Research studies on the heart-health benefits of red wine have reported mixed results. Some studies show that red wine seems to have even more heart-health benefits than other types of alcohol, while other studies show that red wine isn't any better than beer, white wine or liquor for heart health. There's still no clear evidence yet that red wine is superior to other forms of alcohol when it comes to possible heart-health benefits. If you drink alcohol, do so in moderation. This means an average of one to two drinks per day for men and one drink per day for women. (A drink is one 12 oz. beer, 4 oz. of wine, 1.5 oz. of 80-proof spirits, or 1 oz. of 100-proof spirits.)

The studies supporting red wine suggest that the antioxidants in red wine called polyphenols help protect the lining of blood vessels in your heart. Antioxidants are substances or nutrients in our foods which can prevent or slow the oxidative damage to our body. When our body’s cells use oxygen, they naturally produce “free radicals” which can cause damage. Antioxidants act as "free radical scavengers" and hence prevent and repair damage done by these free radicals. You may have read about the antioxidant called Resveratrol, found in the skin of red grapes. Heart disease, macular degeneration, diabetes and cancer are all contributed to by oxidative damage.

Additional Resources:

http://www.americanheart.org/presenter.jhtml?identifier=4422