ABSTRACT
Vitamins and trace elements are micronutrients which are essential dietary components required for the maintenance of health. The dietary requirements for individual micronutrients vary and are subject to a number of different factors. A window of the amount to be ingested daily exists for each, and clinical disorders may arise from deficiency or excess. The most commonly used guideline values quoted for this are the recommended daily amounts (RDA) published regularly by the United States National Academy of Sciences Food and Nutrition Board (Table 24.1), the recommended nutritional intake (RNI) published by the Committee on Medical Aspects of Food and Nutrition Policy (COMA) in the UK, and the recommended daily intake (RDI) published by the World Health Organization. These values define amounts which are adequate to meet known nutrient needs of practically all healthy persons. It should be stressed, however, that this is adequate and may not be optimal in individual cases.
