mL·kg-1·min-1; means ± SDs) cycled for 150 min (50% maximal watt output) while ingesting PHY concentrations of 0.0% (0.0 g·min-1), 3.6% (0.5 g·min-1), 7.2% (1.0 g·min-1), 10.8% (1.5 g·min-1), or 14.4% (2 g·min-1) in water (2100 mL) (n = 7-10/dose). Substrate oxidation was determined using stable-isotope methods and indirect calorimetry. RESULTS PHY oxidation plateaued between 60 and 150 min of exercise and increased (P < 0.001) from 0.49 to 0.72 g·min-1 with 0.5- and 1.0-g·min-1 doses without further increases (0.76 and 0.73 g·min-1; P > 0.05) with 1.5 or 2 g·min-1. Peak PHY oxidation (0.84 ± 0.04 g·min-1) occurred in the final 30 min of exercise with 2 g·min-1. Exercise blood glucose was greater (5.1 mmol·L-1) with 1.0-, 1.5-, and 2-g·min-1 doses compared with that of 0.5 (4.7 mmol·L-1) or 0.0 g·min-1 (4.2 mmol·L-1) (P < 0.0001). Gastrointestinal distress was minimal except with 2 g·min-1 (P < 0.001). CONCLUSIONS In male endurance athletes, PHY oxidation plateaued at 0.72-0.76 g·min-1 during 150 min of cycling at 50% Wmax (peak oxidation of 0.84 g·min-1 occurred during the final 30 min). This trial was registered at clinicaltrials.gov as NCT02909881.
Collapse
Affiliation(s)
- Arash Bandegan
- Exercise Nutrition Research Laboratory, University of Western Ontario, London, Ontario, Canada
| | - Li Huang
- Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada
| | - Fred J Longstaffe
- Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada
| | - Peter Wr Lemon
- Exercise Nutrition Research Laboratory, University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
|
7
|
Wu T, Rayner CK, Jones KL, Xie C, Marathe C, Horowitz M. Role of intestinal glucose absorption in glucose tolerance. Curr Opin Pharmacol 2020; 55:116-124. [PMID: 33227625 DOI: 10.1016/j.coph.2020.10.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/11/2020] [Accepted: 10/19/2020] [Indexed: 02/06/2023]
Abstract
Intestinal glucose absorption is integral to postprandial glucose homeostasis. Glucose absorption is dependent on a number of factors, including the exposure of carbohydrate to the mucosa of the upper gastrointestinal tract (determined particularly by the rates of gastric emptying and small intestinal transit), the digestion of complex carbohydrate into monosaccharides, and glucose sensing and transport by the intestinal mucosa. The absorption of glucose in the small intestine is not only a determinant of the appearance of exogenous glucose in the peripheral circulation, but is also coupled to the release of gastrointestinal hormones that in turn influence postprandial glucose metabolism through modulating gastrointestinal motor function, insulin and glucagon secretion, and subsequent energy intake. This review describes the physiology and pathophysiology of intestinal glucose absorption in health and type 2 diabetes, including its relevance to glucose tolerance and the management of postprandial hyperglycaemia.
Collapse
Affiliation(s)
- Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia; Institute of Diabetes, School of Medicine, Southeast University, Nanjing, China.
| | - Christopher K Rayner
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, Australia
| | - Karen L Jones
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia
| | - Cong Xie
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia
| | - Chinmay Marathe
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia
| | - Michael Horowitz
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia
| |
Collapse
|
|
8
|
Narang BJ, Wallis GA, Gonzalez JT. The effect of calcium co-ingestion on exogenous glucose oxidation during endurance exercise in healthy men: A pilot study. Eur J Sport Sci 2020; 21:1156-1164. [DOI: 10.1080/17461391.2020.1813336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
| | - Gareth A. Wallis
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | | |
Collapse
|
|
9
|
Xie C, Jones KL, Rayner CK, Wu T. Enteroendocrine Hormone Secretion and Metabolic Control: Importance of the Region of the Gut Stimulation. Pharmaceutics 2020; 12:790. [PMID: 32825608 PMCID: PMC7559385 DOI: 10.3390/pharmaceutics12090790] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/19/2020] [Accepted: 08/19/2020] [Indexed: 12/11/2022] Open
Abstract
It is now widely appreciated that gastrointestinal function is central to the regulation of metabolic homeostasis. Following meal ingestion, the delivery of nutrients from the stomach into the small intestine (i.e., gastric emptying) is tightly controlled to optimise their subsequent digestion and absorption. The complex interaction of intraluminal nutrients (and other bioactive compounds, such as bile acids) with the small and large intestine induces the release of an array of gastrointestinal hormones from specialised enteroendocrine cells (EECs) distributed in various regions of the gut, which in turn to regulate gastric emptying, appetite and postprandial glucose metabolism. Stimulation of gastrointestinal hormone secretion, therefore, represents a promising strategy for the management of metabolic disorders, particularly obesity and type 2 diabetes mellitus (T2DM). That EECs are distributed distinctively between the proximal and distal gut suggests that the region of the gut exposed to intraluminal stimuli is of major relevance to the secretion profile of gastrointestinal hormones and associated metabolic responses. This review discusses the process of intestinal digestion and absorption and their impacts on the release of gastrointestinal hormones and the regulation of postprandial metabolism, with an emphasis on the differences between the proximal and distal gut, and implications for the management of obesity and T2DM.
Collapse
Affiliation(s)
- Cong Xie
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide 5005, Australia; (C.X.); (K.L.J.); (C.K.R.)
| | - Karen L. Jones
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide 5005, Australia; (C.X.); (K.L.J.); (C.K.R.)
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide 5005, Australia
| | - Christopher K. Rayner
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide 5005, Australia; (C.X.); (K.L.J.); (C.K.R.)
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide 5005, Australia
| | - Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence (CRE) in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide 5005, Australia; (C.X.); (K.L.J.); (C.K.R.)
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide 5005, Australia
- Institute of Diabetes, School of Medicine, Southeast University, Nanjing 210009, China
| |
Collapse
|
|
10
|
Zhang X, Young RL, Bound M, Hu S, Jones KL, Horowitz M, Rayner CK, Wu T. Comparative Effects of Proximal and Distal Small Intestinal Glucose Exposure on Glycemia, Incretin Hormone Secretion, and the Incretin Effect in Health and Type 2 Diabetes. Diabetes Care 2019; 42:520-528. [PMID: 30765429 DOI: 10.2337/dc18-2156] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 01/16/2019] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Cells releasing glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) are distributed predominately in the proximal and distal gut, respectively. Hence, the region of gut exposed to nutrients may influence GIP and GLP-1 secretion and impact on the incretin effect and gastrointestinal-mediated glucose disposal (GIGD). We evaluated glycemic and incretin responses to glucose administered into the proximal or distal small intestine and quantified the corresponding incretin effect and GIGD in health and type 2 diabetes mellitus (T2DM). RESEARCH DESIGN AND METHODS Ten healthy subjects and 10 patients with T2DM were each studied on four occasions. On two days, a transnasal catheter was positioned with infusion ports opening 13 cm and 190 cm beyond the pylorus, and 30 g glucose with 3 g 3-O-methylglucose (a marker of glucose absorption) was infused into either site and 0.9% saline into the alternate site over 60 min. Matching intravenous isoglycemic clamp studies were performed on the other two days. Blood glucose, serum 3-O-methylglucose, and plasma hormones were evaluated over 180 min. RESULTS In both groups, blood glucose and serum 3-O-methylglucose concentrations were higher after proximal than distal glucose infusion (all P < 0.001). Plasma GLP-1 increased minimally after proximal, but substantially after distal, glucose infusion, whereas GIP increased promptly after both infusions, with concentrations initially greater, but less sustained, with proximal versus distal infusion (all P < 0.001). Both the incretin effect and GIGD were less with proximal than distal glucose infusion (both P ≤ 0.009). CONCLUSIONS The distal, as opposed to proximal, small intestine is superior in modulating postprandial glucose metabolism in both health and T2DM.
