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News Article

Do vitamin D supplements reduce risk of acute respiratory infections?

Systematic review shows vitamin D deficient patients might benefit.

Vitamin D may help prevent acute respiratory infections (ARIs) like flu, colds and pneumonia suggested a systematic review in the BMJ last week. It’s a bit early to change practice for the general population however, cautions the editorial that accompanies it. The editorial sheds some doubt on clinical relevance of the systematic review findings and some of the methodology. The results for vitamin D deficient patients were strongest and both articles emphasise the need for more trials to confirm that.

Acute respiratory infections are a major cause of death globally accounting for up to a third of deaths. Observational studies suggest a link between vitamin D deficiency and respiratory infection and these have led to a series of randomised controlled trials (RCTs) with vitamin D supplements. Martineau and colleagues have published several studies on vitamin D and respiratory diseases including a systematic review in 2013 that found RCTs of vitamin D for ARIs gave conflicting results. Most of the attempts to conduct meta-analyses on the data so have not given a clear result.

In this systematic review, Martineau and colleagues used a new method of analysis called individual patient data meta-analysis and they have included more studies in an attempt to get to a clear result. The systematic review analysed 25 trials with a total of 11,321 participants aged 0-95 years with a variety of respiratory tract infections from pneumonia to otitis media. They received varying doses of vitamin D.

The meta-analysis suggests that vitamin D is effective at reducing respiratory infections as it reduced the proportion of patients getting an infection by 12%. The authors calculate that 33 people would need to take vitamin D supplements to prevent one acute respiratory tract infection. Further analyses among specific groups showed the benefit was greater in those receiving daily or weekly vitamin D without additional large doses. The protective effects in that group were strongest in those with severe vitamin D deficiency (less than 25 nmol/L baseline blood levels), although this group was quite small.

The accompanying editorial to this review is sceptical. It points out that the effects of the supplement may not be clinically relevant because the vitamin D supplement only reduced the proportion of patients suffering an infection from 42% to 40%. That slight decrease isn’t enough to justify taking a supplement, it says. The authors have a few comments on the methodology as well, questioning whether the studies analysed are too disparate to give a meaningful clinical answer and asking why the criteria for exclusion of studies are not given

The editorial suggests that there seems to be a benefit in small children that’s worth another look. The study authors and editorial authors both agree that RCTs in the future should be studying vitamin D deficient patients. Unfortunately those in progress do not do so, so are unlikely to solve the issue.

Bolland and Avenell the authors of the editorial have co-authored several papers about vitamin D and bone disorders including a recent one in the BMJ that concluded vitamin D was not recommended for anything other than musculoskeletal disorders.

Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. Adrian Martineau, David A Jolliffe, , Richard L Hooper, Lauren Greenberg, John F Aloia, Peter Bergman, Gal Dubnov-Raz, Susanna Esposito, Davaasambuu Ganmaa, Adit A Ginde, Emma C Goodall, Cameron C Grant, Christopher J Griffiths, Wim Janssens, Ilkka Laaksi, Semira Manaseki-Holland, David Mauger, David R Murdoch, Rachel Neale, Judy R Rees, Steve Simpson Jr, Iwona Stelmach, Geeta Trilok Kumar, Mitsuyoshi Urashima, Carlos A Camargo Jr, BMJ 2017; 356 i6583.

Do vitamin D supplements help prevent respiratory tract infections? Mark J Bolland,and Alison Avenell. BMJ 2017; 356 :j456


Article details

  • Author(s)
  • I.Hoskins
  • Date
  • 21 February 2017
  • Source
  • BMJ
  • Subject(s)
  • Nutrition & disease