Blueberry Bioactives Improve Endothelial Function in Adults with Metabolic Syndrome

There is a paucity of data suggesting that increased blueberry consumption improves cardiovascular risk factors in human subjects. This study investigated the role of blueberry bioactives on modifying vascular function and blood pressure in subjects at high risk for developing cardiovascular disease. A randomized, double blinded, and placebo‐controlled study was conducted in 44 adults with metabolic syndrome. They were randomized to receive twice daily blueberry bioactives (22.5g of freeze‐dried whole blueberry powder) added to a smoothie or an identical smoothie without the blueberry bioactives (i.e., placebo) per day for 6 weeks. Endothelial function (peripheral arterial tone) and blood pressure (7‐day automatic blood pressure monitoring device) were assessed pre‐ and post‐intervention. The subjects' mean change in blood pressure did not differ between the blueberry and placebo groups. However, the mean change in resting endothelial function, expressed as reactive hyperemia index, was improved significantly more in the blueberry versus placebo groups (P<0.05). Even after adjusting for confounding factors, i.e., percent body fat and gender, the blueberry group still had a greater improvement in endothelial function when compared to their counterpart. In conclusion, daily dietary supplementation of blueberry bioactives improved endothelial function over 6 weeks in subjects with metabolic syndrome.