A study indicates that moderate drinking, particularly of beer and wine, can help protect older bones against osteoporosis, a condition that increases the risk of fractures and disability.
But researchers are being cautious about how they report the results of this study, which was published in the February 25, 2009, issue of The American Journal of Clinical Nutrition.
The finding that regular drinking may be good for bones comes on the heels of another large, well-designed clinical trial that followed 1.3 million women for more than a decade and found that any amount of alcohol consumption in women raised their risk of breast, liver and rectal cancers.
That study, by British researchers, was published in the March 4, 2009 issue of The Journal of the National Cancer Institute.
“It’s not a simple message of alcohol is good,” says Katherine Tucker, PhD and professor of nutritional epidemiology at Tufts University in Boston, who led the international team behind the bone health study. “The tricky part is we actually found with wine, the women who were drinking three glasses a day had the highest bone density and that’s not moderate. The current definition of moderate is 1 to 2 a day. That's still the safest recommendation."
Earlier research had suggested a link between moderate drinking and improved bone density. This new study took the research one step further, specifically looking at the possible effects of three types of alcohol – beer, wine and liquor.
To do that, researchers recruited 1,182 men, 1,289 post-menopausal women and 248 pre-menopausal women who were given bone mineral density (BMD) tests of their spine and three places on their hips. Participants then filled out questionnaires about their alcohol and dietary habits.
Dr. Tucker says her team discovered stronger associations between higher BMD and beer drinkers, who were mostly men, and wine drinkers, who were mostly women.
“What we found and what is consistent with other research is that there are some health benefits to moderate consumption,” Dr. Tucker says, “Particularly of beer and wine because they have other natural constituents that can be beneficial."
Because there was not enough data to measure the effect of moderate beer and wine drinking on women before menopause, the finding does not apply to all age groups, Dr. Tucker says.
And researchers cannot say exactly what parts of an alcoholic drink aid bone health because their findings are from an observational study. But they hypothesize that orthosilicic acid, a major constituent of beer, and antioxidants in grapes could contribute to higher BMD scores They say more research is needed to determine that for sure.
The study did find that cocktails and strong spirits don’t produce similar positive results, at least in men. Men who were drinking more than two drinks of hard alcohol had the lowest bone density of those studied.
Women, confusingly, were another story. Across all categories – wine, beer, and liquor – those in the highest category for consumption, defined as having two or more drinks a day had the highest bone densities. Wine appeared to convey the biggest benefit. Women who reported drinking more than two glasses of wine a day had, on average 8.3 percent greater bone density at the spine and 10.7 percent greater bone density at the hip than those who did not drink at all.
Despite those findings, the study’s authors say that women should not boost their alcohol intake to shore up their bones, and they further caution that excessive drinking of any kind can have dire consequences, making bones weak and raising the risk of fractures.
Plus, while alcohol may protect against bone loss, excessive drinking in older people poses other risks, such as increasing the chance of falls.
“If you have osteoporosis and are already moderately drinking beer and wine, it’s OK to keep doing that,” Dr. Tucker says. “In fact, there is a noticeable, significant protective effect against bone. But it has to be balanced against the risks,” of cancer and other diseases, she explains.
Amarjit Virdi, PhD, an assistant professor in the Department of Anatomy and Cell Biology at Rush University Medical Center in Chicago says while the focus on components of alcohol is a strength of this research, he finds it significant that the study is not longitudinal.
Rather than following the same people over time, it was a cross sectional study, which looked at a number of different people who could have a variety of backgrounds and lifestyles.
"There are lots of compounding factors which mess up the message. Whereas if you follow the same people over time, other factors are relatively consistent," Dr. Virdi said. "If they did a longitudinal study, they would get a much stronger correlation. The data would be stronger and the conclusions would be more solid. They would have cleaner data."