Vitamin gets D for colds prevention

A Canadian study set out to find whether supplementing with high-dose vitamin D helped prevent children catching colds… and found it didn’t

Previous studies have suggested that children may be more likely to catch colds if they have low levels of serum 25-hydroxyvitamin D.

Canadian researchers set out to find out whether daily high-dose administration of vitamin D reduced overall wintertime upper respiratory tract infections.

The study, published in JAMA, saw Dr Jonathon L. Maguire of the University of Toronto, and colleagues randomly assign children aged one through five years to receive 2,000 IU/d of vitamin D oral supplementation (high-dose group; n=349) or 400 IU/d (standard-dose group; n=354) for a minimum of four months between September and May.

The average number of laboratory-confirmed (based on parent-collected nasal swabs) upper respiratory tract infections per child were 1.05 for the high-dose group and 1.03 for the standard-dose group.

There was also no significant difference in the median time to the first laboratory-confirmed infection: 3.95 months for the high-dose group vs 3.29 months for the standard-dose group, or number of parent-reported upper respiratory tract illnesses between groups (625 for high-dose vs 600 for standard-dose groups).

“These findings do not support the routine use of high-dose vitamin D supplementation in children for the prevention of viral upper respiratory tract infections,” the authors write.

A limitation of the study was that children may have had upper respiratory tract infections without swabs being submitted.

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  1. Debbie Rigby

    The conclusion from the study was “Vitamin D dosing higher than 400 IU/d may not be indicated for
    preventing wintertime viral upper respiratory tract infections in

    2000IU was no more effective than 400IU, but doesn’t mean vitamin D supplementation was not effective. There was no placebo arm, so can’t conclude anything about efficacy.

    Epidemiological studies support a link between low
    25-hydroxyvitamin D levels and a higher risk of viral upper respiratory
    tract infections.

    • Debbie Rigby

      Also baseline 25(OH)D levels were pretty good and would be classed as sufficient by our accepted levels ie 92nmol/L in high-dose group and 90 in low-dose group. About one-third had baseline levels below 75nmol/L. Supplementation over summer months increased levels to 121.5 vs 91.9nmol/L.

      I don’t think this study adds much to the body of evidence – for or against supplementation.

  2. Peter Allen

    I’m getting the feeling that some people carry a prejudice against vitamin-D having any beneficial effects.
    ‘Vitamin gets D’ is to me such an attitude — though I’m sure you would deny it.
    Then there was the meta study, positive. NEW VITAMIN D INDICATION SUGGESTED – AND CHALLENGED as if a challenge bears equal weight.
    My feeling is that the only valid trials compare two groups: normal D vs deficiency, each group long term.
    Most trials involve short-term top-ups of deficiency, call them ‘normal.

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