Evaluation of Poorly-Bioavailable Cocoa Flavanols and Their Gut Microbial Metabolites in Potentiating Anti-diabetic Activities Through BTBR.Cg-Lepob/ob/WiscJ Mice

Abstract

Abstract Objectives Cocoa (Theobroma cacao) is a concentrated dietary source of flavanols that have beneficial activities against type-2 diabetes. These compounds have limited small intestinal absorption and are metabolized by the microbiota to bioavailable metabolites that may exert anti-diabetic effects locally and in peripheral tissues. Our objectives were to 1) determine the role of the gut microbiome in facilitating protective effects of cocoa flavanols, and 2) evaluate these effects in a novel mouse model of progressive type-2 diabetes. Methods A small pilot study (n = 3) of male and female BTBR mice (wild-type and homozygous for the Lepob mutation) received either control or cocoa extract-supplemented diet for 10 weeks. Half the animals were administered antibiotics orally to knock down the commensal gut microbiota. Glucose and insulin tolerance tests were conducted at weeks 1 and 5 and 2 and 6, respectively. Weight gain and food intake were monitored weekly. Biomarkers of gut integrity and inflammation were assessed by ELISA. Results Baseline fasting blood glucose (FBG) levels in five-week-old homozygous males and females were measured at 211–271 mg/dL and 112–234 mg/dL, respectively. After five weeks, FBG measured at 281–438 mg/dL and 177–562 mg/dL, respectively. Cocoa provided moderate, yet not significant, protection against weight gain in homozygous males when compared to homozygous males fed control diet. Cocoa provided no significant protection against hypoglycemia in homozygous male or female mice when compared to homozygous controls. In treatment comparisons with and without antibiotics, knocking out the commensal gut microbiota appeared to have minimal effect on weight gain and glycemic control in both males and females. Conclusions Cocoa did provide a moderate level of protection for homozygous males when directly comparing weight gain and FBG across sex. While the microbiome has displayed a promising role in the bioavailability of large flavanols, in this particular model, the impact was minimal. Overall, cocoa was ineffective against the mediation of advanced diabetes and further work must be conducted to understand if this conclusion is isolated to this model of progressive type-2 diabetes. Funding Sources This work was supported by the US Department of Agriculture by AFRI grant 2020–67,017-30,846.