Could vitamin D reduce your risk of respiratory problems? Here's what the research has to say.

Vitamin D's bone-building benefits are well documented. Some research has also suggested that the vitamin plays a critical role in immunity and respiratory health, while other research disputes that. Here's what the latest studies say about vitamin D's effect on some common conditions.

Asthma

Studies have suggested that vitamin D deficiency may aggravate asthma symptoms in adults and that supplementation might help reduce them. Recent research evaluated 408 adults with asthma; 66 percent were vitamin D deficient. Half of the group received vitamin D3 tablets for 28 weeks. The remaining participants took a placebo during that same period. In addition, all patients used the inhaled corticosteroid ciclesonide to control their asthma.

Ultimately, there was no difference in the time to first treatment failure—defined as a decline in lung function, an increased need for asthma medications, or an asthma-related hospital visit—between the two groups. The investigators did report one small benefit: Vitamin D users needed slightly less ciclesonide to achieve symptom control, but the difference was not significant.

COPD

Studies suggest that low levels of vitamin D are common in people with chronic obstructive respiratory disease (COPD). However, a 2014 study found no association between vitamin D levels and exacerbations in people with moderate to severe COPD.

The investigators followed 356 study participants for two years. All had moderate to severe COPD, 30 percent had a vitamin D deficiency and 63 percent had inadequate levels of the vitamin (20 to less than 30 ng/dL). Although most of the participants experienced at least one exacerbation during the study, there was no relationship between vitamin D levels and the frequency or severity of exacerbation.

Upper Respiratory Infections

Vitamin D has major effects on nearly all cells of the immune system, so it's logical to wonder whether it might help prevent colds or other upper respiratory tract infections. Although some studies have shown evidence of a benefit, recent findings have been disappointing.

In 2014 a study recruited 2,259 generally healthy adults ages 45 to 75 to take either 1,000 IU of vitamin D, 1,200 mg of calcium, vitamin D plus calcium, or a placebo daily for four years. After one year, participants were asked to record any cold symptoms in a daily diary. Those who took vitamin D had roughly the same number of upper respiratory infections as those who took the placebo.The duration of the colds and the severity of the symptoms were similar as well.

The Bottom Line

Larger studies that have longer follow‑up and that try to answer different questions may shed more light on the role of vitamin D and respiratory health. For now, even though vitamin D supplementation has not been deemed beneficial for lung health, all adults still need to be sure they're getting enough.

Vitamin D's bone-building effects are particularly important for people with COPD; that's because osteoporosis-linked bone fractures are a well-known risk. And new evidence suggests vitamin D deficiency may be associated with muscle weakness in people who have COPD.

What's adequate? Opinions vary. The Institute of Medicine recommends 200 IU per day for healthy adults age 50 or younger, 400 IU for those ages 51 to 70 and 600 IU for people age 71 or older. But many people, especially older adults, need more to ensure that they have sufficient levels.

If you're not sure your vitamin D level is in a healthy range, ask your doctor to check it with a simple blood test.

From our sister publication REMEDY's Healthy Living (Summer 2015)

Publication Review By: the Editorial Staff at Healthcommunities.com

Published: 17 May 2015

Last Modified: 28 May 2015