As a part of their study, the researchers analysed data of 400 women enrolled in the Women's Health Initiative Observational Study Cohort who had experienced hip fracture, confirmed by their medical record, over a median of 7.1 years.
The researchers compared the levels of 25 hydroxyvitamin D, an indicator of vitamin D status, in the bloodstream of these women to a control group matched for age, race, ethnicity and the date of relevant blood work.
The team found that as the concentration of vitamin D decreased in a woman's body, the risk of hip fractures climbed, and that women with the lowest concentration of the nutrient were at a 77 percent higher risk of having a fracture.
"The risk of hip fractures was 77 percent higher among women whose 25 hydroxyvitamin D levels were at the lowest concentrations," said Dr. Cauley.
"This effect persisted even when we adjusted for other risk factors such as body mass index, family history of hip fracture, smoking, alcohol use and calcium and vitamin D intake," she added.
Vitamin D deficiency early in life is associated with rickets - a disorder characterized by soft bones. Though the exact daily requirement of vitamin D has not been determined, most experts think that people need at least 800 to 1,000 international units a day.
Many experts believe the current recommended levels of 400 IUs daily should be increased.
The vitamin is manufactured in the skin after sun exposure, and is not available naturally in many foods other than fish liver oils. Some foods are fortified with the vitamin.
The study was presented this week at the 29th annual meeting of the American Society for Bone and Mineral Research at the Hawaii Convention Center.