Effect of Whole Wheat and its Fractions on Adiposity, Insulin Resistance, and Fatty Liver

Abstract

Whole grains intake has been shown to decrease insulin resistance. Whether whole wheat decreases insulin resistance and, if so, which fraction of wheat is responsible, is unknown. Therefore we examined the effects of whole wheat and wheat fractions on adiposity, insulin resistance, and fatty liver, using Zucker Diabetic Fatty rats as model of obesity with diabetes. Rats were fed diets containing either 65% whole wheat flour, 54% refined wheat flour, 9.4% bran, 1.6% germ or 15% germ for 5 weeks. No differences in weight gain were observed between the obese control and the obese wheat-fed groups. Adiposity, determined by DEXA scanning and fat pad weights, did not differ statistically between the obese control and any obese wheat groups. Insulin resistance, measured by glucose tolerance and insulin tolerance tests, showed that whole wheat and all wheat fractions, except bran (trend only), improved insulin resistance. Liver lipids were determined gravimetrically as a measure of fatty liver. Whole wheat and all wheat fractions decreased total liver lipids, whereas bran and germ also reduced liver cholesterol. The reduction in insulin resistance and fatty liver suggests that consumption of whole wheat or its fractions may reduce the risk of developing type 2 diabetes. Supported by General Mills, Inc.