Vitamin D is essential to bone health and there is growing evidence of its important contribution to our health beyond the skeletal system. This article briefly revises vitamin D metabolism, examines the needs of mother and baby and considers the contribution of vitamin D to child bone health.
What is vitamin D?
Vitamin D is a sterol, which has a hormone like activity. As vitamin D can be synthesised through the skin, vitamin D is not a 'true' vitamin (Box 1).
The main source of vitamin D is the sun, although the wavelength required for vitamin D synthesis is not available in Britain from the end of October until April. Dietary sources of vitamin D include salmon, mackerel and other oily fish, eggs and fortified foods such as margarine and breakfast cereals.1 However, less than
10 per cent of our vitamin D requirement is met through foods.2
When continually exposed to sunlight the vitamin D in skin begins to deteriorate, making it impossible to suffer vitamin D toxicity from exposure to sunlight. However, excess supplemental vitamin D could lead to toxicity.1 This causes an increase in blood calcium and symptoms including nausea, vomiting and weakness.
There are many modern day obstacles to obtaining sufficient vitamin D from the sun, such as sunscreen, clothing, being regularly indoors and skin pigmentation.3 Parents are advised to keep babies and children out of direct sunlight.