Vitamin A is essential for normal growth and development. Deficiency leads to poor vision in dim light and eventually to blindness. Excess retinol can be toxic and may be particularly dangerous for the unborn child. It is for this reason that women who are pregnant, or who might become pregnant are advised not to take high-dose vitamin A supplements unless they are advised to do so by a health professional. Liver and liver products may contain a large amount of vitamin A, so these should also be avoided.
Retinol is found in liver, whole milk, cheese and butter.
Carotenes are found in milk, carrots, dark green leafy vegetables and orange coloured fruits, eg mango and apricots. Figure 1 illustrates the sources of vitamin A in the UK diet. The Dietary and Nutritional Survey of British Adults . Vitamin D is found in foods in two main forms, mostly as cholecalciferol and in small amounts as ergocalciferol . In this form it works as a hormone in controlling the amount of calcium absorbed by the intestine.