Latest Lungs News
By Brenda Goodman
WebMD Health News
Reviewed by Laura J. Martin, MD
May 16, 2011 -- A small study that tested vitamin D against a placebo in patients with chronic lung disease found that those getting the vitamin D could breathe better and exercise more than those on the dummy pills.
Half were randomly assigned to get a high-dose vitamin D supplement; the other half got a dummy pill on the same schedule.
At the end of the study, those getting 100,000 international units (IU) of vitamin D each month had improvement in respiratory muscle strength and could exercise longer and more intensely than those who were not getting vitamin D.
"I think it's important," says study researcher Miek Hornikx, physiotherapist and doctoral student in the department of pneumology at the Katholieke Universiteit Leuven in Leuven, Belgium. "But more studies are needed, mainly to look at the mechanisms by which vitamin D can improve muscular function."
The study was presented at the 2011 American Thoracic Society International Conference in Denver.
Vitamin D and the Lungs
Studies show that people with COPD often have low levels of vitamin D, a vitamin best known for its role in keeping bones strong.
A 2010 report in the journal Thorax, for example, found that 60% of patients with severe COPD and 77% with very severe COPD had blood levels of vitamin D under 20 ng/mL, a level experts say is insufficient.
Some of the cause may be inherited. Certain gene variants have been shown to increase the risk of having low vitamin D levels.
But many experts think people with COPD may have low levels of vitamin D simply because they get less sun.
The body uses UV rays from sunlight to manufacture vitamin D.
"Getting outside is hard if you're sick," says Kevin K. Brown, MD, vice chairman of the department of medicine at National Jewish Health in Denver.
Vitamin D's benefits may extend well beyond bone health. It has also been shown to play a role in muscle health. Low levels have been shown, for example, to be associated with an increased risk of falls in men and slower walking speeds and poorer balanced in women.
"Since vitamin D is often depleted in patients with COPD, we wanted to see if vitamin D supplementation would have a beneficial effect on rehabilitation among these patients, perhaps by increasing muscle strength," Hornikx says.
Testing Supplements in COPD
All the patients participated in a three-month pulmonary rehabilitation program. Half were randomly selected to receive once-monthly, high-dose vitamin D supplements; the other half were given a placebo pill.
At the beginning of the study, and again at the end, researchers tested muscle strength in the lungs and the legs, vitamin D levels, and exercise capacity, which is a measure of how long and how intensely a person can exercise. Researchers also asked about improvements in quality of life before and after the study.
By the end of the study, study participants taking vitamin D had significantly greater improvements in exercise capacity and respiratory muscle strength than those taking the placebo.
Despite the fact that they could move and breathe better, however, study participants taking vitamin D didn't report any improvements in quality of life. Researchers think that may be because the study was relatively short.
Will Doctors Put COPD Patients on Vitamin D?
While it is still early, Brown says that based on the evidence he's seen, he's tempted to start testing his patients for vitamin D.
"I'm not fully convinced of this issue yet," he tells WebMD. "But I think the totality of this information is really pushing us toward testing many patients, and if found to be deficient, trying to think about ways to replace them."
Whether a person needs extra vitamin D will probably depend on the climate they live in, how much they're outdoors, and how much of the vitamin they get from their diet.
The U.S. recommended daily allowance of vitamin D is 600 IU daily for adults up to age 70 and 800 IU daily for adults over 70.