A US study has claimed that drinking cola could weaken bones in women and could lead to increased risk of osteoporosis.

Experts at the Jean Mayer USDA Human Nutrition Research Centre in the US state of Massachusetts said that drinking cola led to lower bone mineral density in women's hips, although cola was not linked to weaker bones in men's hips or the spines of both sexes.

The experts studied the bone density of over 2,500 people aged just under 60. Lead researcher Dr Katherine Tucker said: "The more cola that women drank, the lower their bone mineral density was.

"However, we did not see an association with bone mineral density loss for women who drank carbonated beverages that were not cola."

Dr Tucker called for further studies to work out if taking in phosphoric acid, found in cola, was to blame.

She said there was no concrete evidence that an occasional cola harms the bones, but added: "Women concerned about osteoporosis may want to steer away from frequent consumption of cola until further studies are conducted."

However, the British Soft Drinks Association said that experts who study osteoporosis pointed to an unbalanced diet, lack of exercise, drinking alcohol and smoking as the main causes for the bone disease.

A spokesman told just-drinks today (6 October): "The scientific evidence does not suggest that phosphate, used in the form of phosphoric acid in some carbonated drinks, has a detrimental effect on bone health.

"In any case, soft drinks provide only 3% of total phosphorus intake from dietary sources, the two main sources being cereals and cereal products, and milk and milk products."

The spokesman added: "Consumers can continue to enjoy drinking cola drinks as part of a balanced diet. Carbonated drinks can be included within the 2 litres of fluid everyone should aim to consume each day to stay properly hydrated."