It's well-known that exercise is good for our bones, even as we age, but how about that nightly glass of wine?
A new study of women in their 50s and early 60s finds that moderate alcohol consumption may help prevent bone loss. The women in the study consumed about 1 1/2 drinks per day.
The findings fit with previous studies, including the Framingham Heart Study, which documented that moderate drinkers — people who consume one to two drinks per day — have higher bone mineral density compared with heavy drinkers and people who don't consume alcohol at all.
But sorry guys, this one's just for the ladies.
The latest study, published in the journal Menopause, finds evidence that moderate alcohol consumption influences bone turnover. It's a small study, just 40 women, but it helps explain why this may be the case.
Our bodies are constantly in the process of remaking bone. Bits of bone are dissolved (or resorbed, to borrow researchers' technical term), and then new bone is formed.
During menopause, the rate of resorption increases, according to researcher Urszula Iwaniec of Oregon State University. "And the formation [of new bone] doesn't keep up with resorption." As a result, bone loss can occur.
To figure out what happened to the women's bones during the study, Iwaniec and her colleagues took blood samples to measure specific byproducts of bone remodeling. Basically, when bone dissolves, little bits of protein that were part of the bone spill into the bloodstream.
"And these [markers] correlate with the amount of bone that is resorped," explains Iwaniec.
The researchers first took blood samples of women who had been regularly consuming alcohol (most were wine drinkers). Then, they took blood samples two weeks later, after the women were told not to drink for those two weeks.
"What we found was that the [blood] markers were higher, significantly higher [after the women stopped drinking]," explains Iwaniec. "Indicating that more bone was being resorped," she says.
But once the women went back to the nightly glass of wine? The blood markers dropped back to where they'd been before.
In other words, the alcohol seemed to slow down the bone turnover rate, which may over time protect against fractures.
The risk of any study that concludes that alcohol consumption may be beneficial is that we'll get carried away. If we hear that a drink a day is good for us, it's easy to think: Hey — two or three drinks sound even better!
"Many people don't interpret studies like this correctly," says John Callaci, director of the Molecular and Cellular Bone Biology Laboratory. He has studied the deleterious effects of binge-drinking on bones.
Seven to nine drinks spread out over the course of a week may be beneficial for women's bone health, as this study suggests, Callaci says. But it's not a message you'd want to send to people under the age of 25 who are still building bone mass.
"Anything that might interrupt that process of bone-mass accrual would be bad [for young people]," says Callaci. "So I would definitely not extrapolate these results to younger people or anybody outside the confines of the study.
Researcher Iwaniec agrees. She says her next step is to repeat the experiment in a much larger group of women, to see if she can confirm her findings.
STEVE INSKEEP, HOST:
Researchers are learning more about the effects of alcohol consumption on bone health. It's been known for some time that binge drinking really takes a toll on bones, among other things. But a new study of moderate drinkers finds there may be a benefit to a nightly glass of wine - at least for some people. NPR's Allison Aubrey reports.
ALLISON AUBREY, BYLINE: The bones that you and I have in our bodies are not technically the same ones that we had a decade ago. Our bodies are constantly in the process of remaking bones through a process that scientists call resorption where bits of bone dissolve and then formation where new bone is rebuilt. Researcher Urszula Iwaniec of Oregon State University says this process is healthy, but by the time women reach the age of 50 or so, it can get out of whack.
URSZULA IWANIEC: With menopause, that rate of replacement, that rate of turnover, is elevated. And so the formation does not keep up with the resorption, and as a result bone loss occurs resulting in osteoporosis.
AUBREY: Iwaniec and her colleagues wanted to know how moderate alcohol consumption might influence this process. They had a hunch there could be a benefit since the few large studies have shown correlations between women who consume about a drink a day and better bone health. So, they recruited about 40 women in their 50s and early 60s - mostly wine drinkers - and tested what happened when they stopped drinking.
IWANIEC: So, these women were asked to continue their normal daily activities for the two weeks. The only thing that they were asked to do was to abstain from alcohol intake.
AUBREY: To gauge what was happening in their bones, researchers took blood samples to measure specific byproducts of bone remodeling. Basically, when bone dissolves, little bits of protein that were part of the bone spill into the bloodstream.
IWANIEC: And these correlate with the amount of bone that is resorped.
AUBREY: Or being lost. Iwaniec says after only two weeks of abstaining from alcohol, the women's blood markers changed quite a bit.
IWANIEC: What we would found was that the markers were higher, significantly higher than while they were drinking, indicating that more bone was being resorped.
AUBREY: Meaning more bone was likely being lost. But once the women went back to the nightly glass of wine, the blood markers dropped back to where they'd been before. In other words, the alcohol seemed to slow down the bone turnover rate, which over time may protect against fractures.
IWANIEC: We are pretty sure that it is the alcohol because that is the only thing we were controlling for.
AUBREY: This is certainly not the first study to suggest that moderate drinking may be beneficial. In addition to relieving stress, large studies show one to two drinks per day may be good for heart health. But there are also risks, such an increased risk of breast cancer. And as bone researcher John Callaci of Loyola University points out, when people hear about a study that finds one drink a day is healthy for you, they may think, hey, two or three drinks sounds even better.
JOHN CALLACI: Many people don't interpret studies like this correctly.
AUBREY: He says seven to nine drinks spread out over the court of a week may be beneficial for women's bone health, as this study suggests. But for younger people under the age of 25 who are still building bone mass.
CALLACI: Anything that might interrupt that process of bone mass accrual would be bad. So, I would definitely extrapolate these results to younger people or anybody outside the confines of this study.
AUBREY: Researcher Urszula Iwaniec agrees. And she says her next step is to repeat the experiment in a much larger group of women to see if she can confirm her findings. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright National Public Radio.