Collapse
Affiliation(s)
- Xiang Zhang
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Richard L Young
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Michelle Bound
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - Sanyuan Hu
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Karen L Jones
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Michael Horowitz
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Christopher K Rayner
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - Tongzhi Wu
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Institute of Diabetes, School of Medicine, Southeast University, Nanjing, Jiangsu, China
| |
Collapse
|
|
11
|
Ma J, Vella A. What Has Bariatric Surgery Taught Us About the Role of the Upper Gastrointestinal Tract in the Regulation of Postprandial Glucose Metabolism? Front Endocrinol (Lausanne) 2018; 9:324. [PMID: 29997575 PMCID: PMC6028568 DOI: 10.3389/fendo.2018.00324] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 05/31/2018] [Indexed: 02/06/2023] Open
Abstract
The interaction between the upper gastrointestinal tract and the endocrine system is important in the regulation of metabolism and of weight. The gastrointestinal tract has a heterogeneous cellular content and comprises a variety of cells that elaborate paracrine and endocrine mediators that collectively form the entero-endocrine system. The advent of therapy that utilizes these pathways as well as the association of bariatric surgery with diabetes remission has (re-)kindled interest in the role of the gastrointestinal tract in glucose homeostasis. In this review, we will use the changes wrought by bariatric surgery to provide insights into the various gut-pancreas interactions that maintain weight, regulate satiety, and limit glucose excursions after meal ingestion.
Collapse
Affiliation(s)
- Jing Ma
- Division of Endocrinology and Metabolism, Shanghai Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, NY, United States
| | - Adrian Vella
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, NY, United States
| |
Collapse
|
|
12
|
Gonzalez JT, Fuchs CJ, Betts JA, van Loon LJC. Glucose Plus Fructose Ingestion for Post-Exercise Recovery-Greater than the Sum of Its Parts? Nutrients 2017; 9:E344. [PMID: 28358334 PMCID: PMC5409683 DOI: 10.3390/nu9040344] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/27/2017] [Indexed: 01/24/2023] Open
Abstract
Carbohydrate availability in the form of muscle and liver glycogen is an important determinant of performance during prolonged bouts of moderate- to high-intensity exercise. Therefore, when effective endurance performance is an objective on multiple occasions within a 24-h period, the restoration of endogenous glycogen stores is the principal factor determining recovery. This review considers the role of glucose-fructose co-ingestion on liver and muscle glycogen repletion following prolonged exercise. Glucose and fructose are primarily absorbed by different intestinal transport proteins; by combining the ingestion of glucose with fructose, both transport pathways are utilised, which increases the total capacity for carbohydrate absorption. Moreover, the addition of glucose to fructose ingestion facilitates intestinal fructose absorption via a currently unidentified mechanism. The co-ingestion of glucose and fructose therefore provides faster rates of carbohydrate absorption than the sum of glucose and fructose absorption rates alone. Similar metabolic effects can be achieved via the ingestion of sucrose (a disaccharide of glucose and fructose) because intestinal absorption is unlikely to be limited by sucrose hydrolysis. Carbohydrate ingestion at a rate of ≥1.2 g carbohydrate per kg body mass per hour appears to maximise post-exercise muscle glycogen repletion rates. Providing these carbohydrates in the form of glucose-fructose (sucrose) mixtures does not further enhance muscle glycogen repletion rates over glucose (polymer) ingestion alone. In contrast, liver glycogen repletion rates are approximately doubled with ingestion of glucose-fructose (sucrose) mixtures over isocaloric ingestion of glucose (polymers) alone. Furthermore, glucose plus fructose (sucrose) ingestion alleviates gastrointestinal distress when the ingestion rate approaches or exceeds the capacity for intestinal glucose absorption (~1.2 g/min). Accordingly, when rapid recovery of endogenous glycogen stores is a priority, ingesting glucose-fructose mixtures (or sucrose) at a rate of ≥1.2 g·kg body mass-1·h-1 can enhance glycogen repletion rates whilst also minimising gastrointestinal distress.
Collapse
Affiliation(s)
| | - Cas J Fuchs
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+ (MUMC+), P.O. Box 616, 6200 MD Maastricht, The Netherlands.
| | - James A Betts
- Department for Health, University of Bath, Bath BA2 7AY, UK.
| | - Luc J C van Loon
- Department of Human Biology and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+ (MUMC+), P.O. Box 616, 6200 MD Maastricht, The Netherlands.
| |
Collapse
|
|
13
|
Effects of Bolus and Continuous Nasogastric Feeding on Gastric Emptying, Small Bowel Water Content, Superior Mesenteric Artery Blood Flow, and Plasma Hormone Concentrations in Healthy Adults: A Randomized Crossover Study. Ann Surg 2016; 263:450-7. [PMID: 25549202 PMCID: PMC4741393 DOI: 10.1097/sla.0000000000001110] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE We aimed to demonstrate the effect of continuous or bolus nasogastric feeding on gastric emptying, small bowel water content, and splanchnic blood flow measured by magnetic resonance imaging (MRI) in the context of changes in plasma gastrointestinal hormone secretion. BACKGROUND Nasogastric/nasoenteral tube feeding is often complicated by diarrhea but the contribution of feeding strategy to the etiology is unclear. METHODS Twelve healthy adult male participants who underwent nasogastric intubation before a baseline MRI scan, received 400 mL of Resource Energy (Nestle) as a bolus over 5 minutes or continuously over 4 hours via pump in this randomized crossover study. Changes in gastric volume, small bowel water content, and superior mesenteric artery blood flow and velocity were measured over 4 hours using MRI and blood glucose and plasma concentrations of insulin, peptide YY, and ghrelin were assayed every 30 minutes. RESULTS Bolus nasogastric feeding led to significant elevations in gastric volume (P < 0.0001), superior mesenteric artery blood flow (P < 0.0001), and velocity (P = 0.0011) compared with continuous feeding. Both types of feeding reduced small bowel water content, although there was an increase in small bowel water content with bolus feeding after 90 minutes (P < 0.0068). Similarly, both types of feeding led to a fall in plasma ghrelin concentration although this fall was greater with bolus feeding (P < 0.0001). Bolus feeding also led to an increase in concentrations of insulin (P = 0.0024) and peptide YY (P < 0.0001), not seen with continuous feeding. CONCLUSION Continuous nasogastric feeding does not increase small bowel water content, thus fluid flux within the small bowel is not a major contributor to the etiology of tube feeding-related diarrhea.
