The role of minerals and trace elements in relation to long-term health and chronic disease.

By definition, all of the major minerals and essential trace elements are necessary for health, and the range of these elements implies that they are part of all aspects of cellular function. They are involved as structural components, such as calcium or phosphorus in bone, as cofactors for enzyme activity or as an integral part of enzyme or protein structure (metalloproteins). They influence all metabolic pathways, are part of the antioxidant systems to prevent oxidative damage to cells, and are part of control mechanisms in the cell such as the zinc finger transcription factors. The breadth of this topic is extremely wide, and hence the current discussion will be limited only to nutritional deficiency states and their effects, and to examples selected from three key minerals (calcium, phosphorus, and magnesium), and from the well-established trace elements (iron, zinc, copper, selenium, chromium, molybdenum, manganese, cobalt and iodine). The ‘classical’ way of describing the progressive development of a nutritional deficiency state is shown in figure 1. When dietary supply is inadequate, the body will first mobilize any stores, if available, e.g. calcium will be mobilized from bone. Thereafter there will be an attempt to compensate either by increasing absorption from the gut, e.g. for iron, or reducing urinary excretion, e.g. for magnesium or phosphate. If the inadequate supply continues, or if there is no effective homeostatic mechanism, cellular deficiencies will occur which will have a wide range of effects on metabolism, depending on the element and the tissues mainly involved. These cellular effects may be apparent in some change in metabolism, e.g. chromium deficiency and glucose intolerance in type-2 diabetes, or magnesium deficiency and hypocalcemia. Signs and symptoms may be fairly nonspecific at this time – fatigue, mental and cognition changes, Allison SP, Go VLW (eds): Metabolic Issues of Clinical Nutrition. Nestlé Nutrition Workshop Series Clinical & Performance Program, vol 9, pp 169–185, Nestec Ltd., Vevey/S. Karger AG, Basel, © 2004.