Researchers from Tufts University, led by director of epidemiology Katherine Tucker, examined dietary questionnaires and bone density measurements of more than 2,500 people whose average age was just younger than 60. Bone mineral density measurements were taken from the spine and three different sites on the hips.
The researchers found that in women, consumption of carbonated cola beverages was associated with lower bone mineral density at all three hip measurement sites. The results took into consideration the women's age, calcium and vitamin D intake, menopausal status and use of cigarettes or alcohol.
However, the researchers did not see the same association between colas and bone density in men, who reported drinking an average of six carbonated beverages per week -- five of which were colas. The study authors were unclear on why colas seemed to affect women more than men.
"The more cola that women drank, the lower their bone mineral density was," the authors wrote. The researchers did not find an association between non-cola carbonated drinks and bone loss, which they attribute to the fact that colas contain phosphoric acid, which is not found in non-cola drinks. Diets low in calcium and high in phosphorus can promote bone mineral loss, the researchers wrote.
"Further controlled studies should be conducted to determine whether habitual cola drinkers may be adversely affecting their bone health by regularly consuming doses of phosphoric acid that do not contain calcium or another neutralizing ingredient," the researchers wrote, adding that "women concerned about osteoporosis may want to steer away from frequent consumption of cola until further studies are conducted."
Natural health advocate Mike Adams, author of "The Five Soft Drink Monsters," says carbonated sodas -- especially colas -- are highly acidic. "In order to buffer that acidity, the body strips minerals like calcium from the skeletal system, thereby reducing the mineral density of bones," Adams said. "This is how soda consumption directly promotes osteoporosis."