The use of n-3 PUFAs (fish oil) in enteral nutrition.

Severely ill patients in need of enteral nutrition support must obtain all essential nutrients in at least the amounts recommended for daily intake (RDA) by healthy populations. Until recently essential fatty acids have been entirely omitted from enteral solutions or included only in the form of n-6 PUFAs which are structurally important for cell membranes and play a significant role as precursors (esp. arachidonic acid, AA) of eicosanoids (prostaglandins, thromboxanes, leukotrienes). However, in the absence of n-3 PUFAs, these eicosanoids may produce exaggerated effects in acute stress responses causing immunosuppression, platelet aggregation and excessive or chronic inflammation. n-3 PUFAs act as precursors of complementary eicosanoids which counteract the exaggerated responses of AA-derived eicosanoids. Therefore, n-3 PUFAs should be part of any optimally balanced diet and must be included also in enteral solutions. Since the transformation of the n-3 parent fatty acid, alpha-linolenic acid, to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is slow and unreliable, it is necessary to provide them as preformed nutrients as they occur in fish oil. The British Nutrition Foundation recommends a daily intake of EPA and DHA in amounts corresponding to the intake of 3 to 4 g standardized fish oil. The requirements can also be covered by the weekly consumption of 2 to 3 portions of fatty fish. Preliminary clinical trials have shown certain beneficial effects of fish oil intakes in diseases associated with inflammatory reactions such as rheumatoid arthritis or inflammatory bowel disease, in conditions with impaired immune competence such as burns, post-operative situations and cyclosporine treatment after renal transplants, and in conditions with enhanced platelet aggregation such as after coronary angioplasty. While these findings must be verified in strictly controlled trials, the intake of fish oil n-3 PUFAs in a balanced ratio to n-6 PUFAs can be recommended for all patients including those in need of enteral nutrition support.