Resveratrol in Grapes & Grape Juice
Resveratrol, well known for its powerful longevity and health benefits, is popularly known to be found in red wine. It is - red grapes (or, rather, their skins) are rich in resveratrol, and the process by which red wine is made allows alcohol to leach out the resveratrol in grape skins and must into the wine. (The lack of this long maceration step is why white wine is relatively low in resveratrol)
But how much resveratrol can you find in red grapes and in red grape juice? Is it comparable to what you find in red wine?
Before we even start addressing with numbers, it's important to understand that resveratrol can appear in different quantities in red grapes. Grapes that are grown in moist climates have more resveratrol than the same grapes grown in dry climates, because resveratrol is a phytoalexin that the plant uses to ward off fungal attack which is more common in more humid climates.
Also, another compound found in grape skins, piceid, is converted to resveratrol during the wine-making process, so red wine will tend to have more resveratrol than a comparable amount of red grape juice, in which a greater proportion of unconverted piceid will be found.
As for quantities? Be prepared to eat a lot of grapes, or drink a lot of grape juice, in order to get the same amount of resveratrol that you find in resveratrol supplements (which use Japanese knotweed, an herb, as the resveratrol source).
Red grape juice: 1.14-8.69 mg resveratrol per liter of juice*
Red grapes: 0.24-1.25 mg resveratrol per cup (160 g) of grapes*
Most supplement pills have 25 mg or more resveratrol per pill, so the equivalent of what you'll find in grapes or in their juice is relatively small. However, red grape juice will have about 5 to 20 times the resveratrol of a similar amount of white wine. Red wine, though, can have as much as 2-3 times the resveratrol of white wine, but still quite a bit less than your average resveratrol supplement.
* Romero-Perez AI, Ibern-Gomez M, Lamuela-Raventos RM, de La Torre-Boronat MC. Piceid, the major resveratrol derivative in grape juices. J Agric Food Chem. 1999;47(4):1533-1536.