Low Vitamin D Raises Women's Hip Fracture Risk

Too many Americans aren't getting enough of the sun-sourced nutrient, researchers say

By Steven Reinberg
HealthDay Reporter

MONDAY, Aug. 18 (HealthDay News) -- Low levels of vitamin D can boost older women's risk for hip fracture by more than 70 percent, University of Pittsburgh researchers report.

The finding adds weight to the recommendation that people maintain adequate intake of vitamin D, which is primarily made by the skin when it is exposed to sunlight.

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The fracture-vitamin D link "has been observed for 15 years," noted Dr. Michael F. Holick, director of the Vitamin D Skin and Bone Research Laboratory at Boston University. "The good news is it's consistent, the higher your vitamin D status, the lower the risk of your developing a hip fracture."

The new report appears in the Aug. 19 issue of the Annals of Internal Medicine.

Hip fractures can be devastating for older individuals. In fact, 50 percent of older people who suffer a hip fracture will end up in a nursing home and 20 percent will die within the first year due to complications such as a pulmonary embolism resulting from the fracture, Holick said.

For this study, a research team led by Jane A. Cauley from the University of Pittsburgh collected data on 800 women aged 50 to 79. Researchers followed the women for up to nine years to determine their risk for hip fractures.

They found that the risk of hip fracture rose 33 percent with every 25 nanomoles per liter drop in vitamin D levels. Women with the lowest levels of vitamin D had a 71 percent increase risk for hip fractures compared with women with the highest levels of vitamin D, the researchers report.

"We conclude that low serum vitamin D concentrations are associated with an increased risk for hip fracture in community-dwelling women. The mechanism of association is unclear," the authors wrote.

Holick notes that vitamin D is essential for the body's absorption of calcium, a key component of bone health. "If you don't have adequate vitamin D, you cannot efficiently absorb calcium," he said. "Vitamin D also helps maintain bone health by keeping bone cells active."

According to the U.S. Institute of Medicine, people should get between 200 and 400 international units of vitamin D a day. The best way to get vitamin D, naturally, is by being out in the sun.

As little as 10 to 15 minutes of sun a day can give you all a vitamin D you need. Vitamin D is also available in small quantities in foods such as fish and milk.

Preventing hip fracture is another good reason to keep your vitamin D levels up, Holick said. "To get vitamin D levels to where they need to be to reduce the risk of hip fracture, you need to be taking at least 1,000 international units of vitamin D a day from a supplement," he advised.

Dr. John Jacob Cannell, executive director of the nonprofit Vitamin D Council, agreed that most people are not getting enough of the nutrient.

"Women need to know their vitamin D status," Cannell said. "They need to ask their doctor for the right test," known as the 25 hydroxy D test. "Women should strive to keep your vitamin D levels above 125 nanomoles per liter, year round. To do that, they are going to require supplements."

Cannell recommends that before they get a blood test for vitamin D, women take 2,000 international units of vitamin D a day for three months.

More information

For more about vitamin D, visit the U.S. National Institutes of Health.