All of the women were daily or near-daily moderate drinkers, defined in the study as having one-half to two standard drinks per day. Most of the women preferred wine; in America, a standard drink of wine is defined as a 5oz. glass, of which there are about five in a typical bottle.
For the study, the women were asked to abstain entirely from alcohol for two weeks, and then start drinking again for two days. Researchers tracked certain blood markers of bone health throughout, and found that these markers of bone density correlated positively with alcohol consumption: in other words, the more the women drank within the moderate range, the better their bone health looked.
During their period of abstinence, the scientists saw negative changes in measures of bone formation and resorption. “There was a significant increase in the bone turnover markers osteocalcin and CTx when alcohol was excluded for 14 days,” the authors write. That is, when the women weren’t drinking, their bones were breaking down more than they were being rebuilt.
But when they started drinking again, the healthier levels were restored. “Within 12-14 hours of resuming alcohol consumption, osteocalcin and CTx returned to values that did not differ from baseline,” the authors note, concluding that the “small but significant increases in [these chemicals] after short-term abstinence provide substantial evidence that moderate alcohol consumption decreases bone turnover.”
“Drinking moderately as part of a healthy lifestyle that includes a good diet and exercise may be beneficial for bone health, especially in postmenopausal women,” said lead author Urszula Iwaniec in a statement. “After less than 24 hours to see such a measurable effect was really unexpected.”