Vitamin D supplements Offer Limited Benefit in Asthma Treatment

In adults with persistent asthma and low levels of Vitamin D, intake of vitamin D3 supplements did not reduce treatment failure rate or symptoms, a new study reveals.

Low levels of vitamin D indicate serious health problems. They can cause asthma, diabetes, osteoporosis and many more health issues.  A new randomized control test conducted by researchers at Washington University School of Medicine in St. Louis found that adding vitamin D supplements for asthma treatment helps only those who achieve the required levels of supplement in the blood.  But the overall ability to control asthma does not improve.

"Previous studies suggested that if you have asthma and low levels of vitamin D in the blood, you have worse lung function, more asthma attacks and more emergency room visits than asthma patients with higher vitamin D levels," said Mario Castro, MD, the Alan A. and Edith L. Wolff Professor of Pulmonary and Critical Care Medicine. "This is the first randomized controlled trial to investigate whether taking vitamin D supplements can improve asthma control."

In the current study, researchers observed 408 adults at 9 medical centers. They all were diagnosed with mild - moderate asthma and also had deficient blood levels of vitamin D with an average of 18 nanograms per milliliter of blood.  Those having a count below 30 were considered abnormal.  As a part of the study the researchers made the subjects inhale a steroid daily to control asthma and rescue inhalers were kept ready in the event of an asthma attack.

The subjects were then randomly divided into two groups.  The treatment group got a dose of 100,000 international units of vitamin D3 followed by a daily dose of 4,000 units. The placebo group got similar inactive pills.

Both the groups did not show any difference in asthma control. No difference in treatment failure was also seen requiring the subjects to take more medication. There was no difference in asthma attacks and no difference in emergency care. Based on questionnaires it was seen that the subjects taking vitamin D did no experience an improvement in quality of life.

The groups, however, remained successful at reducing their daily dosage of inhaled steroids. 

"The difference was small - 15 micrograms of steroid per day - but statistically significant," said Castro, who treats patients at Barnes-Jewish Hospital. "Over the long term, even that small amount may have an important impact on reducing side effects of inhaled steroids. Although inhaled steroids work very well in controlling asthma, patients don't like them because they cause weight gain and increase the risk of diabetes and high blood pressure. Anything we can do to reduce the amount they need is important."

Compared to the control group, the treatment group showed improvement in asthma control and had 40 percent lesser treatment failure that needed more medication and half the number of asthma attacks.

"We're encouraged by this result, but we have to be careful," Castro said. "Our study was designed to look at the entire group that received vitamin D supplements, not just those who achieved higher levels of vitamin D in the blood. We need more studies looking at this question. But I am paying attention to vitamin D levels in my patients."

The finding appears in JAMA.