Currently, various formulas with different fatty acid compositions are used for enteral nutrition (EN). All formulas contain various concentrations of essential fatty acids: linoleic acid (LA) and alpha-linolenic acid (ALA); LA is biotransformed into arachidonic acid (AA) and ALA into eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in vivo. Some formulas contain preformed EPA and DHA.

However, the effects of the differences in the fatty acid composition on the fatty acid status of patients receiving long-term EN is not clear. We measured serum fatty acid concentrations in 50 patients with neurological diseases receiving long-term EN. The data were then compared retrospectively with reference to the fatty acid compositions of the formulas used. All of the patients received almost their entire nutritional intake via EN for at least 1 year. Blood samples were obtained just before injecting the EN solution.

Among the formulas that did not include EPA or DHA, formulas with low ALA concentrations were associated with low serum EPA and DHA. Conversely, the ALA-enriched formulas with reduced LA concentrations significantly increased EPA and DHA levels, although the levels remained lower than the control values. With the formula containing EPA and DHA, the EPA and DHA levels reached control values.

Therefore, the fatty acid composition of the EN formulas affected the fatty acid status of patients receiving long-term EN. Formulas containing preformed EPA and DHA with suitable amounts of essential fatty acids may benefit these patients.