A Vitamin for Better Bones?

Osteoarthritis is a degenerative disease in which the cartilage and tissue around a joint break down and cause pain and loss of mobility. About 27 million American adults have osteoarthritis; the prevalence of this "wear and tear" condition increases with age, with sufferers typically noticing symptoms after the age of 40. By age 65, a full third of people have symptoms. The condition affects mostly the knees, hips, spine, and hands, but it can occur in any joint.

The bad news? Osteoarthritis cannot be cured. However, there are effective treatments to can help relieve pain and stiffness and restore mobility to the affected joint(s). These include range-of-motion exercises, gentle stretching, weight loss (to reduce the burden on already fragile joints) and anti-inflammatory pain relievers (such as ibuprofen and naproxen). And it’s also possible that vitamin D might just ease the symptoms of osteoarthritis, particularly in overweight sufferers.

In a recent study, researchers at the University of Florida looked at 256 middle-aged and older people, about half of whom were obese. They observed participants balancing, walking, and rising from sitting to standing; questioned them about the severity of their knee pain—and took blood samples to measure their vitamin D levels.

All of the subjects with adequate vitamin D levels reported less osteoarthritis-related knee pain than those who were vitamin D-deficient. And overweight subjects who had plenty of D demonstrated more knee mobility and had better lower-body range of motion than overweight subjects who lacked the vitamin, according to Toni Glover, PhD, assistant professor of biobehavioral nursing sciences at the University of Florida in Gainesville.

Researchers are not clear on the causal relationship between vitamin D and a reduction in symptoms. Does D intake itself causes a reduction in symptoms in overweight people, or do overweight people with osteoarthritis who exercise outdoors and eat a broad diet produce more vitamin D? (Because sun exposure on skin enables the body to synthesize vitamin D, walking or being active outdoors is a good way to get adequate D.)

Whatever the precise relationship is, it’s always a good idea to strive for a healthy level of this necessary vitamin. The Institute of Medicine of the National Academies recommends that adults up to age 70 get 600 international units (IU) a day; for adults over 70 years, the recommended dietary allowance (RDA) is 800 IU. If your bloodwork shows a deficiency, here are three steps you can take:

  1. Eat vitamin D-rich foods. Make eggs and fatty fish (salmon, trout, and tuna are top choices) part of your regular diet, along with D-fortified foods such as milk and cereals.
  2. Supplement. Can’t or won’t eat foods rich in vitamin D? You can get your daily recommended daily dose in pill form.
  3. Let the sun shine in. More precisely, let it shine on you—at least a little bit. "You can synthesize an abundant supply of vitamin D with prudent sun exposure," Glover says. "Exposing your arms and legs to the sun during the day when the sunlight casts a shadow will make a good amount of vitamin D." Aim for no more than 15 to 30 minutes, and be careful not to go without sunscreen when the sun is high in the sky since it may cause you to burn.

Toni Glover, PhD, reviewed this article.


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