Collapse
|
|
14
|
Svihus B, Hervik AK. Digestion and metabolic fates of starch, and its relation to major nutrition-related health problems: A review. STARCH-STARKE 2016. [DOI: 10.1002/star.201500295] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
|
15
|
Fructose–Glucose Composite Carbohydrates and Endurance Performance: Critical Review and Future Perspectives. Sports Med 2015; 45:1561-76. [DOI: 10.1007/s40279-015-0381-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
|
16
|
Stocks B, Betts JA, McGawley K. Effects of carbohydrate dose and frequency on metabolism, gastrointestinal discomfort, and cross-country skiing performance. Scand J Med Sci Sports 2015; 26:1100-8. [PMID: 26316418 DOI: 10.1111/sms.12544] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2015] [Indexed: 11/29/2022]
Abstract
This study investigated carbohydrate ingestion of varied doses and frequencies during a simulated cross-country skiing time trial. Ten men and three women (age: 30 ± 7 years; V ˙ O 2 m a x : 59.6 ± 5.7 mL/kg/min) completed four, 30-km classic technique roller skiing time trials on a treadmill. A 1:1 maltodextrin-fructose carbohydrate solution was provided at high (2.4 g/min; HC) and moderate (1.2 g/min; MC) ingestion rates, each at high (six feeds; HF) and low (two feeds; LF) frequencies. In the LF trials, blood glucose was elevated following carbohydrate ingestion (at 4 and 19 km) but was reduced at 14 and 29 km compared with HF strategies (P ≤ 0.05). Gastrointestinal discomfort was higher in HC-LF compared with all other trials (P ≤ 0.05). Whole-body lipid oxidation was lower and carbohydrate oxidation was higher in LF compared with HF trials (P ≤ 0.05). While performance time was not significantly different between trials (140:11 ± 15:31, 140:43 ± 17:40, 139:12 ± 15:32 and 140:33 ± 17:46 min:s in HC-HF, HC-LF, MC-HF, and MC-LF, respectively; P > 0.05), it was improved with trial order (P < 0.001). There was no effect of order on any other variable (P > 0.05). Altering carbohydrate dose or frequency does not affect cross-country ski performance. However, low-frequency carbohydrate ingestion resulted in poorer maintenance of euglycemia, reduced lipid oxidation, and increased gastrointestinal discomfort.
Collapse
Affiliation(s)
- B Stocks
- Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.,Human Physiology Research Group, Department for Health, University of Bath, Bath, UK
| | - J A Betts
- Human Physiology Research Group, Department for Health, University of Bath, Bath, UK
| | - K McGawley
- Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| |
Collapse
|
|
17
|
|
|
18
|
Wu T, Thazhath SS, Marathe CS, Bound MJ, Jones KL, Horowitz M, Rayner CK. Comparative effect of intraduodenal and intrajejunal glucose infusion on the gut-incretin axis response in healthy males. Nutr Diabetes 2015; 5:e156. [PMID: 25985092 PMCID: PMC4450461 DOI: 10.1038/nutd.2015.6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/22/2015] [Accepted: 04/05/2015] [Indexed: 02/07/2023] Open
Abstract
The region of enteral nutrient exposure may be an important determinant of postprandial incretin hormone secretion and blood glucose homoeostasis. We compared responses of plasma glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), insulin and glucagon, and blood glucose to a standardised glucose infusion into the proximal jejunum and duodenum in healthy humans. Ten healthy males were evaluated during a standardised glucose infusion (2 kcal min(-1) over 120 min) into the proximal jejunum (50 cm post pylorus) and were compared with another 10 healthy males matched for ethnicity, age and body mass index who received an identical glucose infusion into the duodenum (12 cm post pylorus). Blood was sampled frequently for measurements of blood glucose and plasma hormones. Plasma GLP-1, GIP and insulin responses, as well as the insulin:glucose ratio and the insulinogenic index 1 (IGI1) were greater (P<0.05 for each) after intrajejunal (i.j.) than intraduodenal glucose infusion, without a significant difference in blood glucose or plasma glucagon. Pooled analyses revealed direct relationships between IGI1 and the responses of GLP-1 and GIP (r=0.48 and 0.56, respectively, P<0.05 each), and between glucagon and GLP-1 (r=0.70, P<0.001). In conclusion, i.j. glucose elicits greater incretin hormone and insulin secretion than intraduodenal glucose in healthy humans, suggesting regional specificity of the gut-incretin axis.
Collapse
Affiliation(s)
- T Wu
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - S S Thazhath
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - C S Marathe
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - M J Bound
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - K L Jones
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - M Horowitz
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| | - C K Rayner
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, The University of Adelaide, Adelaide, South Australia, Australia
| |
Collapse
|
|
19
|
Phillips LK, Deane AM, Jones KL, Rayner CK, Horowitz M. Gastric emptying and glycaemia in health and diabetes mellitus. Nat Rev Endocrinol 2015; 11:112-128. [PMID: 25421372 DOI: 10.1038/nrendo.2014.202] [Citation(s) in RCA: 194] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The rate of gastric emptying is a critical determinant of postprandial glycaemia and, accordingly, is fundamental to maintaining blood glucose homeostasis. Disordered gastric emptying occurs frequently in patients with longstanding type 1 diabetes mellitus and type 2 diabetes mellitus (T2DM). A complex bidirectional relationship exists between gastric emptying and glycaemia--gastric emptying accounts for ∼35% of the variance in peak postprandial blood glucose concentrations in healthy individuals and in patients with diabetes mellitus, and the rate of emptying is itself modulated by acute changes in glycaemia. Clinical implementation of incretin-based therapies for the management of T2DM, which diminish postprandial glycaemia, in part by slowing gastric emptying, is widespread. Other therapies for patients with T2DM, which specifically target gastric emptying include pramlintide and dietary-based treatment approaches. A weak association exists between upper gastrointestinal symptoms and the rate of gastric emptying. In patients with severe diabetic gastroparesis, pathological changes are highly variable and are characterized by loss of interstitial cells of Cajal and an immune infiltrate. Management options for patients with symptomatic gastroparesis remain limited in their efficacy, which probably reflects the heterogeneous nature of the underlying pathophysiology.
