Professor James Bernard Walsh:

On the point about units, it is important to clarify that it is 800 to 1,000 units which is 20 to 25 mcg.

With regard to the level at which one is deficient, while technically a level of 30 nmol/l is considered deficient and a level 50 nmol/l is classified as sufficient, it is important that we look upon anything less than 50 nmol/l as insufficient. In that case, 70% of people among all age groups we are seeing in winter do not have sufficient vitamin D. This is the case across the entire Dublin metropolitan area. That is a simple figure. Professor Kenny's work with the Irish Longitudinal Study on Ageing, TILDA, shows a similar result for the whole of Ireland. That is what we are talking about. We should talk about sufficiency. At this point in time, only 30% of the Dublin population has sufficient vitamin D and it is no different for the rest of the country. This is the case across all age groups.