In this study, a cross-over randomised controlled trial was carried out with three groups: one consuming fresh blueberries, one consuming freeze-dried blueberry powder, and one as the control group. All participated in 1 week of treatment, with a 1-week wash-out period between treatments. The study involved the measurement of systolic and diastolic blood pressure, pulse wave velocity, plasma cholesterol levels (low-density and high-density lipoprotein cholesterol and total cholesterol), triglyceride levels, and glucose and nitrite concentrations.

The results indicated an improvement of plasma nitrite levels following both whole blueberry and blueberry powder supplementations compared to their baselines, hinting at potential benefits to cardiovascular health. However, no other significant effects were observed for blood pressure, total cholesterol, low-density and high-density lipoprotein cholesterol, triglycerides, or glucose. Also, none of the changes in individual treatment arms were significantly different from the control. Essentially, the form of blueberry consumed, whether whole or in powder form, did not show any unique advantage in improving cardiovascular health factors.