Professor Rose Anne Kenny:

If I may respond to the question about vitamin D and chest infections or bacterial or viral infections, again, last week, with colleagues in the UK, we published a paper which looked at the evidence for this in the context of big bolus doses of vitamin D, which would be given infrequently, or taking daily supplementation. The evidence from all the studies that were pooled together - 42 randomised trials involving almost 48,000 subjects - clearly showed a significant reduction in acute chest infections, be they viral or bacterial, with regular, daily maintenance supplementation but not with intermittent high-dose boluses. This, we proposed, may be why there is confusion out there among academics about vitamin D. Giving bolus doses appears to have a different effect on the pathways involved in metabolising vitamin D from daily supplementation with it, but it does have a positive effect, if taken daily, on general bacterial and viral infections.