Wine contains protective polyphenols that reduce endothelin-1, a substance that clogs and stiffens arteries. Healthy arteries reduce the risk of stroke; studies have found that even very moderate drinking— — as little as a glass of wine a week— — lowered the risk of most common strokes by around 20 percent. Additionally, resveratrol, an antioxidant present in the skins of red grapes, helps prevent cancer cells from getting a key protein required for their growth. Drinking wine in moderation also helps ward off Helicobacter pylori, the bacteria that causes stomach ulcers.