The sunshine supplement

hough vitamin D can be obtained in small quantities through our diet (from oily fish, red meat, egg yolk, mushrooms, fortified breakfast cereals and non-dairy milks), it’s estimated that only ten per cent of our RDA comes from food. In fact, as the British Dietetic Association emphasises in its guidelines, ‘Even a healthy, well-balanced diet that provides all the other vitamins and goodness you need, is unlikely to provide enough vitamin D.’ As sunshine remains our primary source, the much-misunderstood vitamin D is not strictly a vitamin (i.e. a necessary dietary factor), but a hormone. Unlike other vitamins, it’s synthesised by the skin, metabolised by the liver, and finally activated by the kidneys – a team effort!