By Howard LeWine, M.D.
Q: Do all carbonated beverages rob the bones of calcium? How about club soda or sparkling mineral water?
A: Warnings about the harmful effects of carbonated beverages on bone emerge from time to time. The theory is that the phosphoric acid (phosphate) used to enhance flavor in some carbonated beverages can interfere with calcium absorption and result in the loss of calcium from bone. Fortunately, there’s no good evidence that a high phosphate intake affects bone metabolism or bone density.
Teenage girls who drink a lot of carbonated beverages are more likely to have lower-than-expected bone density. But that’s most often because of insufficient intake of healthier beverages that provide calcium and vitamin D.
The picture is less clear in adults. Researchers at Tufts University examined data from 2,500 women and men (ages 49 to 69). They assessed dietary intake and measured bone mineral density (BMD). Non-cola carbonated drinks were not associated with low BMD.
Cola and other caffeinated beverages are still suspects. In the Tuft’s study, cola intake was associated with lower BMD at the hip in the women, but not in the men. The more cola a woman drank, the lower her BMD. Women who drank more cola didn’t drink less milk, but they did have a lower intake of calcium.
We have less direct information regarding carbonated water. The results of one small study comparing bone metabolism in women who drank noncarbonated vs. carbonated mineral water showed no difference between the two groups.
It seems likely that you can enjoy carbonated water without worry. But don’t overdo the caffeinated beverages, whether carbonated or not. And if you suspect that you are drinking a lot of carbonated water or other soft drinks, you may be reducing your intake of healthy beverages. Make sure you get enough calcium (1,000 to 1,300 milligrams per day) and vitamin D (600 to 1,000 IU per day) from other sources to compensate.
(Howard LeWine, M.D., is an assistant professor of medicine at Harvard Medical School.)
(For additional consumer health information, please visit www.health.harvard.edu.)