Vitamin D supplementation lowers fracture risk

Researchers have found that doses of 700 to 800 IU of vitamin D3 per day may reduce the risk of hip fracture by 26 percent and nonvertebral fracture by 23 percent.

The May 11 2005 issue of the Journal of the American Medical Association published the results of a meta-analysis of 12 clinical trials involving vitamin D supplementation in the prevention of fracture. The analysis concluded that supplementation with higher than the commonly recommended 400 international unit (IU) doses of vitamin D reduces the risk of hip and nonvertebral fractures in older individuals.

The vitamin D studies included a total of 19,114 men and women aged 60 and older. The trials used the form of the vitamin known as cholecalciferol, or vitamin D3, which, according to studies cited in the current review, may be much more effective than the dietary form of the vitamin.

The researchers found that doses of 700 to 800 IU of vitamin D3 per day reduced the risk of hip fracture by 26 percent and nonvertebral fracture by 23 percent. Studies that used 400 IU vitamin D3 or less found no significant benefit for either type of fracture. The role of additional calcium supplementation could not clearly be defined from the studies, but it appears that at least 700 milligrams calcium per day may also be necessary for nonvertebral fracture prevention.

JAMA 2005 May 11;293(18):2257-64.

Supplemental vitamin D and calcium reduces risk of diabetes

The incidence of type-2 diabetes is lower among women who get adequate calcium and supplement with vitamin D. Researchers used data from the Nurses Health Study, which includes over 83,000 women, to study the relationship of calcium and vitamin D intake to type-2 diabetes.

After 20 years of follow-up, it was concluded that a combined daily intake of over 1,200 mg of calcium and more than 800 IU of vitamin D was associated with a 33 percent lower risk of type-2 diabetes. Interestingly, dietary vitamin D intake did not appear to provide any statistically significant benefit. But the women who supplemented with at least 400 IU of vitamin D had a 13% lower risk of diabetes when compared to those who took less than 100 IU per day. Both dietary and supplemental calcium resulted in decreased risk of type-2 diabetes, and those with overall intakes above 1,200 mg had a 21% lower risk than those who got less than 600 mg per day.

Elevated intakes of calcium and vitamin D, especially from supplements, are significantly associated with lower incidence of type-2 diabetes.

Diabetes Care 29:650-656, 2006

Vitamin D reduces the risk of certain cancers

A study published in the American Journal of Public Health, has found that vitamin D deficiency may account for several thousand premature deaths annually. The researchers reviewed 63 studies on the relationship between vitamin D and certain types of cancer worldwide between 1966 and 2004. The majority of studies found a protective relationship between sufficient vitamin D status and lower risk of cancer, especially in cancers of the colon, breast, prostate and ovary.

Vitamin D is acquired either through the diet or through exposure to sunlight. Food sources include milk, yogurt, cheese, and fortified orange juice. A typical serving provides approximately 100 international units (IU). Researchers suggested that people might want to consider a vitamin supplement to raise their overall intake to 1,000 IU's per day. Supplementing with additional vitamin D could be especially important for people living in northern areas, which receive less vitamin D from sunlight.

The evidence suggests that improving vitamin D status through diet and supplements could reduce cancer incidence and mortality at low cost, with few or no adverse effects.

American Journal of Public Health February 2006, Vol 96, No. 2:252-261.