Gut microbiota as a target for prevention and treatment of type 2 diabetes: Mechanisms and dietary natural products

Table 1 Main preclinical and human data reporting the effects of dietary natural products on gut microbiota and associated mechanisms in diabetes mellitus and related complications

Name	Model	Key findings	Ref.
Pumpkin polysaccharide	HFD (mice)	Increases SCFAs production; selectively enhances the abundance of Bilophila and Prevotella	Liu et al[118]
Inulin	T2DM in rats induced by HFD and streptozotocin and clinic trial	Increases SCFA-producing bacteria including Lachnospiraceae, Phascolarctobacterium, Bacteroides, and Akkermansia muciniphila	Li et al[112] and Food and Drug Administration, HHS[113]
Lessonia nigrescens ethanolic extract	T2DM mice (streptozotocin injection)	Increases the ratio of Bacteroidetes/Firmicutes in the intestine	El Kaoutari et al[115]
Grape pomace extract	HFD (mice)	Reduces the abundance of Desulfovibrio and Lactococcus, and increases the abundance of Allobaculum and Roseburia; improves the gut barrier function	Bowey et al[123]
Resveratrol	NASH rat model	Ameliorates the intestinal barrier dysfunction and inflammation	Li et al[124]
Quercetin	HFD (mice)	Reverts gut microbiota imbalance and related endotoxemia-mediated TLR4 pathway induction	Solon-Biet et al[61]
Berberine	db/db mice High fat diet (mice and rats) FXR knockout (FXRint-/-) mice	Modulates the ratio of Firmicutes/Bacteroidetes; increases SCFA content in feces; regulates BCAAs biosynthesis and catabolism in liver and adipose tissue; reduces the increased expressions of inflammatory mediators and alleviates gut permeability by decreasing LPS level in plasma; modulates the bile acid cycle and subsequently the ileal FXR signaling pathway	Tesar and Kottke[129], He et al[130], Song et al[131], Wang et al[132], and Zhang et al[133]
Capsaicin	ob/ob mice	Increases the ratio of Firmicutes to Bacteroidetes and the number of Roseburia; decreases the levels of proinflammatory cytokines, including TNF-α and IL-6	Christodoulou et al[128]

HFD: High-fat diet; SCFAs: Short-chain fatty acids; T2DM: Type 2 diabetes mellitus; NASH: Nonalcoholic steatohepatitis; BCAAs: Branched-chain amino acids; FXR: Farnesoid X receptor; LPS: Lipopolysaccharide; TNF-α: Tumor necrosis factor-α; IL-6: Interleukin 6.