A team of scientists from Boston have published a study showing that cola drinks may cause bone loss in older women. The Framingham Osteoporosis Study took bone measurements in over 1,400 women. Their diets were assessed and results showed that the more cola they drank, the more bone was lost from the hip (but not the spine). Similar results were seen for diet-cola, but not for non-cola fizzy drinks. Scientists have suggested several possible reasons why this happens. The phosphoric acid in cola may be to blame, or it may be that cola is drunk in place of healthier drinks that contain calcium, such as calcium-fortified soya milk.
Tucker KL, Morita K, Qiao N, Hannan MT, Cupples LA and Kiel DP. 2006. Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study. American Journal of Clinical Nutrition. 84 (4) 936-942.