Trace elements in clinical nutrition.

Although the nearly 20 essential trace elements in humans constitute a small fraction of total body weight (less than 4%), the effect of their presence on well-being is enormous. Enteral nutrition, whether oral or by tube, is fraught with problems that influence nutrient absorption, distribution, metabolism, and ultimately, excretion. Parenteral nutrition, although delivered to the intravascular milieu, carries with it no guarantee that the trace mineral will indeed reach the target site for action. With the questionable nature of dietary histories and their unavailability in the setting of relatively emergent nutrition therapy, it behooves the clinician to begin complete nutrition and to include recommended trace elements early on. The clinician must also be ever vigilant about delivering sufficient full-strength commercially available enteral formula to provide the recommended dietary allowances of trace minerals.