Nutritional benefits of blueberries

If one were to advertise a medicine that could retard aging, enhance brain function, improve eyesight, lower cholesterol and blood-lipid levels, and even induce apoptosis in cancer cells, it would sound like Hadacol or snake-oil. The common blueberry contains compounds – resveratrol, pterostilbene, piceatannol, and anthocyanins (1) – which are indicated by recent research to do just that.

Native to eastern North America, the blueberry (Vaccinium Sect. Cyanococcus) is now also cultivated in Australia and New Zealand. The Native Americans were the first to eat it, fresh or dried, no doubt as much out of necessity as because they are delicious. It is one of the few culinary fruits native to its range, and a one-cup serving contains 6% of the US RDA of vitamin C (2). In a part of the world where pine-needle tea was drunk to ward off scurvy, blueberries were health-food even in pre-Columbian times.

Supplementation of rat diets with blueberry extract was shown to reverse age-related neurological decline (3). The mechanism for this is still unknown, and there’s a chance that what applies to rats doesn’t apply to humans, but there’s reason to believe that blueberries have medicinal potential.

Modern science is still elucidating the effects of trace nutrients, concentrated largely in the blueberry’s peel, on human health. Much has been made lately of eating a “colorful diet”; the delphinidin anthocyanin pigments which protect the berry itself from ultraviolet radiation and oxidative stress have been shown to be potent antioxidants, absorbing oxygen radicals that would cause aging or carcinogenesis by damaging cellular proteins, lipids, and DNA (4).

Resveratrol, hypothesized to be a cause of the “French Paradox” that has European red-wine drinkers living long, healthy lives despite diets high in saturated fat, is also found in blueberries, at roughly ten percent of the level of grapes. Resveratrol has been shown to greatly increase both manganese superoxide dismutase (MnSOD) expression and activity levels, thus stimulating a natural antioxidant function in cells (5). in vitro studies have shown that resveratrol may also interfere with carcinogenesis and induce apoptosis (programmed cell death) in certain cancers.

While blueberries may not have as much resveratrol as grapes or peanuts, they contain high levels of the related compounds pterostilbene and piceatannol. Piceatannol has been shown to block the activity of a tyrosine kinase necessary