Collapse
Affiliation(s)
- Liza K Phillips
- Centre of Research Excellence in Translating Nutritional Science to Good Health, Discipline of Medicine, The University of Adelaide, Level 6 Eleanor Harrald Building, Royal Adelaide Hospital, Frome Road, Adelaide, SA 5005, Australia
| | - Adam M Deane
- Centre of Research Excellence in Translating Nutritional Science to Good Health, Discipline of Medicine, The University of Adelaide, Level 6 Eleanor Harrald Building, Royal Adelaide Hospital, Frome Road, Adelaide, SA 5005, Australia
| | - Karen L Jones
- Centre of Research Excellence in Translating Nutritional Science to Good Health, Discipline of Medicine, The University of Adelaide, Level 6 Eleanor Harrald Building, Royal Adelaide Hospital, Frome Road, Adelaide, SA 5005, Australia
| | - Chris K Rayner
- Centre of Research Excellence in Translating Nutritional Science to Good Health, Discipline of Medicine, The University of Adelaide, Level 6 Eleanor Harrald Building, Royal Adelaide Hospital, Frome Road, Adelaide, SA 5005, Australia
| | - Michael Horowitz
- Centre of Research Excellence in Translating Nutritional Science to Good Health, Discipline of Medicine, The University of Adelaide, Level 6 Eleanor Harrald Building, Royal Adelaide Hospital, Frome Road, Adelaide, SA 5005, Australia
| |
Collapse
|
|
20
|
Slater G, Rice A, Jenkins D, Hahn A. Body mass management of lightweight rowers: nutritional strategies and performance implications. Br J Sports Med 2014; 48:1529-33. [DOI: 10.1136/bjsports-2014-093918] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
|
21
|
Sugar flux through the flight muscles of hovering vertebrate nectarivores: a review. J Comp Physiol B 2014; 184:945-59. [PMID: 25031038 DOI: 10.1007/s00360-014-0843-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/15/2014] [Accepted: 06/20/2014] [Indexed: 12/28/2022]
Abstract
In most vertebrates, uptake and oxidation of circulating sugars by locomotor muscles rises with increasing exercise intensity. However, uptake rate by muscle plateaus at moderate aerobic exercise intensities and intracellular fuels dominate at oxygen consumption rates of 50% of maximum or more. Further, uptake and oxidation of circulating fructose by muscle is negligible. In contrast, hummingbirds and nectar bats are capable of fueling expensive hovering flight exclusively, or nearly completely, with dietary sugar. In addition, hummingbirds and nectar bats appear capable of fueling hovering flight completely with fructose. Three crucial steps are believed to be rate limiting to muscle uptake of circulating glucose or fructose in vertebrates: (1) delivery to muscle; (2) transport into muscle through glucose transporter proteins (GLUTs); and (3) phosphorylation of glucose by hexokinase (HK) within the muscle. In this review, we summarize what is known about the functional upregulation of exogenous sugar flux at each of these steps in hummingbirds and nectar bats. High cardiac output, capillary density, and blood sugar levels in hummingbirds and bats enhance sugar delivery to muscles (step 1). Hummingbird and nectar bat flight muscle fibers have relatively small cross-sectional areas and thus relatively high surface areas across which transport can occur (step 2). Maximum HK activities in each species are enough for carbohydrate flux through glycolysis to satisfy 100 % of hovering oxidative demand (step 3). However, qualitative patterns of GLUT expression in the muscle (step 2) raise more questions than they answer regarding sugar transport in hummingbirds and suggest major differences in the regulation of sugar flux compared to nectar bats. Behavioral and physiological similarities among hummingbirds, nectar bats, and other vertebrates suggest enhanced capacities for exogenous fuel use during exercise may be more wide spread than previously appreciated. Further, how the capacity for uptake and phosphorylation of circulating fructose is enhanced remains a tantalizing unknown.
Collapse
|
|
22
|
O'Brien WJ, Stannard SR, Clarke JA, Rowlands DS. Fructose-maltodextrin ratio governs exogenous and other CHO oxidation and performance. Med Sci Sports Exerc 2014; 45:1814-24. [PMID: 23949097 DOI: 10.1249/mss.0b013e31828e12d4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Fructose coingested with glucose in carbohydrate (CHO) drinks increases exogenous-CHO oxidation, gut comfort, and physical performance. PURPOSE This study aimed to determine the effect of different fructose-maltodextrin-glucose ratios on CHO oxidation and fluid absorption while controlling for osmolality and caloricity. METHODS In a crossover design, 12 male cyclists rode 2 h at 57% peak power then performed 10 sprints while ingesting artificially sweetened water or three equiosmotic 11.25% CHO-salt drinks at 200 mL·15 min, comprising weighed fructose and maltodextrin-glucose in ratios of 0.5:1 (0.5 ratio), 0.8:1 (0.8 ratio), and 1.25:1 (1.25 ratio). Fluid absorption was traced with D2O, whereas C-fructose and C-maltodextrin-glucose permitted fructose and glucose oxidation rate evaluation. RESULTS The mean exogenous-fructose and exogenous-glucose oxidation rates were 0.27, 0.39, and 0.46 g·min and 0.65, 0.71, and 0.58 g·min in 0.5, 0.8, and 1.25 ratio drinks, representing mean oxidation efficiencies of 54%, 59%, and 55% and 65%, 85%, and 86% for fructose and glucose, respectively. With the 0.8 ratio drink, total exogenous-CHO oxidation rate was 18% (90% confidence interval, ±5%) and 5.2% (±4.6%) higher relative to 0.5 and 1.25 ratios, respectively, whereas respective differences in total exogenous-CHO oxidation efficiency were 17% (±5%) and 5.3% (±4.8%), associated with 8.6% and 7.8% (±4.2%) higher fructose oxidation efficiency. The effects of CHO ratio on water absorption were inconclusive. Mean sprint power with the 0.8 ratio drink was moderately higher than that with the 0.5 ratio (2.9%; 99% confidence interval, ±2.8%) and 1.25 ratio (3.1%; ±2.7%) drinks, with total- and endogenous-CHO oxidation rate, abdominal cramps, and drink sweetness qualifying as explanatory mechanisms. CONCLUSIONS Enhanced high-intensity endurance performance with a 0.8 ratio fructose-maltodextrin-glucose drink is characterized by higher exogenous-CHO oxidation efficiency and reduced endogenous-CHO oxidation. The gut-hepatic or other physiological site responsible requires further research.
Collapse
Affiliation(s)
- Wendy J O'Brien
- School of Sport and Exercise, Massey University, Wellington, New Zealand
| | | | | | | |
Collapse
|
|
23
|
Thazhath SS, Wu T, Young RL, Horowitz M, Rayner CK. Glucose absorption in small intestinal diseases. Expert Rev Gastroenterol Hepatol 2014; 8:301-312. [PMID: 24502537 DOI: 10.1586/17474124.2014.887439] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recent developments in the field of diabetes and obesity management have established the central role of the gut in glucose homeostasis; not only is the gut the primary absorptive site, but it also triggers neurohumoral feedback responses that regulate the pre- and post-absorptive phases of glucose metabolism. Structural and/or functional disorders of the intestine have the capacity to enhance (e.g.: diabetes) or inhibit (e.g.: short-gut syndrome, critical illness) glucose absorption, with potentially detrimental outcomes. In this review, we first describe the normal physiology of glucose absorption and outline the methods by which it can be quantified. Then we focus on the structural and functional changes in the small intestine associated with obesity, critical illness, short gut syndrome and other malabsorptive states, and particularly Type 2 diabetes, which can impact upon carbohydrate absorption and overall glucose homeostasis.
Collapse
Affiliation(s)
- Sony S Thazhath
- Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, SA, Australia
| | | | | | | | | |
Collapse
|
|
24
|
High-fat diet ingestion correlates with neuropathy in the duodenum myenteric plexus of obese mice with symptoms of type 2 diabetes. Cell Tissue Res 2013; 354:381-94. [PMID: 23881404 DOI: 10.1007/s00441-013-1681-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 06/13/2013] [Indexed: 02/08/2023]
Abstract
Obesity and type 2 diabetes are increasing in prevalence at an alarming rate in developed and developing nations and over 50% of patients with prolonged stages of disease experience forms of autonomic neuropathy. These patients have symptoms indicating disrupted enteric nervous system function including gastric discomfort, gastroparesis and intestinal dysmotility. Previous assessments have examined enteric neuronal injury within either type 1 diabetic or transgenic type 2 diabetic context. This study aims to assess damage to myenteric neurons within the duodenum of high-fat diet ingesting mice experiencing symptoms of type 2 diabetes, as this disease context is most parallel to the human condition and disrupted duodenal motility underlies negative gastrointestinal symptoms. Mice fed a high-fat diet developed symptoms of obesity and diabetes by 4 weeks. After 8 weeks, the total number of duodenal myenteric neurons and the synaptophysin density index were reduced and transmission electron microscopy showed axonal swelling and loss of neurofilaments and microtubules, suggesting compromised neuronal health. High-fat diet ingestion correlated with a loss of neurons expressing VIP and nNOS but did not affect the expression of ChAT, substance P, calbindin and CGRP. These results correlate high-fat diet ingestion, obesity and type 2 diabetes symptoms with a loss of duodenal neurons, biasing towards those with inhibitory nature. This pathology may underlie dysmotility and other negative GI symptoms experienced by human type 2 diabetic and obese patients.
