A new US study reports that a daily supplementation with calcium and vitamin D may help to increase bone density of people with a higher risk of skeletal stress fractures due to intense physical fitness training.
In the randomized controlled trial, bone mineral density and content were measured in 156 male and 87 female military recruits who received 2,000 milligrams of calcium and 1,000 IU of vitamin D per day or placebo for nine weeks of basic combat training (1). The study results showed that the supplementation was associated in a significant increase in bone mineral density and bone mineral content, compared to placebo. In addition, the participants in the supplement group showed consistent blood levels of parathyroid hormone (PTH) during the training, which is an important result since PTH has been reported to increase during training and this has been linked to stress fractures.
The researchers noted that these findings indicate a beneficial effect of vitamin D and calcium on bone geometry and strength potentially reducing the risk of stress fractures during stressful physical demands. Basic military training, for example, puts a lot of stress on the skeleton and often results in injury: between 2% and 5% of men and 8% and 21% of women are reported to suffer from a stress fracture during initial military training.