The grape, one of the oldest cultivated fruits, was brought to America by Spanish explorers. A wealth of antioxidants, including resveratrol, quercetin, anthocyanins and catechins make grapes a powerfully healthy food. Grapes and grape products have been shown helpful at preventing and treating some forms of cancer, diabetes and cardiovascular disease. Research and expert opinions are divided about the merits of grapes for treating high blood pressure.
Ineffective
Grapes did not help lower blood pressure in a study conducted at the Evans Department of Medicine and the Whitaker Cardiovascular Institute of Boston University School of Medicine. In the double-blind study, 64 participants drank 7 mL per kg body weight per day of Concord grape juice for four weeks. Grape juice did not affect systolic pressure -- the upper number of the blood pressure ratio, or diastolic pressure -- the lower number. Also, no changes in stress-related blood pressure were observed in the study, published in the November 2010 issue of the "American Journal of Clinical Nutrition."
Measurable Improvement
A Korean study reported a measurable decrease in both systolic and diastolic blood pressure in a study of 40 men with high blood pressure. Participants consumed 5.5 mL per kg body weight of Concord grape juice for eight weeks. Systolic blood pressure was reduced by an average of 7.2 mm Hg and diastolic blood pressure was reduced by an average of 6.2 mm Hg. Grape juice was approximately twice as effective as a placebo. The study appeared in the 2004 issue of the journal "Biofactors."
Antioxidants
Antioxidants in grape juice may benefit patients with hypertension by defending against oxidation and preventing damage to white blood cells, according to a study published in the August 2009 issue of the "Annals of the New York Academy of Sciences." In the eight-week study 5.5 mL per kg body weight of grape juice consumption per day resulted in a 26 percent decrease in damage to white blood cells, implying lowered risk for atherosclerosis, which contributes to elevated blood pressure. The free-radical trapping ability of the blood also increased. Researchers concluded that grape juice may improve antioxidant defenses in people with high blood pressure.
Potassium
High potassium levels in grapes may contribute to lower blood pressure, according to Frances Sienkiewicz Sizer, author of "Nutrition: Concepts and Controversies." Wine also confers the benefits of potassium, however, the alcohol content of wine depletes potassium and other nutrient minerals, such as calcium, phosphorus, magnesium and zinc. Grape juice or alcohol-free wine are potentially better choices for lowering blood pressure. The antioxidant flavonoid compounds in grape juice and wine protect against atherosclerosis, a condition that leads to high blood pressure. Consult your doctor for advice on eating grapes to lower blood pressure.
References
- "American Journal of Clinical Nutrition"; Effects of Concord Grape Juice on Ambulatory Blood Pressure in Prehypertension and Stage 1 Hypertension; M. Dohadwala, et al.; November 2010
- "Biofactors"; Concord Grape Juice Supplementation Reduces Blood Pressure in Korean Hypertensive Men: Double-blind, Placebo Controlled Intervention Trial; Y. Park, et al.; 2004
- "Annals of the N.Y. Academy of Science"; Changes in Antioxidant Status, Blood Pressure, and Lymphocyte Dna Damage from Grape Juice Supplementation; Y.Park, et al.; August 2009
- Nutrition: Concepts and Controversies; Frances Sienkiewicz Sizer; 2010
- Nutrition and Health: Web Resource Guide for Consumers, Healthcare Providers ...; Eugene A. DeFelice; 2003
