A polyphenol called anthocyanin is plentiful in black cherries. It is anthocyanin that gives black cherries their dark purple color. Anthocyanins are potent antioxidants and may help protect blood vessel walls from free radicals. They also may facilitate vasorelaxation, relaxation of the blood vessels, which can lower blood pressure.
Biological Research
A study in the April 2006 issue of the "Journal of Applied Physiology" reported on the effects of anthocyanin-rich chokeberry, bilberry and elderberry extracts on vasorelaxation in sections of pig coronary arteries. Chokeberry and bilberry but not elderberry extracts caused increasing relaxation as dosages were increased. At low doses, chokeberry extract protected against experimentally introduced free radicals, preventing vasoconstriction.
Human Studies
Studies in humans have indicated benefits to blood pressure from eating a diet rich in anthocyanin-containing fruits, but not from anthocyanin supplements. According to a large dietary intake study reported in the February 2011 "American Journal of Clinical Nutrition," during 14 years of followup, participants with the highest anthocyanin intake, which was mostly from blueberries and strawberries, had an 8 percent reduced risk of hypertension. However, a study of 35 men in the May 2011 "Journal of Human Hypertension" found that taking a 320 mg anthocyanin supplement twice daily for four weeks had no effect on blood pressure. It is possible that this study was too short to show an effect. Alternatively other nutrients in fruits may contribute to their blood pressure benefits. Antioxidants are thought to be more effective when there is a balanced variety as in fruits and vegetables.
Anthocyanins
Anthocyanins are present in a variety of red and purple fruits as well as vegetables, such as red cabbage and red lettuce. Generally the darker the color, the more anthocyanin there is. Black cherries are an especially rich source. Anthocyanin is only one of the many polyphenols with antioxidant activity. Eat a diet rich in colorful fruits and vegetables to maximize your antioxidant defenses.
Black Cherries
Black cherries are native to Eastern North America. They have a sharper taste than sweet cherries and can be used in pies or jams. Many black cherry juice products are available.
References
- "Journal of Applied Physiology"; Direct Vasoactive and Vasoprotective Properties of Anthocyanin-Rich Extracts; D.R. Bell, et al., April 2006
- "American Journal of Clinical Nutrition"; Habitual Intake of Flavonoid Subclasses and Incident Hypertension in Adults; A. Cassidy, et al., February 2011
- "Journal of Human Hypertension"; Effects of Anthocyanins on Blood Pressure and Stress Reactivity ... ; S.S. Hassellund, et al., May 2011
