By Sally Squires
Tuesday, April 22, 2008
Raising a glass of wine and wishing "Salud!" -- Health! -- is one of life's many pleasures.
But for women, this well-meaning cheer rings hollow: There's mounting evidence that drinking wine and other alcoholic beverages increases the risk of breast cancer.
That's not the image that many people have about sipping wine, beer or other alcoholic beverages in moderation. A recent Harvard study of 878 people found that nearly two-thirds of drinkers and about a third of teetotalers considered such imbibing to be safe and healthful. So healthful that about 30 percent of those surveyed said the purported health benefits of alcohol are one reason they drink.
The link between alcohol and breast cancer is something that "almost nobody in the study had heard about," says the survey's lead author, Kenneth Mukamal, an internist at Beth Israel Deaconess Hospital in Boston. Only 10 percent correctly identified breast cancer as a possible risk of moderate drinking, the researchers reported in the journal Family Medicine.
Since the survey ended, Mukamal continues to informally poll people at cocktail parties. "I've spoken with other colleagues and friends who I would have considered to be fairly sophisticated consumers," he says. "And most have no idea about this, either."
Yet just this month, Danish researchers added to a substantial base of evidence linking alcohol consumption to an increased risk of breast cancer in women. These results offer a cautionary note for younger women and underscore that it's never too early to go easy on alcohol. The researchers tracked nearly 10,000 women for 27 years. They found that the amount of alcohol the women consumed when the study began, rather than after menopause, correlated best with their breast cancer risk nearly three decades later.
If women do drink, there's widespread agreement that they should avoid having more than one drink per day. (A drink is 5 ounces of wine, 12 ounces of beer or 1.5 ounces of distilled spirits such as whiskey, tequila or vodka.) Just that amount of alcohol translates to "about a 10 percent increased risk of breast cancer," says Eric Rimm, an associate professor of epidemiology and nutrition at the Harvard School of Public Health.
More alcohol equals more risk. How much more? "Some studies suggest that two or more drinks per day are associated with about a 30 to 40 percent increase in the risk of breast cancer," says JoAnn E. Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital and a professor of medicine at Harvard Medical School. For women who have other risk factors -- a mother or sister with breast cancer, for example -- "that can be a substantial risk," Manson notes.
Just how alcohol raises breast cancer risk is something that researchers are still trying to understand. Alcohol is known to boost estrogen and other hormones, which are linked to breast cancer. In animals, alcohol has also produced some abnormalities of the mammary gland.
Mixing alcohol with hormone replacement therapy can be particularly risky, since alcohol and estrogen seem to augment each other. "That combination is something to avoid," Manson says.
But there may be ways to help cut the risk from drinking alcohol. One nutrient under investigation is the B vitamin, folic acid. Also known as folate, this vitamin gets its name from the Latin word for leaf, because it occurs in green, leafy vegetables, such as spinach, turnip greens and Swiss chard. Citrus fruits and dried beans are also rich in folate. Research suggests that women who eat a lot of fruit and vegetables have a lower risk of breast cancer.
Since 1998, the Food and Drug Administration has mandated folate fortification in grain products, such as bread and pasta, to help prevent spina bifida and other neural-tube birth defects. Folate is also a common ingredient of multivitamins and of prenatal vitamins.
Alcohol blocks folate absorption from food. So researchers have wondered whether diets high in folate might offer protection against breast cancer among women who drink. A 1998 study published in the Journal of the American Medical Association studied nearly 3,500 women with breast cancer and found no link between folate intake and overall breast cancer risk. But when researchers looked at women who had at least one drink of alcohol per day, they found that breast cancer risk was greatest among those with the lowest folate intake. "Our findings suggest that the excess risk of breast cancer associated with alcohol consumption may be reduced by adequate folate intake," the team reported.
In March, Manson and her colleagues published a report of a 10-year study of multivitamin use and breast cancer risk in nearly 40,000 women. Taking a multivitamin did not protect against breast cancer, except in women who consumed at least one drink daily. Those results "suggest that multivitamin use might help to counteract the elevated risk of breast cancer for women consuming alcohol," Manson says.
But experts say that doesn't mean that it's okay to imbibe and then pop a multivitamin or eat a lot of spinach to compensate. "There's no conclusive evidence that any vitamin or nutrient can cancel out the adverse effects of alcohol on breast cancer," Manson says. "Studies to date have been inconsistent."
Nor is there any evidence that one type of alcohol is better -- or worse -- than any other in terms of breast cancer risk. Red wine is often touted for health benefits. But there's "no clear evidence that beer or liquor is more or less likely to increase breast cancer risk than wine," Manson says.
What counts is how much you drink. Simply put, the more alcohol a woman drinks, the greater her risk of breast cancer. Or to put it another way, everything in moderation.