Anthocyanins, pigments responsible for the jeweled red, purple and blue tones of plants, are shining in the research world. Anthocyanin-rich foods were part of folk medicine, botanists were fascinated by their role in pollination attraction and phytoprotection, and food scientists investigated anthocyanin color-quality issues in fruits and vegetables. Today, researchers are honing-in on the possible health benefits of anthocyanins, the most-abundant flavonoid in fruits and vegetables.
The promise of health benefits
“I think it’s a very exciting field of research,” says James Joseph, Ph.D., research physiologist, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston. “Anthocyanins are fairly good antioxidants and very good at scavenging free radicals. And they alter the compounds that come after free radicals, called stress signals. This protects against a variety of diseases.” Other mechanisms may also be at play, such as protection from DNA cleavage, estrogenic activity, enzyme inhibition, regulating immune response through increased cytokine production, anti-inflammatory action, lipid peroxidation and membrane strengthening.
Anthocyanins have been linked to a number of health benefits. Enhancement of night vision or overall vision was documented when anthocyanin pigments were delivered to animals and humans. Three anthocyanins from black currant stimulated regeneration of rhodopsin, a receptor in the retina. And the administration of anthocyanoside oligomer appeared to improve subjective symptoms and objective contrast sensitivity in myopia subjects with eye fatigue.
Cell culture and animal studies have indicated that berry anthocyanins are potent anticarcinogenic agents and protect against genomic instability at several sites in the carcinogenic pathway. Cancer-preventative mechanisms include modulation of carcinogen activation and detoxification, decreased DNA binding of the carcinogen, inhibition of oxiditative DNA damage, alteration in cell signaling and malignant transformation, and inhibition of cell invasiveness and metastasis.
The cardiovascular-disease protection from anthocyanins has a strong connection with oxidative-stress protection. Four anthocyanins from elderberries incorporated into endothelial cells demonstrated significant oxidative-stress protection. Anthocyanins also display a variety of positive effects on blood vessels, platelets and lipoproteins that may reduce the risk of coronary heart diseases.
Another area of research deals with the brain. They have been associated with modulation of cognitive and motor function, enhanced memory and prevention of age-related declines in neural function. Isolated, semipurified anthocyanins from purple sweet potato enhanced cognitive performance in mice and inhibited lipid peroxidation in rat brain tissues. Blueberry extracts appeared to reverse age-related deficits in memory and motor functions in rats.