Fish oils in parenteral nutrition: Why could these be important for gastrointestinal oncology?

By the time a gastroenterology patient is moved to parenteral nutrition, he or she is usually in poor health. All parenteral nutrition formulae contain essential nutrients, avoiding components that could cause an adverse reaction. The lipid component is often provided by a soy extract, containing all the fatty acids considered to be essential in the diet. Several trials have considered parenteral nutrition formulas with added fish oils, high in the long chain omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Given the range of biological functions associated with such compounds, especially in reducing inflammatory symptoms, this move would appear rational. However, while data from such trials are often positive, there has been variability among results. Some of this variability could be caused by environmental contaminants in the fish, and/or oxidation of the lipids because of poor storage. The situation is complicated by a recent report that fish oils may counter the effects of platinum chemotherapy. However, this effect associated with a minor component, hexadeca-4,7,10,13-tetraenoic acid. It is suggested that pure DHA and EPA would be beneficial additions to parenteral nutrition, reducing the probability of carcinogenesis and enhancing rational disease management. However, the jury is still out on fish oils more generally.