Collapse
|
|
25
|
O'Brien WJ, Rowlands DS. Fructose-maltodextrin ratio in a carbohydrate-electrolyte solution differentially affects exogenous carbohydrate oxidation rate, gut comfort, and performance. Am J Physiol Gastrointest Liver Physiol 2011; 300:G181-9. [PMID: 21071509 DOI: 10.1152/ajpgi.00419.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Solutions containing multiple carbohydrates utilizing different intestinal transporters (glucose and fructose) show enhanced absorption, oxidation, and performance compared with single-carbohydrate solutions, but the impact of the ratio of these carbohydrates on outcomes is unknown. In a randomized double-blind crossover, 10 cyclists rode 150 min at 50% peak power, then performed an incremental test to exhaustion, while ingesting artificially sweetened water or one of three carbohydrate-salt solutions comprising fructose and maltodextrin in the respective following concentrations: 4.5 and 9% (0.5-Ratio), 6 and 7.5% (0.8-Ratio), and 7.5 and 6% (1.25-Ratio). The carbohydrates were ingested at 1.8 g/min and naturally (13)C-enriched to permit evaluation of oxidation rate by mass spectrometry and indirect calorimetry. Mean exogenous carbohydrate oxidation rates were 1.04, 1.14, and 1.05 g/min (coefficient of variation 20%) in 0.5-, 0.8-, and 1.25-Ratios, respectively, representing likely small increases in 0.8-Ratio of 11% (90% confidence limits; ± 4%) and 10% (± 4%) relative to 0.5- and 1.25-Ratios, respectively. Comparisons of fat and total and endogenous carbohydrate oxidation rates between solutions were unclear. Relative to 0.5-Ratio, there were moderate improvements to peak power with 0.8- (3.6%; 99% confidence limits ± 3.5%) and 1.25-Ratio (3.0%; ± 3.7%) but unclear with water (0.4%; ± 4.4%). Increases in stomach fullness, abdominal cramping, and nausea were lowest with the 0.8- followed by the 1.25-Ratio solution. At high carbohydrate-ingestion rate, greater benefits to endurance performance may result from ingestion of 0.8- to 1.25-Ratio fructose-maltodextrin solutions. Small perceptible improvements in gut comfort favor the 0.8-Ratio and provide a clearer suggestion of mechanism than the relationship with exogenous carbohydrate oxidation.
Collapse
Affiliation(s)
- Wendy J O'Brien
- School of Sport and Exercise, Massey University, Wellington, New Zealand
| | | |
Collapse
|
|
26
|
Byars A, Keith S, Simpson W, Mooneyhan A, Greenwood M. The influence of a pre-exercise sports drink (PRX) on factors related to maximal aerobic performance. J Int Soc Sports Nutr 2010; 7:12. [PMID: 20222976 PMCID: PMC2845094 DOI: 10.1186/1550-2783-7-12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 03/11/2010] [Indexed: 01/11/2023] Open
Abstract
Background Pre-exercise sports drinks (PRX) are commonly used as ergogenic aids in athletic competitions requiring aerobic power. However, in most cases, claims regarding their effectiveness have not been substantiated. In addition, the ingredients in PRX products must be deemed acceptable by the athletic governing bodies that regulate their use in training and competition. The purpose of this study was to examine the effects of a modified PRX formulation (known as EM·PACT™) from earlier investigations on factors related to maximal aerobic performance during a graded exercise test. The modification consisted of removing creatine to meet the compliance standards set forth by various athletic organizations that regulate the use of nutritional supplements. Methods Twenty-nine male and female college students varying in levels of aerobic fitness participated in a randomized crossover administration of PRX (containing 14 g/serving of fructose, medium-chain triglycerides, and amino acids mixed with 8 oz. of water) and placebo (PL) 30 minutes prior to performing a treadmill test with approximately one week separation between the trials. VO2max, maximal heart rate (HR), time to exhaustion (Time), and percentage estimated non-protein fat substrate utilization (FA) during two a priori submaximal stages of a graded exercise testing were evaluated. Results The VO2max mean value of the PRX trial was significantly greater than the PL trial (P < 0.01). The mean value for Time was also observed to be greater for the PRX trial compared to PL (P < 0.05). Additionally, percentage of FA during submaximal stages of the exercise test was greater for PRX trial in comparison to PL (P < 0.01). Conclusions The modified PRX formulation utilized in this investigation supports the findings of the previous investigation and its efficacy for enhancing indices of aerobic performance (specifically VO2max, Time, & FA) during graded exercise testing.
Collapse
Affiliation(s)
- Allyn Byars
- Department of Kinesiology, Angelo State University, San Angelo, TX 76909, USA.
| | | | | | | | | |
Collapse
|
|
27
|
Jeukendrup AE, Moseley L. Multiple transportable carbohydrates enhance gastric emptying and fluid delivery. Scand J Med Sci Sports 2010; 20:112-21. [DOI: 10.1111/j.1600-0838.2008.00862.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
|
28
|
Ma J, Rayner CK, Jones KL, Horowitz M. Insulin secretion in healthy subjects and patients with Type 2 diabetes--role of the gastrointestinal tract. Best Pract Res Clin Endocrinol Metab 2009; 23:413-424. [PMID: 19748059 DOI: 10.1016/j.beem.2009.03.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Postprandial glycaemia is now recognised as the major determinant of average glycaemic control in type 2 diabetes, as assessed by glycated haemoglobin. Therefore, an understanding of the factors influencing both the rise in blood glucose and insulin secretion after a meal is fundamental to the development of dietary and pharmacological approaches to optimise glycaemic control. The gastrointestinal tract regulates the rate at which carbohydrate and other nutrients are absorbed and is the source of regulatory peptides that stimulate pancreatic insulin secretion in the setting of elevated blood glucose levels. This article highlights the importance of the gastrointestinal tract in insulin secretion and glucose homeostasis and discusses potential strategies directed at modification of gastrointestinal function in order to improve glycaemic control in the management of diabetes.
Collapse
Affiliation(s)
- Jing Ma
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide, SA, Australia
| | | | | | | |
Collapse
|
|
29
|
Lacerda ACR, Alecrim P, Damasceno WC, Gripp F, Pinto KMC, Silami-Garcia E. Carbohydrate Ingestion During Exercise Does Not Delay the Onset of Fatigue During Submaximal Cycle Exercise. J Strength Cond Res 2009; 23:1276-81. [DOI: 10.1519/jsc.0b013e3181965ddc] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
|
30
|
Chaikomin R, Wu KL, Doran S, Meyer JH, Jones KL, Feinle-Bisset C, Horowitz M, Rayner CK. Effects of mid-jejunal compared to duodenal glucose infusion on peptide hormone release and appetite in healthy men. REGULATORY PEPTIDES 2008; 150:38-42. [PMID: 18396340 DOI: 10.1016/j.regpep.2008.02.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 02/11/2008] [Accepted: 02/15/2008] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Cells containing GIP and CCK predominate in the upper small intestine, while those containing GLP-1 are located more distally. Our aim was to compare the hormonal, glycemic and appetite responses to different sites of glucose delivery. METHODS Ten healthy males were each studied twice, in randomized order. A catheter was positioned with openings 15 cm beyond the pylorus ("duodenal"), and 100 cm beyond ("mid-jejunal"). On one day, glucose was infused into the duodenum (1 kcal/min) and saline into the mid-jejunum, for 90 min. On the other day, the infusion sites were reversed. Blood was sampled frequently, and hunger was scored by questionnaires. The tube was removed and energy intake measured from a buffet meal. RESULTS Stimulation of CCK and suppression of hunger were greater (each P<0.05), and energy intake less (P=0.05), with duodenal compared to mid-jejunal glucose infusion. Blood glucose, GIP, and insulin did not differ, and there was minimal GLP-1 increment on either day. CONCLUSIONS There is regional variation in CCK, but not incretin hormone release, in the upper small intestine, and modest differences in the site of glucose exposure affect appetite and energy intake.
