About 90 percent of hip fractures involve falls. Therefore, prevention of falls is crucial for prevention of hip fractures. And vitamin D is crucial for prevention of falls. That is the conclusion of a study published by H. A. Bischoff and other researchers in the Journal of Bone and Mineral Research in February 2003. In this study 122 elderly women, whose average age was about 85, were divided into two groups. One group received 1,200 milligrams of calcium plus 800 international units of vitamin D. The other group received 1,200 milligrams of calcium alone for twelve weeks.

The calcium-plus -vitamin D treatment resulted in 49 percent reduction in the incidence of falls compared with the calcium treatment alone.

How Vitamin D Prevents Falls

How can vitamin D prevent falls? By increasing muscle strength. In this same study, muscle function improved significantly in the calcium-plus-vitamin D group compared with the calcium-alone group. Many other studies support the connection between vitamin D and muscle function. Previous research has shown that vitamin D deficiency results in muscle weakness and impaired balance. Muscle weakness and impaired balance increase the risk of falls.

Muscle Weak ness: A Risk Factor for Falls

Numerous studies attest to muscle weakness as a risk factor for falls. In a study published in the July 2004 issue of the Journal of the American Geriatric Society, a research team led by J. D. Moreland evaluated and summarized the evidence from thirteen different studies of muscle weakness as a risk factor for falls in older adults. In these studies that met the highest standards for research methods employed, muscle weakness was found to be a consistent risk factor for falls among older adults, especially for recurrent falls. Muscle strength in older adults was evaluated through various criteria such as gait, body sway, ability to stand on one foot, ability to stand from a sitting position without using the arms, grip strength, quadriceps strength, leg extension strength, and ability to climb stairs.

Vitamin D Deficiency and Muscle Weakness

Vitamin D deficiency plays a role in sarcopenia, the loss of muscle mass and muscle strength with aging. A study, also published in the Journal of the American Geriatric Society in February 1999 by Mowe and others, found that older people with reduced muscle function often had reduced serum concentrations of vitamin D. This finding was corroborated by a study published in December 2003 in the Journal of Clinical Endocrinology and Metabolism. Visser and other authors of the study found that low levels of vitamin D increased the risk of sarcopenia in older men and women: in men and20women 65 years and older, those with low levels of vitamin D were more than twice as likely to experience sarcopenia as those with high levels of vitamin D. A review article by Janssen and others in the American Journal of Clinical Nutrition, April 2002, entitled “Vitamin D deficiency, muscle function and falls in elderly people,” reported that vitamin D deficiency affects predominantly the weight-bearing antigravity muscles of the lower limbs, which are necessary for postural balance and walking. The article also reported that low serum concentrations of vitamin D have been correlated with the occurrence of falls in elderly people.

More Vitamin D: More Muscle Strength

Conversely, high serum concentrations of vitamin D are associated with greater muscle function. In a study published in the American Journal of Clinical Nutrition, September 2004, Bischoff-Ferrari and other researchers found that in both active and inactive adults aged 60 and over, those with the highest concentrations of vitamin D had significantly better muscular function in the lower extremities than those with the lowest concentrations of vitamin D.

There is biochemical evidence for the connection of vitamin D and muscle function: vitamin D receptors have been found in skeletal muscle cells both in animal models and in humans. (American Journal of Clinical Nutrition, April 2002).

How To Get Your Vitamin D

The best food sources of vitamin D are fish liver oils, the most familiar being cod liver oil. Fatty fish such as salmon, herring, mackerel, and sardines are also good sources. Vitamin D occurs in lesser amounts in butter, cream, and eggs. Vitamin D is also found in shrimp and the skin of poultry.

But the best source of vitamin D overall is the sun. Vitamin D is made in the skin, with the help of essential fatty acids, in the presence of sunlight. Exposure to sunlight for as little as 20 to 30 minutes a day should be enough vitamin D for our bodies. So for your daily dose of vitamin D, take a walk on the sunny side of the street, but watch your step.

Mary Lou Williams, M. Ed., is a writer and lecturer in the field of nutrition. She welcomes inquiries. She can be reached at (239) 267-6480.