Vitamin D and Bone Health

Written by Gloria Tsang, RD
last updated: January 2006

Not just Calcium - Vitamin D is just as important

Many of us are aware of the importance of calcium and its role in osteoporosis prevention. However, we sometimes neglect an essential co-factor in bone health management - Vitamin D.

Vitamin D promotes the absorption of calcium and phosphorus. It regulates how much calcium remains in your blood and how much is deposited in bones and teeth.

Osteoporosis is most often associated with inadequate calcium intake. However, a deficiency of vitamin D also contributes to osteoporosis by reducing calcium absorption. According to the National Institutes of Health, people with vitamin D insufficiency absorbs less than 10% of available calcium. In other words, even if you have an adequate calcium intake, you may not absorb it effectively if you have low levels of vitamin D. Indeed, researchers from the Harvard Medical School published results of a large-scale study in the American Journal of Clinical Nutrition in February 2003 confirming this. The study concluded that there was a lower risk of hip fractures only in individuals with a higher intake of calcium coupled with a higher intake of vitamin D.

Vitamin D - How much?

Average adults including pregnant women need 200 IU of vitamin D daily while adults over 50 need 400 IU daily. The recommendation for vitamin D intake further increases to 600 IU for people over 70 years of age.

Vitamin D insufficiency is common among people over 50, with reported prevalences between 25% and 50% of the population. Insufficiency rate is even higher among elderly living in nursing homes. Non-institutionalized older adults, however, are still at risk of vitamin D insufficiency if they live in the northern region where sun exposure is limited. A report published by Danish researchers in March 2004 showed that daily supplementation of 400 IU of vitamin D can reduce the risk of bone fractures in non-institutionalized elderly living in the northern European region.