This is important news. Researchers found that athletes that have a low Vitamin D consumption, had a much higher incidence of having stress fractures when participating in high impact sports. Calcium and Dairy products did not have an effect on stress fractures. Vitamin D is produced in the skin from ultra-violet light. It is found in some cold weather fish and some enriched foods such as milk and bread. Considering that sunlight exposure is substantially decreased after x-country season (shorter daylight hours and less sun exposure from indoor training), vitamin D production is barely produced, creating a deficiency. It is recommended to get from 20 minutes to one hour of sunlight every day, 20 minutes for light skin, more for darker skin. Face, arms & legs should be exposed, weather permitting. Can't get out side take Vitamin D3 supplements. Make sure to talk to your doctor about it and make it a great day!
reference: March 5 issue of the “Archives of Pediatric & Adolescent Medicine”