More of the "sunshine vitamin" may help older people preserve muscle strength.

A new study suggests that higher levels of vitamin D could result in improved physical function in the elderly not only by helping to keep bones strong, but also by helping to keep muscles strong.

Announcing their findings at the Experimental Biology 2010 meeting in Anaheim, Calif., the study’s researchers said more trials would be necessary to help determine what role vitamin D had in muscle health or if there had been other variables—such as exercise—involved in the results.

The scientists analyzed levels of 25-hydroxyvitamin D (the active circulating form) in participants’ blood samples and found that seniors with higher amounts of the circulating 25-hydroxyvitamin D were more likely to have larger muscles and greater physical function.

Although the researchers’ observations cannot prove a causal relationship between vitamin D and muscle strength, they do support widely held views that increased Recommended Dietary Intakes for vitamin D are needed to combat the effects of the aging process.

Recently, another study from McGill University also reported that higher vitamin D levels were also linked to reduced levels of accumulated fat in muscle tissue.

These recent studies add to a body of evidence from epidemiologic studies and clinical trials that current Recommended Dietary Intakes are largely inadequate for health in the long term and that higher vitamin D intake could result in an overall better quality of life.

The Institute of Medicine has already announced a 24-month review of vitamin D research to be performed by a committee, which will release a report by end of summer 2010. The committee is expected to recommend raising Recommended Dietary Intakes of vitamin D.

Getting enough D

Unlike in winter months, when across most of North America the sun’s UVB rays are not strong enough for producing sufficient vitamin D, the coming summer months present a different story.

Just going outside for about 20 minutes between 10 a.m. and 3 p.m. in the summer is generally enough for people to synthesize between 10,000 IU and 20,000 IU of vitamin D, an amount drastically higher than the 400 IU found in a typical glass of milk.

Despite the ease of obtaining vitamin D from sunlight, however, epidemiologic studies have found that among the elderly, many have insufficient levels for optimal health even in summer. The statistics may be the result a decline in vitamin D synthesis that comes with older age as well as too much time spent indoors.

For the elderly (and for anyone), the easiest and safest way to obtain  sufficient vitamin D is through supplementation. Supplementation with 1,000 or 2,000 IU daily is suggested to help obtain enough for supporting the health of bones, muscles and the heart.   

Seniors can also make sure they are obtaining sufficient vitamin D by requesting a vitamin D status test from their doctors or by ordering a home test from a non-profit organization such as Grassroots Health.