Grape seeds have a high concentration of flavonoids and oligomeric proanthocyanidins, (OPC). These compounds also found in grape seed in lower concentrations in grape skin, and . Grape seed contains various lipids, including the omega-6 fatty acid linoleic acid and the omega-9 fatty acid oleic acid. Grape seed provides the essential amino acids leucine, phenylalanine and valine, and the non-essential amino acids arginine and cystine.
OPCs are found in wine as well as grape juice. OPC is why we have what is called the French Paradox in that people in France who drink a lot of red wine don’t tend to have a lot of heart problems. Even though they smoke and eat a lot of fatty foods. Of course you would have to drink quite a few bottles of wine or grape juice to get the amount of valuable OPC contained in a high quality OPC supplement.