The antioxidant phytonutrients in blueberries are called anthocyanidins. Anthocyanidins have the ability to neutralize free radical damage to the collagen matrix of cells and tissues that can lead to cataracts, glaucoma, varicose veins, hemorrhoids, peptic ulcers, heart disease and cancer. They also directly cross-link with collagen fibers to form a more stable collagen matrix.

The cholesterol fighting effect of cholesterol is due to the actions of the phytosterol, pterostilbene. Pterostilbene binds to the PPAR-alpha (peroxisome proliferator activated) receptor. This receptor is important in reducing the number of cholesterol and other types of lipids in the bloodstream.

According to a study conducted at the University of Guelph in Ontario, the mechanism by which blueberries help protect the brain and central nervous system is by causing an increase in serum antioxidant status, which is linked to reduced risk of chronic and degenerative diseases (Kay CD et al. The effect of wild blueberry (Vaccinium angustifolium) consumption on postprandial serum antioxidant status in human subjects. Br J Nutr. 88, 4:389-98, 2002).

Blueberries appear to promote neurogenesis (the growth of neurons). This is apparently due to the anthocyanin dyes which give blueberry their color. These dyes are able to cross the blood-brain barrier and trigger nuerogenesis.

Blueberries have the effect of relaxing blood vessels, preventing increased blood pressure and all of the problems that go with that condition.

What accounts for the amazing cognitive benefits of the blueberry? “What blueberries do is what simply can be called strengthening the brain by taking advantages of the brain's tremendous redundancy," says James Joseph, lead researcher at the U.S. Department of Agriculture Human Nutrition and Research Center on Aging at Tufts University.. "Blueberries have compounds that boost neuron signals and help turn back on systems in the brain that can lead to using other proteins to help with memory or other cognitive skills."

Blueberries also keep cell membranes healthy, allowing for more efficient transportation of nutrients around the body.