American Journal of Clinical Nutrition, 2019 · Randomized controlled trial
One cup of blueberries a day for six months improved blood-vessel function and arterial stiffness in adults with metabolic syndrome, and raised HDL cholesterol in those not taking statins. Insulin resistance, the main outcome, did not change, and half a cup a day had no effect.
Always read the original paper for context — effect sizes, study populations and funding sources matter.





