ABSTRACT
Vitamins were thought to be amines and hence the term ‘vitamines’ was coined for substances that are essential for life but needed in only minute amounts. Trace elements are inorganic compounds that, like vitamins, are essential for health and needed only in small amounts, known as the reference nutrient intake. Testing for vitamin and trace element deficiency should be carried out as soon as the diagnosis is suspected; the results of laboratory tests usually revert rapidly to normal once the patient has resumed eating a normal diet. Some vitamins are toxic if taken in excess, and overdosage has recently become more common, possibly because of the increased availability of these compounds in over-the-counter preparations. Hepatic stores of vitamin A are large and therefore clinical signs develop only after many months, or even years, of dietary deficiency. The common causes of vitamin E deficiency are poor intake and fat malabsorption. The plasma zinc-carrying protein metallothionine may also prove useful.
