Trace Element and Micronutrient Reference Laboratory
Scotland's specialised laboratory for trace elements and vitamins in health and disease
Trace Elements - an Introduction (2)
Nutritional Deficiency States
Nutritional deficiency of vitamins and trace elements is relatively uncommon in developed countries. When it occurs it is usually due to poor diet (eg. alcohol-related), malabsorption, inadequate supplementation of total parenteral nutrition (TPN), inborn errors of metabolism, and food fads. Nutritional deficiency may be sub-clinical or masked by co-existing disease so making the measurement of blood levels of vitamins and trace elements potentially useful. However, assessing the adequacy of dietary intake of nutrients is complex and the bioavailability of trace elements may be reduced by the species present, and intraluminal interactions with other competing trace elements and dietary substances such as phytic acid and fibre. Disorders involving Fe, I, and Co can be investigated by established methods - haemoglobin, thyroid hormones and vitamin B12, and so their measurement is infrequently required.
Clinical interest in essential trace elements increased when reversible symptomatic deficiencies of Cr, Cu, Zn, Se, and Mo were described in patients receiving long-term total parenteral nutrition (TPN). Similarly, diets formulated for the management of inborn errors of metabolism such as phenylketonuria, have been associated with deficiencies of Se, Zn and other elements. In both cases, the use of highly purified nutrients has led to deficiency diseases never before clearly observed.
Young children, especially those in malnourished populations, are also at risk. Diets used in rehabilitation may not always supply sufficient vitamins and trace elements such as Zn, Cu and Se, and growth and recovery may therefore be compromised. The premature baby has a special requirement for micronutrients which is far from understood. Oral provision is complicated by immature gut function and can result in varying degrees of malabsorption.
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