Blueberry‐Enriched Diets Reduce Metabolic Syndrome and Insulin Resistance in Rats

Abstract

Several studies suggest that anthocyanin intake could modify risk factors for metabolic syndrome. Blueberries are a rich, whole‐food source of anthocyanins. We tested the effect of a semi‐purified diet with added whole blueberry powder (2% w:w) or a carbohydrate‐matched control diet on factors of metabolic syndrome in the obesity‐prone Zucker Fatty rat, fed either a low fat (10% fat) diet or a high fat (45% fat) diet. After 90 days, both the low fat blueberry (LFB) and high fat blueberry (HFB) groups had reduced abdominal fat compared to controls, and the LFB group had reduced body weight and % fat mass. Both LFB and HFB groups had significantly reduced triglycerides, total cholesterol, fasting insulin, and fasting glucose. LFB and HFB also had improved glucose clearance, as measured by a glucose tolerance test. Given the improved glucose control, we then measured mRNA transcripts in skeletal muscle and retroperitoneal fat related to glucose and lipid uptake and metabolism by PCR Array. The results suggest that regular intake of blueberry reduced several key risk factors for cardiovascular disease and metabolic syndrome. Furthermore, these benefits were augmented when fed a low fat diet. Finally, blueberry diet conferred tissue changes in several genes related to lipid and glucose metabolism, which could support the in vivo results of greater insulin sensitivity and reduced fat accumulation.