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. Their study of 490,000 men and women in the United States indicated that drinkers reduce their risk of dying from cardiovascular disease by 30 to 40 percent. In contrast, people who drink large amounts of alcohol in a single binge appear to gain fewer advantages.