Where is Resveratrol Found
The content of resveratrol in grapes is the highest in its skin, which has 50-100 micrograms per gram. This amount varies depending on the grape cultivar, the geographic origin, and exposure to fungal infection. Resveratrol is produced in the plant as a defense against disease and fungus. Since fungal infections are more common in cooler climates, grapes produced in cooler climates tend to have a higher concentration of resveratrol. In one serving of red grapes (approximately 160 g), the total amount of resveratrol is estimated at 0.24 to 1.25 mg.
When it comes to wine, the content of resveratrol is related to the length of time during the fermentation process that the grape skins are present. In the production of white wine the skins are removed earlier than in the making of red wine. The total amount of resveratrol per serving of wine (a 5-ounce glass) for white wines is found to be between 0.01 to 0.27 mg. For red wines, the content of resveratrol is between 0.29 to 1.89 mg per serving. In red grape juice, which is not a fermented drink, the content of resveratrol is between 0.17 to 1.03 mg per 5-ounce glass. Some reports have indicated that wines produced from muscadine grapes, both red and white, may contain more than 40 mg/L. However, other similar studies found little or no resveratrol in different varieties of muscadine grapes. A study by Stervbo, Vang, and Bonnesen in 2005 indicated that wines made from the grapes of the Pinot Noir and St. Laurent varieties showed the highest level of trans-resveratrol. However, no region can be said to produce wines with significantly higher levels of resveratrol than all other regions. Additionally, the levels of resveratrol in grapes and wines vary from region to region and from one year to another. It is worth noting that although red wine is a relatively rich source of resveratrol, other polyphenols which produce health benefits are present in red wine at higher concentrations than resveratrol.
Resveratrol is present in peanuts at the following levels: in a serving (146 g) of raw peanuts, 0.01 to 0.26 mg; per serving (180 g) of boiled peanuts, 0.32 to 1.28 mg; per serving (258 g) of peanut butter, 0.04 to 0.013 mg. In cocoa powder, baking chocolate, and dark chocolate, average content of resveratrol per serving ranges from 14.1 to 18.5 micrograms.
