Micronutrient supplementation in adult nutrition therapy: practical considerations

Preexisting micronutrient (vitamins and trace elements) deficiencies are often present in hospitalized patients. Deficiencies occur due to inadequate or inappropriate administration, increased or altered requirements, and increased losses, affecting various biochemical processes and resulting in organ dysfunction, poor wound healing, and altered immune status with deleterious sequelae. Guidelines for the 13 essential vitamins and 10 essential trace elements have been established. These recommendations, however, are applicable to healthy adults and not to critically ill patients, in whom decreased serum levels may indicate actual deficiencies or a deficiency due to redistribution. Benefits of supplementation over and above the daily requirements, which may not result in increased serum levels, are also unclear and may, in fact, be detrimental. Vitamin requirements are increased in disease states, but a similar recommendation for trace elements has not been initiated except for selenium (Se) and zinc (Zn). In practice, a multivitamin preparation and a multiple trace element admixture (containing Zn, Se, copper, chromium, and manganese) are added to parenteral nutrition formulations. Most enteral nutrition preparations also contain adequate amounts of vitamins and trace elements, although bioavailability may be an issue. Detailed information about individual micronutrient use specifically in hospitalized adult patients receiving nutrition therapy will be discussed, emphasizing the practical and clinical aspects. Clinicians are encouraged to think of micronutrients not as nutritional supplements alone but also as therapeutic agents and nutraceuticals.