Collapse
Affiliation(s)
- Reawika Chaikomin
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide, Australia
| | | | | | | | | | | | | | | |
Collapse
|
|
31
|
Clarke ND, Drust B, Maclaren DPM, Reilly T. Fluid provision and metabolic responses to soccer-specific exercise. Eur J Appl Physiol 2008; 104:1069-77. [PMID: 18781319 DOI: 10.1007/s00421-008-0864-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2008] [Indexed: 11/30/2022]
Abstract
The present study aimed to investigate the impact on metabolism of altering the timing and volume of ingested carbohydrate during soccer-specific exercise. Twelve soccer players performed a soccer-specific protocol on three occasions. On two, 7 ml kg(-1) carbohydrate-electrolyte or placebo were ingested at 0 and 45 min. On a third, the same total volume of carbohydrate-electrolyte was consumed but at 0, 15, 30, 45, 60 and 75 min. Carbohydrate-electrolyte ingestion increased blood glucose, insulin and carbohydrate oxidation, whilst suppressing NEFA, glycerol and fat oxidation (P < 0.05) although manipulating the schedule of carbohydrate ingestion elicited similar metabolic responses (P > 0.05). However, consuming fluid in small volumes reduced the sensation of gut fullness (P < 0.05). The results demonstrated that when the total volume of carbohydrate consumed is equal, manipulating the timing and volume of ingestion elicits similar metabolic responses. Furthermore, consuming a small volume of fluid at regular intervals reduces the sensation of gut fullness.
Collapse
Affiliation(s)
- N D Clarke
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Henry Cotton Campus, 15-21 Webster Street, Liverpool L3 2ET, UK.
| | | | | | | |
Collapse
|
|
32
|
Pilichiewicz AN, Chaikomin R, Brennan IM, Wishart JM, Rayner CK, Jones KL, Smout AJPM, Horowitz M, Feinle-Bisset C. Load-dependent effects of duodenal glucose on glycemia, gastrointestinal hormones, antropyloroduodenal motility, and energy intake in healthy men. Am J Physiol Endocrinol Metab 2007; 293:E743-E753. [PMID: 17609258 DOI: 10.1152/ajpendo.00159.2007] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Gastric emptying is a major determinant of glycemia, gastrointestinal hormone release, and appetite. We determined the effects of different intraduodenal glucose loads on glycemia, insulinemia, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and cholecystokinin (CCK), antropyloroduodenal motility, and energy intake in healthy subjects. Blood glucose, plasma hormone, and antropyloroduodenal motor responses to 120-min intraduodenal infusions of glucose at 1) 1 ("G1"), 2) 2 ("G2"), and 3) 4 ("G4") kcal/min or of 4) saline ("control") were measured in 10 healthy males in double-blind, randomized fashion. Immediately after each infusion, energy intake at a buffet meal was quantified. Blood glucose rose in response to all glucose infusions (P < 0.05 vs. control), with the effect of G4 and G2 being greater than that of G1 (P < 0.05) but with no difference between G2 and G4. The rises in insulin, GLP-1, GIP, and CCK were related to the glucose load (r > 0.82, P < 0.05). All glucose infusions suppressed antral (P < 0.05), but only G4 decreased duodenal, pressure waves (P < 0.01), resulted in a sustained stimulation of basal pyloric pressure (P < 0.01), and decreased energy intake (P < 0.05). In conclusion, variations in duodenal glucose loads have differential effects on blood glucose, plasma insulin, GLP-1, GIP and CCK, antropyloroduodenal motility, and energy intake in healthy subjects. These observations have implications for strategies to minimize postprandial glycemic excursions in type 2 diabetes.
Collapse
Affiliation(s)
- Amelia N Pilichiewicz
- University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide SA 5000, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
|
33
|
Chaikomin R, Wu KL, Doran S, Jones KL, Smout AJPM, Renooij W, Holloway RH, Meyer JH, Horowitz M, Rayner CK. Concurrent duodenal manometric and impedance recording to evaluate the effects of hyoscine on motility and flow events, glucose absorption, and incretin release. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1099-G1104. [PMID: 17204542 DOI: 10.1152/ajpgi.00519.2006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Upper gastrointestinal motor function and incretin hormone secretion are major determinants of postprandial glycemia and insulinemia. However, the impact of small intestinal flow events on glucose absorption and incretin release is poorly defined. Intraluminal impedance monitoring is a novel technique that allows flow events to be quantified. Eight healthy volunteers were studied twice, in random order. A catheter incorporating six pairs of electrodes at 3-cm intervals, and six corresponding manometry sideholes, was positioned in the duodenum. Hyoscine butylbromide (20 mg) or saline was given as an intravenous bolus, followed by a continuous intravenous infusion of either hyoscine (20 mg/h) or saline over 60 min. Concurrently, glucose and 3-O-methylglucose (3-OMG) were infused into the proximal duodenum (3 kcal/min), with frequent blood sampling to measure glucose, 3-OMG, insulin, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). The frequency of duodenal pressure waves and propagated pressure wave sequences was reduced by hyoscine in the first 10 min (P<0.01 for both), but not after that time. In contrast, there were markedly fewer duodenal flow events throughout 60 min with hyoscine (P<0.005). Overall, blood glucose (P<0.01) and plasma 3-OMG concentrations (P<0.05) were lower during hyoscine than saline, whereas plasma insulin, GLP-1, and GIP concentrations were initially (t=20 min) lower during hyoscine (P<0.05). In conclusion, intraluminal impedance measurement may be more sensitive than manometry in demonstrating alterations in duodenal motor function. A reduction in the frequency of duodenal flow events is associated with a decreased rate of glucose absorption and incretin release in healthy subjects.
Collapse
Affiliation(s)
- Reawika Chaikomin
- Discipline of Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, SA, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
|
34
|
Chaikomin R, Rayner CK, Jones KL, Horowitz M. Upper gastrointestinal function and glycemic control in diabetes mellitus. World J Gastroenterol 2006; 12:5611-5621. [PMID: 17007012 PMCID: PMC4088160 DOI: 10.3748/wjg.v12.i35.5611] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 06/06/2006] [Accepted: 06/16/2006] [Indexed: 02/06/2023] Open
Abstract
Recent evidence has highlighted the impact of glycemic control on the incidence and progression of diabetic micro- and macrovascular complications, and on cardiovascular risk in the non-diabetic population. Postprandial blood glucose concentrations make a major contribution to overall glycemic control, and are determined in part by upper gastrointestinal function. Conversely, poor glycemic control has an acute, reversible effect on gastrointestinal motility. Insights into the mechanisms by which the gut contributes to glycemia have given rise to a number of novel dietary and pharmacological strategies designed to lower postprandial blood glucose concentrations.
