Vitamin D supplements can reduce COPD exacerbations by over 40% in patients with a vitamin D deficiency, according to new research from Queen Mary University of London.

The NIHR-funded randomised trial, published in the journal Lancet Respiratory Medicine, included 240 patients with COPD in and around London. Half of the patients (122) received vitamin D supplements (6 x 2-monthly oral doses of 3mg) and the other half (118) received an equivalent placebo. The risk, severity and duration of flare-ups was then compared between the two groups.

Patients with a vitamin D deficiency benefited dramatically from taking the supplements but the striking reduction in flare-ups was not seen among patients who had a higher vitamin D status at the start of the trial.

However, researchers did find vitamin D supplementation modestly reduced the severity and duration of flare-up symptoms in all patients in the vitamin D group, regardless of their baseline vitamin D levels, compared to the placebo group.

This is the first clinical trial to investigate the impact of vitamin D supplementation on severity and duration of COPD symptoms. One previous trial has linked vitamin D to a reduction in COPD disease flare ups but this was limited to patients with very severe conditions. This trial is larger and studied patients with a much broader spectrum of diseases, ranging from mild to severe.