Macular degeneration is the leading cause of blindness in adults over age 65. Once the condition is diagnosed, there is no cure, notes Toni P. Miles of the University of Texas Health Science Center at San Antonio. If further research confirms that moderate alcohol consumption can stave off the disorder, the findings would represent an important public health advance, Miles says. This epidemiological study cannot explain how wine might shield the eye from macular degeneration. However, Obisesan says one hypothesis is that free radicals, highly injurious oxygen molecules, may damage the macula, the part of the eye responsible for central vision.
Wine contains a substance called resveratrol that helps disarm free radicals.
Another hypothesis holds that alcohol may ward off macular degeneration through its beneficial effect on the cardiovascular system. Some researchers believe macular degeneration is related to heart and vessel disease. Heart attacks occur when a blood clot lodges in a coronary artery already choked with atherosclerotic plaque. When blood flow to the heart is reduced or shut off, a heart attack can result. Doll notes that alcohol boosts concentrations of HDL, the good cholesterol, and discourages the formation of blood clots.