Vitamin D Supplement Improves Asthma Control In Adults With Deficiency

Adults with asthma who also have vitamin D deficiency may achieve better asthma control when they take 25-hydroxycholecalciferol supplements, a clinical trial suggests.

The trial included 112 adults with asthma and serum 25-hydroxyvitamin-D3 levels below 30 ng/mL who were randomized to receive either oral supplements with 16,000 IU of calcifediol (25-hydroxycholecalciferol) per week or a placebo in addition to usual asthma treatment. The primary endpoint was scores on the asthma control test (ACT), which range from as low as 5 points for low control to as high as 25 points for excellent control.

At baseline, mean ACT scores were 17.71 in the intervention group and 19.02 in the control group. After six months, mean ACT scores were 20.49 in the intervention group and 18.23 in the control group, a statistically significant clinical difference of 3.66 points.

"The message that clinicians should take home is that patients should have serum vitamin D measured and, if they have a vitamin deficiency, vitamin D should be supplemented," said lead study author Dr. Ruben Andujar-Espinosa of the pulmonary department at Virgen de la Arrixaca University Clinical Hospital in Murcia, Spain.

"It could (result in) a decrease in inflammation and the best response to treatment with inhaled corticosteroids in these patients and, therefore, improve asthma control," Dr. Andujar-Espinosa said by email.

At baseline, participants' mean age was 55 years, and 87 (78%) were women. Baseline serum 25-hydroxyvitamin-D levels were 16.71 ng/mL in the treatment group and 17.48 ng/mL in the control group.

One secondary endpoint was the proportion of participants who achieved serum 25-hydroxyvitamin-D levels above 30 ng/mL. At six months, all but seven people in the intervention group (13%) met this endpoint, but only two patients (4%) in the control group achieved it.

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Another secondary endpoint was quality of life using the self-administered Mini Asthma Quality of Life Questionnaire (MAQLQ), which has 15 questions scored from 1 for "always" or "worst" symptoms to 7 for "never" or "best" quality of life. The mean difference between baseline and final scores was a 1.05-point increase in the intervention group, which is considered "moderately significant," compared with a decrease of 0.09 points in the control group.

There was no significant difference in usage of inhaled corticosteroids between the intervention and control groups at the end of the study, however.

No serious adverse events occurred, and there were no cases of hypercalcemia, renal colic or death. The most common side effect was gastrointestinal problems, experienced by two people on placebo and three participants receiving vitamin D supplements.

One limitation of the study is that it was too brief for researchers to examine whether continued supplementation might allow patients to reduce inhaled corticosteroid usage or for researchers to assess whether seasonal variation in asthma symptoms might impact the results, the study team notes in Thorax.

And, because the findings come from a relatively small study in a single center, they are unlikely to change clinical practice, said Dr. Adrian Martineau, a professor of respiratory infection and immunity at Queen Mary University of London in the UK.

"However, I suspect they will prompt larger, multi-center trials to determine whether these early promising findings can be replicated," Dr. Martineau, who wasn't involved in the study, said by email.

—Lisa Rapaport

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