A six-month study involving 138 overweight and obese older adults (50-75) with Metabolic Syndrome found that eating one cup of blueberries per day resulted in sustained improvements in vascular function and arterial stiffness, reducing the risk of cardiovascular disease by 12-15%. There was no benefit of a smaller 75 gram (half cup) daily intake of blueberries.
(2019). Blueberries improve biomarkers of cardiometabolic function in participants with metabolic syndrome—results from a 6-month, double-blind, randomized controlled trial.
The American Journal of Clinical Nutrition. 109(6), 1535 - 1545.