Cooked Black Turtle Beans Ameliorate Insulin Resistance and Restore Gut Microbiota in C57BL/6J Mice on High-Fat Diets

Abstract

Colored common beans are associated with health promoting and chronic disease prevention effects. Male C57BL/6J mice were fed high-fat (HF) diets supplemented with cooked black turtle beans (HFB) to prevent obesity related insulin resistance. Mice on both HF and HFB were obese compared to mice fed a low-fat (LF) diet. Plasma low density lipoprotein (LDL) and triglyceride concentrations of mice fed HFB diet were 28% and 36.6% lower than those on HF diet. Homeostatic model assessment of insulin resistance (HOMA-IR) index of mice fed HFB diet was 87% lower than that of mice fed HF diet. Diabetes related biomarkers, gastric inhibitory polypeptide (GIP), leptin, glucagon, and inflammatory cytokines interleukin 4 (IL-4) and IL-5, 10 and 12, IFN-g and TNF-α were significantly affected by HFB diet. Pparα, Cyp7a1 and Fasn were down-regulated by HFB diet while LDL-R, Srebp-2, Adipoq and Slc2a4 were up-regulated by HFB diet. The ratio of Firmicutes/Bacteroidetes (F/B) was also decreased 64.1% by HFB diet compared to HF diet. The results indicated that cooked black turtle bean consumption could ameliorate insulin resistance and lower plasma LDL in mice fed HF diet through glucose signaling pathway and JNK/c-Jun pathway. Meanwhile, cooked black turtle bean consumption restored the gut microbiome.

Microwaving released more polyphenols from black quinoa grains with hypoglycemic effects compared with traditional cooking methods

“…However, Tan et al . exhibited that cooked black turtle bean consumption ameliorated insulin resistance and lowered plasma low‐density lipoprotein cholesterol (LDL‐C) in mice fed with high‐fat diet through glucose signaling pathway 37 . A controlled randomized interventional trial revealed that polyphenols‐rich diets (mainly consumed by tea, coffee and cooked vegetables) improved glucose metabolism in people with high cardiometabolic risk 38 .…”

“…36 However, Tan et al exhibited that cooked black turtle bean consumption ameliorated insulin resistance and lowered plasma low-density lipoprotein cholesterol (LDL-C) in mice fed with highfat diet through glucose signaling pathway. 37 A controlled randomized interventional trial revealed that polyphenols-rich diets (mainly consumed by tea, coffee and cooked vegetables) improved glucose metabolism in people with high cardiometabolic risk. 38 Collectively, cooking methods affect the content of starch, phenolic profile, and other nutrients of foods, which further affect the inhibition in digestive enzymes and starch digestion, and thus determine the postprandial glucose level comprehensively.…”

Dietary pulses as a means to improve the gut microbiome, inflammation, and appetite control in obesity

“…[40][41][42] These results are in comparison to purified HFD controls. Common beans have frequently elicited a reduction in the F/B ratio, 41,42,44 although no significant change in this ratio has also been reported. 40 Interestingly, Tan et al (2021) 44 reported a ratio that was 64.1% lower in bean-fed male C57BL/6J mice compared to a control group, despite no significant change in abundance of Firmicutes.…”

“…Common beans have frequently elicited a reduction in the F/B ratio, 41,42,44 although no significant change in this ratio has also been reported. 40 Interestingly, Tan et al (2021) 44 reported a ratio that was 64.1% lower in bean-fed male C57BL/6J mice compared to a control group, despite no significant change in abundance of Firmicutes. Actinobacteria abundance has been reported as both decreased 40 and unchanged 42 in response to bean supplementation.…”

“…consumption. 40,[42][43][44] In one study, navy bean supplementation for 12 weeks increased Prevotella abundance by 332-fold in 4-week-old male C57BL/6 mice compared to a control group. 40 It is also important to consider the ability of common beans to modulate the gut microbiota after obesity has been established in mouse models because the existence of microbial dysbiosis prior to bean consumption is more representative of human interventions.…”