Collapse
Affiliation(s)
- Reawika Chaikomin
- Department of Medicine, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia 5000, Australia
| | | | | | | |
Collapse
|
|
35
|
Rowlands DS, Wallis GA, Shaw C, Jentjens RLPG, Jeukendrup AE. Glucose Polymer Molecular Weight Does Not Affect Exogenous Carbohydrate Oxidation. Med Sci Sports Exerc 2005; 37:1510-6. [PMID: 16177602 DOI: 10.1249/01.mss.0000177586.68399.f5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To compare the effects of high (HMW) versus low molecular weight (LMW) glucose polymer solutions on the pattern of substrate oxidation during exercise. METHODS Eight cyclists (VO(2max): 63 +/- 8 mL.kg(-1).min(-1)) performed three 150-min cycling trials at 64 +/- 5% VO(2max) while ingesting 11.25% HMW (500-750 kg.mol(-1), 21 mOsm.kg(-1)) or LMW (8 kg.mol(-1), 110 mOsm.kg(-1)) solutions providing 1.8 g of carbohydrate per minute, or plain water. Substrate oxidation was determined using stable-isotope methods and indirect calorimetry. RESULTS Exogenous carbohydrate oxidation rate was not affected by carbohydrate molecular weight (P = 0.89, peak rate: 0.93 x// 1.37 g.min(-1)). There was no effect of carbohydrate molecular weight on endogenous carbohydrate or fat oxidation rates (P = 0.30), plasma free fatty acid (P = 0.14), lactate (P = 0.38), or glucose concentrations (P = 0.98), nor were there any serious gastrointestinal complaints reported for either of the two solutions during exercise. CONCLUSIONS Despite previous reports of faster gastric emptying and glycogen resynthesis suggesting enhanced glucose delivery, a markedly hypotonic HMW glucose polymer solution had no effect on exogenous and endogenous substrate oxidation rates during exercise, relative to a LMW glucose polymer solution. These data are consistent with there being no effect of carbohydrate structure or solution osmolality or viscosity on exogenous glucose oxidation and that ingested glucose polymers can only be oxidized on average up to 1.0 g.min during exercise.
Collapse
Affiliation(s)
- David S Rowlands
- Institute of Food, Nutrition, and Human Health, Massey University, Wellington, New Zealand.
| | | | | | | | | |
Collapse
|
|
36
|
Wallis GA, Rowlands DS, Shaw C, Jentjens RLPG, Jeukendrup AE. Oxidation of combined ingestion of maltodextrins and fructose during exercise. Med Sci Sports Exerc 2005; 37:426-32. [PMID: 15741841 DOI: 10.1249/01.mss.0000155399.23358.82] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To determine whether combined ingestion of maltodextrin and fructose during 150 min of cycling exercise would lead to exogenous carbohydrate oxidation rates higher than 1.1 g.min. METHODS Eight trained cyclists VO2max: 64.1 +/- 3.1 mL.kg.min) performed three exercise trials in a random order. Each trial consisted of 150 min cycling at 55% maximum power output (64.2+/-3.5% VO2max) while subjects received a solution providing either 1.8 g.min of maltodextrin (MD), 1.2 g.min of maltodextrin + 0.6 g.min of fructose (MD+F), or plain water. To quantify exogenous carbohydrate oxidation, corn-derived MD and F were used, which have a high natural abundance of C. RESULTS Peak exogenous carbohydrate oxidation (last 30 min of exercise) rates were approximately 40% higher with combined MD+F ingestion compared with MD only ingestion (1.50+/-0.07 and 1.06+/-0.08 g.min, respectively, P<0.05). Furthermore, the average exogenous carbohydrate oxidation rate during the last 90 min of exercise was higher with combined MD+F ingestion compared with MD alone (1.38+/-0.06 and 0.96+/-0.07 g.min, respectively, P<0.05). CONCLUSIONS The present study demonstrates that with ingestion of large amounts of maltodextrin and fructose during cycling exercise, exogenous carbohydrate oxidation can reach peak values of approximately 1.5 g.min, and this is markedly higher than oxidation rates from ingesting maltodextrin alone.
Collapse
Affiliation(s)
- Gareth A Wallis
- School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UNITED KINGDOM
| | | | | | | | | |
Collapse
|
|
37
|
Abstract
It is generally accepted that carbohydrate (CHO) feeding during exercise can improve endurance capacity (time to exhaustion) and exercise performance during prolonged exercise (>2 h). More recently, studies have also shown ergogenic effects of CHO feeding during shorter exercise of high intensity ( approximately 1 h at >75% of maximum oxygen consumption). During prolonged exercise the mechanism behind this performance improvement is likely to be related to maintenance of high rates of CHO oxidation and the prevention of hypoglycemia. Nevertheless, other mechanisms may play a role, depending on the type of exercise and the specific conditions. The mechanism for performance improvements during higher-intensity exercise is less clear, but there is some evidence that CHO can have central effects. In the past few years, studies have investigated ways to optimize CHO delivery and bioavailability. An analysis of all studies available shows that a single CHO ingested during exercise will be oxidized at rates up to about 1 g/min, even when large amounts of CHO are ingested. Combinations of CHO that use different intestinal transporters for absorption (e.g., glucose and fructose) have been shown to result in higher oxidation rates, and this seems to be a way to increase exogenous CHO oxidation rates by 20% to 50%. The search will continue for ways to further improve CHO delivery and to improve the oxidation efficiency resulting in less accumulation of CHO in the gastrointestinal tract and potentially decreasing gastrointestinal problems during prolonged exercise.
Collapse
Affiliation(s)
- Asker E Jeukendrup
- Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
| |
Collapse
|
|
38
|
|
|
39
|
Jentjens RLPG, Moseley L, Waring RH, Harding LK, Jeukendrup AE. Oxidation of combined ingestion of glucose and fructose during exercise. J Appl Physiol (1985) 2003; 96:1277-84. [PMID: 14657042 DOI: 10.1152/japplphysiol.00974.2003] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The purpose of the present study was to examine whether combined ingestion of a large amount of fructose and glucose during cycling exercise would lead to exogenous carbohydrate oxidation rates >1 g/min. Eight trained cyclists (maximal O(2) consumption: 62 +/- 3 ml x kg(-1) x min(-1)) performed four exercise trials in random order. Each trial consisted of 120 min of cycling at 50% maximum power output (63 +/- 2% maximal O(2) consumption), while subjects received a solution providing either 1.2 g/min of glucose (Med-Glu), 1.8 g/min of glucose (High-Glu), 0.6 g/min of fructose + 1.2 g/min of glucose (Fruc+Glu), or water. The ingested fructose was labeled with [U-(13)C]fructose, and the ingested glucose was labeled with [U-(14)C]glucose. Peak exogenous carbohydrate oxidation rates were approximately 55% higher (P < 0.001) in Fruc+Glu (1.26 +/- 0.07 g/min) compared with Med-Glu and High-Glu (0.80 +/- 0.04 and 0.83 +/- 0.05 g/min, respectively). Furthermore, the average exogenous carbohydrate oxidation rates over the 60- to 120-min exercise period were higher (P < 0.001) in Fruc+Glu compared with Med-Glu and High-Glu (1.16 +/- 0.06, 0.75 +/- 0.04, and 0.75 +/- 0.04 g/min, respectively). There was a trend toward a lower endogenous carbohydrate oxidation in Fruc+Glu compared with the other two carbohydrate trials, but this failed to reach statistical significance (P = 0.075). The present results demonstrate that, when fructose and glucose are ingested simultaneously at high rates during cycling exercise, exogenous carbohydrate oxidation rates can reach peak values of approximately 1.3 g/min.
