Interactions related to trace elements in parenteral nutrition.

Trace elements (TE) are now commonly added into the nutritive admixtures used in total parenteral nutrition (TPN) to prevent deficiencies which can be observed in patients undergoing long-term intravenous feeding. Although the needs in TE are not exactly known during a TPN, some of them must be considered as essential according to the results of studies dealing with general nutritional deficiencies. Among essential TE copper, iron and zinc are found at relatively high levels in organism. Chromium, manganese and selenium are also very important even though they are present at lower levels. In the case of a parenteral nutrition, the composition of the mixture is precisely defined and both digestion and absorption steps are shunted. Nevertheless, beneficial and/or negative physicochemical and metabolic interactions can occur between TE and the other nutrients. These interactions must be studied and taken into account because they can modify the bioavailability of the trace elements. In this article, our aim is to review the main recent bodies of knowledge which could be helpful to understand and prevent nutritional problems linked to these interactions during parenteral nutrition.