Vitamin D nutrient intake for all life stages.

摘要

Vitamin D, unlike other nutrients, is a conditionally required nutrient being obtained from two sources - predominantly by skin production upon exposure to natural ultraviolet (UV) solar radiation, and to a lesser extent by oral intake. Being a fat soluble vitamin it has a long half-life of about two weeks and is stored in fat tissues.1 For nearly six months of the year from October to March in Ireland, skin production is absent and the population is dependent on oral intake from natural foodstuffs, (which are consumed in small quantities only), fortified foodstuffs (most notably some milk products for the past 25 years) and vitamin D supplements, either in multivitamin tablets or in combination with calcium tablets,