Resveratrol is a polyphenol antioxidant found in high concentrations in grapes and certain other plants, including peanuts and cocoa. Plants produce resveratrol to ward off pathogens and manage environmental stress, such as excess sunlight or injury. Red grape resveratrol content spans a wide range and depends on the type of grape, growing conditions and location.
Spanish
Spanish red grapes contain among the highest levels of resveratrol, according to the Linus Pauling Institute. They provide up to 12.59 mg per liter in Spanish red wine, compared to a maximum of 7.13 mg per liter among red wines, globally. Spanish red grape juice contains between 1.14 and 8.69 mg per liter.
New York State
New York-grown red grapes contain more of the heart-healthy antioxidant than red grapes from other parts of the world. In a comparison, New York red wines tested higher than some from California, other states and other parts of the world. Measured in units called micromolar, 11 out of 17 New York pinot noir wines contained over 10 micromolar concentration of resveratrol and averaged 13.6 micromolar. An average red wine might have a resveratrol content of 3 or 4 and anything above 5 is considered high. Average resveratrol content of all New York wines tested was 7.5, greater than the 5.8 average for all non-New York red wines and 5.0 for California red wines.
Muscadine
Muscadine grapes, a variety of large non-cluster-forming grapes native to the southern United States, provide particularly high resveratrol levels, with the darker varieties containing as much as 25 mg per kg, according to the United States Department of Agriculture. Muscadine grapes are also high in overall phenolic antioxidant content, a result of their unique adaptation to the hot humid climate in which they grow.
Merlot
Brazilian merlot wines contain up to 15 mg per liter of a certain type of resveratrol, known as cis-resveratrol, according to a study published in the July 2005 issue of the "Journal of Agricultural and Food Chemistry." The study evaluated 12 commercial wines from the southern part of Brazil.
White Grapes
Don't discount the health value of white grapes in your search for high-antioxidant grapes. White grape skins, where much of the resveratrol content in a grape is stored, are removed before processing into juice and wine, says Dr. Ray Sahelian. This results in false low values. The antioxidant value of white grapes, when the whole fruit is taken into account, may be on par with that of red grapes.
References
- Linus Pauling Institute; Resveratrol; Jane Higdon, Ph.D.; March 2005
- "Cornell Chronicle"; Higher Levels of Resveratrol Found Among N.Y. Red Wines; Blaine P. Friedlander Jr.February, 1998
- "Acta Horticulturae"; Nutraceutical Compound Concentrations of Muscadine (Vitis rotundifolia Michx.) Grape Cultivars and Breeding Lines; S.J. Stringer, et al; 2009
- RaySahelian.com:Grape Health Benefit Information, Juice Content of Resveratrol and Nutritional Composition
- "Journal of Agricultural and Food Chemistry"; Determination of Stilbenes (Delta-viniferin, Trans-astringin, Trans-piceid, Cis- and Trans-resveratrol, Epsilon-viniferin) in Brazilian Wines; X. Vitrac, et al; July 2005
- University of Maryland Medical Center: Resveratrol
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