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

Yuqing Tan,Christina C Tam,Yan Zhang,Shi Meng,Priscila Alves,Wallace Yokoyama

doi:10.3390/foods10081691

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.

Highlights

Legumes and their products play an important role in traditional diets in many regions such as Europe, Mediterranean, Asia, South America and North America [1]
HFB diet significantly induced the enrichment of Lachnospiraceae and Muribaculaceae compared to high fat (HF) and LF
The present study demonstrated that cooked black turtle bean supplementation in a HF diet had health promoting effects in terms of lipid and glucose metabolism

Summary

Introduction

Legumes and their products play an important role in traditional diets in many regions such as Europe, Mediterranean, Asia, South America and North America [1]. Varieties of Phaseolus vulgaris (navy bean, pinto bean, kidney bean and black turtle bean) are the major beans consumed in US [2] Their importance as a protein source is exemplified by the US Department of Agriculture’s Food Guide Pyramid that lists legumes in the same high protein group as meat, poultry, fish and egg [3]. In recent years, colored common beans such as black turtle bean, black soybean, lentil, kidney bean and pinto bean have attracted more consumer interest because their darker colors are associated with health promoting and anti-chronic disease properties [4,5] Among these commonly consumed beans, black turtle bean possesses the highest phenolic content (6.89 mg GAE/g) and antioxidant activities (79.27 μmol TE/g) [6]. Tan et al [7] reported extremely high phenolic content (599.22 mg GAE/g) and antioxidant capacity (35,830 μmol TE/g) of purified and fractionated phenolic extracts from black soybean and black turtle bean, and found that some phenolic fractions possessed inhibitory activities against lipase, α-glucosidase and α-amylase, which were even higher than commercial drugs used for diabetes treatment [8]

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