The question
I've heard carbonated beverages are bad for my bones. Is this true? What about sparkling water?
The answer
Some, but not all, carbonated beverages may wreak havoc on your bones if you drink them often enough. But there's no evidence that drinking sparkling water is harmful to bones. In fact, mineral water – sparkling and flat – contains naturally occurring calcium, which can benefit your bones. Cola soft drinks, both regular and diet, have been linked to weaker bones.
A 2006 study from Tufts University looked at data from 2,538 men and women in the Framingham Osteoporosis Study. Drinking at least three servings of regular or diet cola per week – versus once serving per month or less – was associated with a significantly reduced bone density at three spots in the hip in women, but not in men. (One serving was defined as one can, one glass or one bottle.) The more cola women drank, the lower their bones density was. Other carbonated beverages were not linked to bone loss.
It's not only women who should be concerned about drinking cola soft drinks on a regular basis. Studies have also found a link between these beverages and reduced bone densities in teenaged girls.
The likely cause isn't carbonation. Some researchers have speculated that soft drinks displace milk in the diet, a good source of calcium. In the Tuft's study though, there was no difference in milk intake between regular cola drinkers and non-cola drinkers.
The suspected culprit: phosphoric acid, an additive unique to cola soft drinks. It's a type of phosphorus used to a enhance flavour and preserve the freshness of colas (it's used in other processed foods too). The problem is that phosphoric acid can bind to calcium in the intestinal tract, which keeps the mineral from being absorbed into the bloodstream. If blood calcium dips too low, the body draws calcium from the bones to keep it steady.
Females may be more sensitive to the harmful effects of cola than males because they have smaller bones overall and are at a higher risk of osteoporosis. Hormonal differences may also play a role.
The occasional diet or regular cola is unlikely to rob your bones of calcium. But if you're a female who sips one most days of the week, you're bones are at risk. I suggest you kick the cola habit. On the other hand, there's no reason to stop drinking your sparkling water.
Leslie Beck, a registered dietitian, is the national director of nutrition at BodyScience Medical. She can be seen every Thursday at noon on CTV News Channel'sDirect (www.lesliebeck.com).
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Leslie Beck