Apparently, phenolics prevent fat-like substances in the bloodstream from oxidizing and clogging the arteries. At first, this leads to subtle damage, and then eventually to the formation of advanced plaque. The buildup of plaque can lead to clogging of the arteries, a major cause of heart attacks. Andrew Waterhouse explains why more research is needed to understand the potential health benefits of phenolics. It's well known that these substances are antioxidants in a chemical sense. .
More research still needs to be done, but certainly the initial research is encouraging.