It seems that a couple of cola drinks a day may be doing more than just giving you the occasional gassy belch. Recent research suggests that those tasty drinks could be compromising your bone health.

"There is enough evidence that high consumption of soda and carbonated beverages is associated with somewhat lower bone mass in children, and that's a real concern and people should be aware of it," said Dr. Lawrence Raisz, director of the University of Connecticut Center for Osteoporosis.

The exact mechanism behind the problem isn't clear, but experts believe that drinking soda -- particularly colas -- affects bone density in several ways. One reason may be that people who drink colas are simply less likely to get enough calcium and vitamin D in their diets, because the soda is replacing more nutritious beverages, such as milk or calcium-fortified juice.

Or, it could be related to the caffeine in colas, because caffeine has been linked to a higher risk of osteoporosis.

The third possible explanation focuses on one of the ingredients found in colas: phosphoric acid. Phosphoric acid can cause an imbalance in the body as the body seeks to neutralize the acid with calcium. If there isn't enough calcium in the diet, the body will take calcium from the bones.

In a study that included more than 2,500 people with an average age of about 60, researchers from Tufts University found that cola consumption by women was associated with lower bone mineral density at three hip sites, regardless of age, menopause, total calcium and vitamin D intake. The women reported drinking an average of five carbonated drinks a week, four of which were colas.

Results of the study were published recently in the American Journal of Clinical Nutrition.