DEAR DOCTOR K:
I know I should drink plenty of water every day, but sometimes I get tired of drinking plain water. So I reach for club soda, seltzer water or sparkling mineral water. But I’ve heard that carbonated drinks could be bad for my bones. Is this true?
Several of my patients have asked the same question. Sometimes they are not asking about carbonated water, but carbonated beverages that contain caffeine (like colas) and sugar or sweetener. I’ll tell you what I tell them.
There is a theory that phosphoric acid (phosphate), found in some carbonated beverages, can interfere with calcium absorption. But there’s no good evidence that consuming a lot of phosphate affects bone metabolism or bone density. Researchers have looked at the effect of carbonated beverages on bone health in adults. One study found that non-cola carbonated drinks (like the carbonated water drinks you asked about) were not associated with low bone density.
Another study compared two groups of healthy postmenopausal women. Both groups drank one quart of either carbonated or non-carbonated mineral water per day. After eight weeks, there was no difference in bone turnover between the two groups. So I don’t put much stock in the theory that carbonated water weakens your bones.
On the other hand, in the same study I just talked about, women who drank cola had lower hip bone density. The more cola a woman drank, the lower her bone mineral density (BMD). Some scientists suspect that the caffeine in cola may have a harmful effect on BMD, but there’s no proof of that.
So the good news is that drinking carbonated water doesn’t appear to be bad for your bones. On the other hand, don’t overdo the caffeinated beverages, carbonated or not. And make sure that carbonated water isn’t taking the place of other healthy beverages in your diet, such as calcium-rich, low-fat milk.
Finally, in talking about the carbonation in carbonated beverages, let’s not forget about the real culprit that makes some types of carbonated beverages unhealthy: sugar.
A few years ago a patient of mine asked me if the carbonation in the 10 cans of cola she drank a day was bad for her bones. I told her that the carbonation in colas might be a problem for her bones, but that was the least of her problems with colas. The sugar in all those colas was a definite problem for her whole body. The weight gain associated with sugary sodas puts a big strain on the heart, blood vessels and joints.
So my advice is to feel free to enjoy carbonated water without worrying. However, I reserve the right to change my mind, when and if new evidence emerges. And if it does, I’ll let you know.