Among fruits, blueberries have one of the highest antioxidant capacities. Like cranberries, blueberries promote urinary tract health. They have also been shown to support memory, balance, and coordination. Blueberries also support eye health by increasing circulation of the capillaries of the eyes, which reduces oxidation in these tissues. They also strengthen other capillaries, as well as arteries and veins. And, blueberries have anti-inflammatory properties.
In a recent study, blueberries were given to athletes to measure their health benefits. Because strenuous exercise acutely generates oxidative stress as well as an inflammatory state, it serves as a great way to test antioxidant and anti-inflammatory capabilities. Subjects were given 250 g of blueberries per day for 6 weeks and 375 g 1 hour prior to 2.5 hour of running.
Twenty-five well-trained subjects were randomized into blueberry or control groups. Blood, muscle, and urine samples were obtained pre-exercise and immediately post-exercise, and blood and urine 1 hour post-exercise. Blood was examined for oxidative stress, cortisol, cytokines, homocysteine, leukocytes, T-cell function, natural killer (NK), and lymphocyte cell counts for inflammation and immune system activation, and antioxidant capacity. In addition, muscle biopsies were examined to evaluate stress and inflammation. Urine was tested for markers of nucleic acid oxidation. The results showed that increases in oxidative stress were significantly less in the blueberry group and immune counts were significantly greater in the blueberry group as compared to the control. This study indicates that daily blueberry consumption for 6 weeks increases NK cell counts, and acute ingestion reduces oxidative stress and increases anti-inflammatory cytokines.
Study: McAnulty LS, Nieman DC, Dumke CL, Shooter LA, Henson DA, Utter AC, Milne G, McAnulty SR. Effect of blueberry ingestion on natural killer cell counts, oxidative stress, and inflammation prior to and after 2.5 h of running. Appl Physiol Nutr Metab. 2011 Dec;36(6):976-84. Epub 2011 Nov 23.