To keep bones strong, try vitamin D
Vitamin D -- the fat-soluble vitamin that’s technically a hormone -- is crucial for good bone health. Manufactured in the skin with the help of the sun’s ultraviolet B rays, the vitamin regulates absorption and excretion of calcium. Because it’s found in very few foods (fatty fish and cod liver oil are on the short list), most Americans, particularly the sun-deprived, get the vitamin from fortified milk and cereal products.
Uses: Vitamin D supplements are commonly taken to help prevent osteoporosis, bone loss and fractures in older adults. Some people also take the vitamin in attempts to fend off cancer and treat mood disorders, such as seasonal affective disorder, and for relief from psoriasis.
Dose: The Food and Drug Administration recommends an average daily dose of 400 international units, and 600 IUs for adults over 70. Over-the-counter vitamin D supplements come in tablet and capsule form.
Precautions: Vitamin D supplementation is generally safe. Long-term use of high doses (1,000 IUs per day or more) can cause hypercalcemia, or excess calcium in the blood, a condition signaled by nausea, weakness, constipation and headaches, among other symptoms.
Research: Several studies have shown a higher risk of osteoarthritis and bone fracture in people with low vitamin D levels. Others have shown that a lack of vitamin D hampers bone mineralization, which may increase fractures and may be linked to muscle weakness.
Although a recent study published in the Journal of the American Medical Assn. showed that daily vitamin D supplements did not protect against bone loss in black women over 50, some clinical trials suggest that vitamin D’s effectiveness against bone loss and fractures in the elderly may be amplified when the vitamin is taken in conjunction with calcium.
Suggestions that vitamin D can help protect against prostate, colorectal and other forms of cancer come largely from laboratory and animal studies, so it’s too soon to draw conclusions about its effects in humans. Evidence for the vitamin’s effectiveness in treating seasonal affective disorder is also inconclusive, but a study published in June in the Archives of Internal Medicine showed that women with diets rich in vitamin D and calcium experienced fewer physical and emotional symptoms typically associated with premenstrual syndrome.
Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your healthcare provider for advice on selecting a brand.
