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Vitamin D supplements halve the number of exacerbations of chronic obstructive pulmonary disease (COPD) in people with low levels of the vitamin, from two per year to one per year. The supplements do not affect exacerbations of COPD in people who are not deficient.

This NIHR-funded review is the first to pool individual-level data from randomly controlled trials to see whether taking vitamin D can help reduce exacerbations.

People with moderate to severe COPD may be at risk of low vitamin D levels because their illness reduces their opportunities to get out into the sunlight.

These findings suggest that vitamin D is an effective, safe prevention for those with COPD found to be deficient.

Why was this study needed?

Chronic obstructive pulmonary disease (COPD) is one of the top two reasons for UK emergency hospital admission. The condition costs the NHS approximately £1.9 billion annually. It causes 30,000 deaths every year in England.

Vitamin D plays a key role in regulating the body’s calcium levels and is essential for healthy bones and muscles. It has recently been shown to reduce asthma symptoms and chest infections. The vitamin is made in the skin from exposure to sufficient sunlight and can also come from food. However, people with restricted time outdoors can have low levels.

This review aimed to find out whether vitamin D can reduce exacerbations of COPD and to study whether impacts differ according to patient characteristics.

What did this study do?

This systematic review analysed data from three of the four randomised controlled trials carried out to date. Participants in the UK, Belgium and the Netherlands were randomly assigned to receive oral vitamin D or a placebo alongside any COPD treatment. Trial authors were asked to provide full individual-level data sets, giving a combined dataset of 469 adults.

The trials included people with mild, moderate and severe COPD. Vitamin D doses were not combined with other supplements and ranged from 30 micrograms daily for six months to 2,500 micrograms monthly for one year.

All three trials had a low risk of bias and were double-blind, meaning that patients, clinicians and researchers did not know which treatment was given.

What did it find?

  • When pooling individual-level data for people with low vitamin D at the start of the trial (less than 25 nmol/L), those taking a vitamin D supplement experienced on average 1.2 moderate or severe exacerbations of COPD in a year (95% confidence interval [CI] 0.86 to 1.75), compared to 2.1 exacerbations in the placebo group (adjusted incidence rate ratio [aIRR] 0.55, 95% CI 0.36 to 0.84; 3 trials, 87 adults).
  • There was no significant effect of vitamin D supplementation for those with adequate baseline vitamin D levels (at least 25 nmol/L) (aIRR 1.04, 95% CI 0.85 to 1.27; 3 trials, 382 adults). 
  • When all those who had vitamin D supplementation were compared with all those who had a placebo, there was no difference in exacerbation rates (aIRR 0.94, 95% CI 0.78 to 1.13; 3 trials, 469 adults).
  • Vitamin D did not cause any increase in the proportion of participants experiencing a serious adverse event.

What does current guidance say on this issue?

Public Health England 2016 guidance advises that everyone needs 10 micrograms of vitamin D daily. In the spring and summer, sufficient can come from sunlight and dietary sources. In the autumn and winter, people should consider supplements.

A NICE 2014 guideline on vitamin D for specific population groups advises that vitamin D levels should be tested only when a person is at especially high risk of deficiency, or there is a clinical reason to do so. Prompts for health professionals to recommend supplements should be integrated into health and social care systems.

The NICE 2018 guideline for adults with COPD does not include advice on vitamin D. It states that pulmonary rehabilitation programmes should incorporate nutritional advice.

What are the implications?

Though the number of participants was small and the number of exacerbations relatively low, the results are in keeping with what is already known about vitamin D. That is it can reduce the risk of chest infections in the general population, especially for those with low levels.

The supplements are low cost, but testing for deficiency also has resource implications.  Health practitioners could integrate Public Health England advice into services for people with COPD based on this evidence. This would mean most people with COPD could consider taking supplements through the autumn and winter months.

Flu and pneumococcal vaccinations and pulmonary rehabilitation programmes provide a contact point with COPD patients and an opportunity for health practitioners to give advice on vitamin D intake.

Citation and Funding

Jolliffe D, Greenberg L, Hooper R et al. Vitamin D to prevent exacerbations of COPD: systematic review and meta-analysis of individual participant data from randomised controlled trials. Thorax. 2019; 10 January. doi: 10.1136/thoraxjnl-2018-212092. [Epub ahead of print].

This project was funded by the National Institute for Health Research Health Technology Appraisal programme (project number 13/03/25).



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NICE. Chronic obstructive pulmonary disease in over 16s: diagnosis and management. NG115. London: National Institute for Health and Care Excellence; 2018.

NICE. Vitamin D: supplement use in specific population groups. PH56. London: National Institute for Health and Care Excellence; 2014 (updated 2017).

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Martineau AR, Jolliffe DA, Hooper RL et al. Vitamin D supplementation to prevent acute respiratory tract infections: meta-analysis of individual participant data. BMJ. 2017;356:i6583.

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Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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