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Sixty seconds on . . . vitamin D

BMJ 2020; 371 doi: https://doi.org/10.1136/bmj.m3872 (Published 05 October 2020) Cite this as: BMJ 2020;371:m3872
  1. Zosia Kmietowicz
  1. The BMJ

The sunshine one?

Indeed, as we enter the season of mists and mellow fruitfulness, thoughts have been turning to the sunshine vitamin and its potential role in beating covid-19.

Can you shed more light on that?

Health secretary Matt Hancock put his foot in it when he told the House of Commons last week that he had ordered a trial to see if vitamin D reduced the incidence or effects of covid-19 and that “the results were that it does not appear to have any impact.” It turns out, there have been no government trials.

Did that rays some questions?

Hancock appears to have been confused. Rupa Huq, a Labour backbencher, put him right when she said that he had been referring to a review of evidence published in June by the National Institute for Health and Care Excellence.1 “The word ‘trial’ implies fresh evidence, not reheated leftovers,” she said.

It sounds like there was more heat than light. What did NICE say?

NICE’s summary, which looked specifically at emerging evidence on the role of vitamin D in relation to covid-19, concluded that there is currently no evidence to support supplements reducing the risk or severity of covid-19.2 The Scientific Advisory Commission on Nutrition also studied whether vitamin D supplementation could reduce the risk of acute respiratory tract infections other than covid-19, and concluded that the jury was still out.3

Any more bones you can throw me?

Adrian Martineau has updated his 2017 BMJ4 meta-analysis of vitamin D’s effects on respiratory tract infections, which is currently on a preprint server and not yet peer reviewed.5 He told The BMJ, “The antiviral and anti-inflammatory actions of vitamin D make it an interesting candidate for prevention of viral respiratory infections. Our updated meta-analysis shows modest protective effects overall. Clinical trials of vitamin D to reduce risk or severity of covid-19 are now needed.”

Aren’t we all supposed to be taking vitamin D anyway?

You’re right. In 2016 Public Health England advised children and adults to consider taking 10 µg of vitamin D a day in autumn and winter to protect bone and muscle health. In Scotland the government has similar advice for times when “10-15 minutes of unprotected Scottish sun exposure” is not possible.6

Footnotes

  • Correction: On 12 October we corrected the time span in the last sentence to 10-15 minutes (not 0-15 minutes).

References

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