The importance of trace element speciation in nutritional sciences

The importance of trace element speciation in relation to absorption and metabolism is reviewed. Availability fur absorption depends upon the chemical form that is presented to the intestinal mucosal cells, namely solubility, oxidation state and the binding strength of ligands in the lumen of the gastrointestinal tract. For some elements, such as selenium, retention and utilisation appear to depend upon chemical form. The need to take speciation into consideration when undertaking trace element bioavailability studies employing isotopic labels: is discussed.