Professor Rose Anne Kenny:

On supplementation, the public health message and vitamin D flying off the shelves, the Health Research Board, HRB, funded a study where we looked at vitamin D supplementations during Covid. We also had data pre-Covid relating to people aged 50 years and above. The prevalence of supplementation for vitamin D pre-Covid was 9% and the majority were women. During Covid, it had increased by a further 14%. That looks like 23% coverage. I suspect it is higher now over the past number of weeks because there has been further publicity.

There is emerging data that taking large bolus doses, possibly even monthly, may not have the same beneficial effects as more regular supplementation. It is new data and needs more work. I personally would not be comfortable taking a bolus dose once a month instead of more frequent supplementation.