Collapse
Affiliation(s)
- Roy L P G Jentjens
- Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
| | | | | | | | | |
Collapse
|
|
40
|
Abstract
The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen. The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to ~50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high (> or =1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins may be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.
Collapse
Affiliation(s)
- Roy Jentjens
- Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | | |
Collapse
|
|
41
|
Angus DJ, Febbraio MA, Hargreaves M. Plasma glucose kinetics during prolonged exercise in trained humans when fed carbohydrate. Am J Physiol Endocrinol Metab 2002; 283:E573-7. [PMID: 12169451 DOI: 10.1152/ajpendo.00443.2001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nine endurance-trained men exercised on a cycle ergometer at approximately 68% peak O2 uptake to the point of volitional fatigue [232 +/- 14 (SE) min] while ingesting an 8% carbohydrate solution to determine how high glucose disposal could increase under physiological conditions. Plasma glucose kinetics were measured using a primed, continuous infusion of [6,6-2H]glucose and the appearance of ingested glucose, assessed from [3-3H]glucose that had been added to the carbohydrate drink. Plasma glucose was increased (P < 0.05) after 30 min of exercise but thereafter remained at the preexercise level. Glucose appearance rate (R(a)) increased throughout exercise, reaching its peak value of 118 +/- 7 micromol. kg(-1). min(-1) at fatigue, whereas gut R(a) increased continuously during exercise, peaking at 105 +/- 10 micromol. kg(-1). min(-1) at the point of fatigue. In contrast, liver glucose output never rose above resting levels at any time during exercise. Glucose disposal (R(d)) increased throughout exercise, reaching a peak value of 118 +/- 7 micromol. kg(-1). min(-1) at fatigue. If we assume 95% oxidation of glucose R(d), estimated exogenous glucose oxidation at fatigue was 1.36 +/- 0.08 g/min. The results of this study demonstrate that glucose uptake increases continuously during prolonged, strenuous exercise when carbohydrate is ingested and does not appear to limit exercise performance.
Collapse
Affiliation(s)
- Damien J Angus
- Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia
| | | | | |
Collapse
|
|
42
|
Jeukendrup AE, Jentjens R. Oxidation of carbohydrate feedings during prolonged exercise: current thoughts, guidelines and directions for future research. Sports Med 2000; 29:407-24. [PMID: 10870867 DOI: 10.2165/00007256-200029060-00004] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Although it is known that carbohydrate (CHO) feedings during exercise improve endurance performance, the effects of different feeding strategies are less clear. Studies using (stable) isotope methodology have shown that not all carbohydrates are oxidised at similar rates and hence they may not be equally effective. Glucose, sucrose, maltose, maltodextrins and amylopectin are oxidised at high rates. Fructose, galactose and amylose have been shown to be oxidised at 25 to 50% lower rates. Combinations of multiple transportable CHO may increase the total CHO absorption and total exogenous CHO oxidation. Increasing the CHO intake up to 1.0 to 1.5 g/min will increase the oxidation up to about 1.0 to 1.1 g/min. However, a further increase of the intake will not further increase the oxidation rates. Training status does not affect exogenous CHO oxidation. The effects of fasting and muscle glycogen depletion are less clear. The most remarkable conclusion is probably that exogenous CHO oxidation rates do not exceed 1.0 to 1.1 g/min. There is convincing evidence that this limitation is not at the muscular level but most likely located in the intestine or the liver. Intestinal perfusion studies seem to suggest that the capacity to absorb glucose is only slightly in excess of the observed entrance of glucose into the blood and the rate of absorption may thus be a factor contributing to the limitation. However, the liver may play an additional important role, in that it provides glucose to the bloodstream at a rate of about 1 g/min by balancing the glucose from the gut and from glycogenolysis/gluconeogenesis. It is possible that when large amounts of glucose are ingested absorption is a limiting factor, and the liver will retain some glucose and thus act as a second limiting factor to exogenous CHO oxidation.
Collapse
Affiliation(s)
- A E Jeukendrup
- Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, England.
| | | |
Collapse
|
|
43
|
Gisolfi CV. Is the GI System Built For Exercise? NEWS IN PHYSIOLOGICAL SCIENCES : AN INTERNATIONAL JOURNAL OF PHYSIOLOGY PRODUCED JOINTLY BY THE INTERNATIONAL UNION OF PHYSIOLOGICAL SCIENCES AND THE AMERICAN PHYSIOLOGICAL SOCIETY 2000; 15:114-119. [PMID: 11390892 DOI: 10.1152/physiologyonline.2000.15.3.114] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gut usually meets the fluid, electrolyte, and nutrient requirements of mild to heavy exercise. Gastric emptying and intestinal absorption rates of beverages ingested during exercise equal sweat rates. However, strenuous or prolonged exercise under dehydrated conditions can produce gastrointestinal distress and tissue damage.
Collapse
Affiliation(s)
- Carl V. Gisolfi
- Department of Exercise Science at the University of Iowa, Iowa City, IA 52242-1111
| |
Collapse
|
|
44
|
Schott HC, Hinchcliff KW. Treatments affecting fluid and electrolyte status during exercise. Vet Clin North Am Equine Pract 1998; 14:175-204. [PMID: 9561695 DOI: 10.1016/s0749-0739(17)30219-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A number of feeding and management practices, dietary electrolyte supplements, and medications may affect fluid and electrolyte status in resting and exercising horses. The contents of the gastrointestinal tract of the equine athlete, unlike its human counterpart, are responsible for more than 10% of body weight. Although ingesta traditionally has been considered dead weight for the sprinting horse, it is a valuable reservoir of fluid and electrolytes that may be used during endurance exercise. Numerous strategies for hyperhydration of the equine athlete and for replacement of fluid and electrolytes lost via sweating were developed in preparation for competing in the hot and humid climate of the 1996 Olympic Games in Atlanta. These strategies have implications for all equine athletes. Medications, including sodium bicarbonate, furosemide, and acetazolamide commonly are used to enhance performance by either buffering alterations in fluid and electrolyte homeostasis or by ameliorating the effects of other conditions that may limit performance.
Collapse
Affiliation(s)
- H C Schott
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, USA
| | | |
Collapse
|
|
45
|
Abstract
Most studies relating to fluid replacement have addressed the problem of drinking during prolonged exercise. Fluid replacement is also very important for intermittent exercise, although it has not been extensively studied. More studies in this area would help coaches and athletes understand the importance of fluid balance and carbohydrate supplementation during intermittent exercise. Based on available data, it can be concluded that: (i) because of high exercise intensity, sweat loss and glycogen depletion during intermittent exercise are at least comparable with those during continuous exercise for a similar period of time. Therefore, the need to ingest a sport drink or replacement beverage during intermittent exercise may be greater than that during continuous exercise in order to maintain a high level of performance and to help prevent the possibility of thermal injury when such activity occurs in a warm environment; (ii) the volume of ingested fluid is critical for both rapid gastric emptying and complete rehydration; and (iii) osmolality (250 to 370 mOsm/kg), carbohydrate concentration (5 to 7%), and carbohydrate type (multiple transportable carbohydrates) should be considered when choosing an effective beverage for rehydration and carbohydrate supplementation during intermittent exercise.
Collapse
Affiliation(s)
- X Shi
- Gatorade Sports Science Institute, Gatorade Company, Barrington, Illinois, USA
| | | |
Collapse
|