Introduction

In this study, 98 postmenopausal women scheduled for hip replacement living in the Boston area were recruited. Thirty of them were admitted because of hip fractures. Sixty-eight were due to have elective hip replacement for a variety of reasons -17 had osteoporosis and 51 did not. All participants provided information regarding their lifestyle, reproductive history, dietary calcium intake, and physical activity.

Study Findings

Half the women admitted for acute hip fractures had significantly lower vitamin D levels compared to those who were admitted for elective hip replacement, regardless or whether they had osteoporosis. Vitamin D is required for efficient absorption of dietary calcium and normal mineralization of the bone.

Low levels of vitamin D are associated with decreased calcium absorption and an increase in parathyroid hormone. Increases in parathyroid hormone in turn can cause bone loss. Women with hip fractures in this study also had significantly higher levels of parathyroid hormone than both groups of women admitted for elective hip replacement. Other indicators of "bone turnover" were also significantly greater in women with hip fractures than in women without osteoporosis who had elective hip replacement.

More Focus on Vitamin D Needed

Advancing age is associated with a decreased intake and ability to absorb vitamin D. Decreased exposure to the sun, which activates vitamin in the skin, also accompanies aging. The National Institutes of Health recommends that people age 51 to 70 consume 400 IU vitamin D per day. Individuals over age 70 are advised to consume 600 IU per day. These recommendations are double and triple earlier recommendations.

The authors of this study conclude that vitamin D deficiency exists in postmenopausal women with hip fractures living in the northeast. Adequate amounts of vitamin D, either through supplements or increased sun exposure, may reduce the increased risk for fractures that accompany aging. Restoring vitamin D levels to normal at the time of the fracture may also facilitate hip repair and reduce the risk for future fractures. Supplementation of about 800 IU per day and calcium may be necessary to slow bone loss, according to the authors.

Reviewer Comment

Vitamin D plays an important role in helping us absorb calcium and deposit it in bones. Milk is the only food that is fortified with vitamin D, with one cup containing about 100 IU of vitamin D. It's best to choose food first to meet vitamin D requirements. In addition to vitamin D, milk contains other essential nutrients, including protein and calcium. Most multivitamin supplements preparations for people over age 50 contain 400 IU vitamin D. When combined with an adequate diet that includes 2 to 3 eight-ounce serving of milk, vitamin D recommendations can be met. Supplementation over and above a multivitamin preparation should always be done under the supervision of a registered dietitian or qualified health care provider. Supplemental levels should never exceed 2000 IU per day.