Ultra-processed food, obesity, and colon cancer: A systematic review and meta-analysis

Table 1 Study descriptor table

Ref.	Study design	No. of participants	Study region	Age range	Outcome	Major findings
Wang et al[12], 2022	Three prospective cohorts	Men (n = 46341), women (n = 159907)	United States	30-55, 25-42, 40-75	Compared with those in the lowest fifth of ultra-processed food consumption, men in the highest fifth of consumption had a 29% higher risk of developing colorectal cancer	High consumption of whole ultra-processed foods in men and specific subgroups of ultra-processed foods in men and women was associated with an increased risk of colorectal cancer
Oxentenko et al[13], 2010	Prospective study	36941 women	Mayo Clinic Rochester and the University of Minnesota, United States	55-69	Baseline height, weight, BMI, hip circumference, waist circumference, and WHR were all positively associated with incident colorectal cancer	A strong association between body size and colorectal cancer risk among older women
Romaguera et al[14], 2021	Case-control	1852	Spain	20-85	Consumption of ultra-processed foods and drinks was associated with a higher risk of colorectal cancer (OR for a 10% increase in consumption	Results suggest an association between the consumption of ultra-processed foods and drinks, and colorectal cancer
Terry et al[15], 2002	Prospective cohort study	89835 women	Canada	40-59	Obesity was associated with an increased risk of colorectal cancer among premenopausal women at baseline. There was no association among postmenopausal women	Obesity is associated with an increased risk of colorectal cancer in premenopausal women but is not associated with altered risk in postmenopausal women
Movahedi et al[16], 2015	Prospective study	937	Unspecified	Median 44.9	During follow-up, 55 of 937 participants developed CRC. For obese participants, CRC risk was 2.41 × (95%CI: 1.22-4.85) more significant than underweight and normal-weight participants	Obesity is associated with substantially increased CRC risk in patients with LS, but this risk is abrogated in those taking aspirin
Kitahara et al[17], 2013	Prospective study	966	United States	55-74	Compared with normal-weight men (18.5-24.9 kg/m2), obese men (≥ 30 kg/m2) had a significantly higher risk of incident adenoma (OR, 1.32; 95%CI: 1.06-1.65) and colorectal cancer	Obesity is critical throughout the natural history of colorectal cancer, at least in men. Colorectal cancer prevention efforts should encourage achieving and maintaining a healthy body weight in addition to regular screenings
Anderson et al[18], 2014	Multicentre, parallel-group, randomized controlled trial	329	Scotland	50-74	Differences between groups were significant for waist circumference, body mass index, blood pressure, blood glucose level, diet, and physical activity. No reported adverse events were related to trial participation	Significant weight loss can be achieved by a diet and physical activity intervention offering considerable potential for risk reduction of disease in older adults
Flaherty et al[19], 2018	Prospective study	70	United States	Mean 66.1	Patients with mismatch repair-deficient tumors (n = 11) had a lower mean BMI than those with mismatch repair-proficient tumors (n = 59) (22.16 vs 26.30 kg/m2, respectively; P = 0.029)	Tumor mismatch repair status and obesity are correlated in patients with colon cancer; increased
Hall et al[20], 2019	RCT	20	Unspecified	Mean 31.2	Weight changes were highly correlated with energy intake (r = 0.8, P < 0.0001), with participants gaining 0.9 ± 0.3 kg (P = 0.009) during the ultra-processed diet and losing 0.9 ± 0.3 kg (P = 0.007) during the unprocessed diet	Limiting the consumption of ultra-processed foods may be an effective strategy for obesity prevention and treatment
Canella et al[21], 2014	Cross-sectional study	55970	Brazil	Unspecified	Compared with those in the lower quartile, people in the upper quartile of household consumption of ultra-processed products were 37% more likely to be obese	Greater household availability of ultra-processed food products in Brazil is positively and independently associated with a higher prevalence of excess weight and obesity
Silva et al[22], 2018	Cross-sectional study	45	Brazil	35-64	Individuals in the fourth quartile of percentage energy contribution from ultra-processed foods presented a higher BMI and WC and higher chances of being overweight or obese and having significantly increased WC compared with those in the first quartile	Results indicate the existence of associations between more significant energy contributions from ultra-processed foods and higher BMI and WC, which are independent of total energy intake
Louzada et al[23], 2015	Cross-sectional study	30243	Brazil	≥ 10	Ultra-processed foods represented 30% of the total energy intake. Those in the highest quintile of consumption of ultra-processed foods had significantly higher body-mass-index and higher odds of being obese and excess weight compared with those in the lowest quintile of consumption	Findings support the role of ultra-processed foods in the obesity epidemic in Brazil
Nardocci et al[24], 2019	Cross-sectional study	19363	Canada	18 or more	Individuals in the highest quintile of ultra-processed food consumption were 32% more likely to have obesity than those in the first quintile	Ultra-processed food consumption is positively associated with obesity
Juul et al[25], 2018	Cross-sectional study	15977	United States	20–64	Individuals in the highest quintile of ultra-processed food consumption were 32% more likely to have obesity than those in the first quintile	Findings support that higher consumption of ultra-processed food is associated with excess weight and that the association is more pronounced among women
Rauber et al[26], 2020	Cross-sectional study	6143	United Kingdom	19-96	The consumption of ultra-processed food was associated with increased BMI and obesity in both sexes	Higher consumption of ultra-processed food is associated with greater adiposity in the United Kingdom adult population. Policymakers should consider actions that promote the consumption of unprocessed or minimally processed foods and reduce the consumption of ultra-processed foods
Schnabel et al[7], 2019	Prospective cohort study	44551	France	45 or older	A 10% increase in the proportion of ultra-processed food consumption was statistically significantly associated with a 14% higher risk of all-cause mortality	An increase in ultra-processed food consumption is associated with higher mortality
Mendonça et al[5], 2016	Prospective cohort study	8451	Spain	Unspecified	A total of 1939 incident cases of overweight and obesity were identified during follow-up. After adjustment for potential confounders, participants in the highest quartile of ultra-processed food consumption were at a higher risk of developing overweight or obesity	Ultra-processed food consumption was associated with a higher risk of being overweight and obese

BMI: Body mass index; WHR: Waist-to-hip ratio; OR: Odds ratio; CRC: Colorectal cancer; LS: Lynch syndrome; RCT: Randomized clinical trial; WC: Waist circumference.

Table 2 Joanna Briggs Institute critical appraisal checklist for analytical cross-sectional studies

Ref.	Q1: Inclusion criteria	Q2: Subject setting	Q3: Valid exposure measurement	Q4: Standard outcome criteria	Q5: Confounding factors identified	Q6: Strategies for confounding	Q7: Valid outcome measurement	Q8: Statistical analysis
Wang et al[12], 2022	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Oxentenko et al[13], 2010	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Romaguera et al[14], 2021	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Terry et al[15], 2002	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Movahedi et al[16], 2015	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Kitahara et al[17], 2013	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Anderson et al[18], 2014	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Flaherty et al[19], 2018	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Hall et al[20], 2019	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Canella et al[21], 2014	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Silva et al[22], 2018	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Louzada et al[23], 2015	Yes	Yes	Yes	Yes	No	Not applicable	Yes	Yes
Nardocci et al[24], 2019	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Juul et al[25], 2018	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Rauber et al[26], 2020	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Schnabel et al[7], 2019	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Mendonça et al[5], 2016	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes