Effects of long-chain polyunsaturated fatty acid supplementation on fatty acid status and visual function in treated children with hyperphenylalaninemia

Background: Children with phenylalanine-hydroxylase deficiency (type- I hyp erphenylalaninemia, HPA) follow a low-phenylalanine diet, severely restrict ed in animal foods and long-chain polyunsaturated fatty acids (LCPUFA). Con sequently, they have a poor LCPUFA status, particularly for docosahexaenoic acid (DHA). DHA is relevant to visual and neural development. Objective: To investigate the effects of a 12-month supplementation with LC PUFA in a double-blind, placebo-controlled trial in treated children with H PA. Study design: Twenty children with well-controlled I-IPA were randomly allo cated to receive either a fat supplement (supplying 26% as fatty acids incl uding DHA, 8%) or a placebo. The fatty acid composition of erythrocyte lipi ds and the visual evoked potentials were measured at baseline and after 12 months of supplementation. Reference data were obtained from healthy childr en of comparable age. Results: At baseline children with HPA had a poorer DHA status and prolonge d P100 wave latencies than the reference group, lit the end of the trial th e LCPUFA group showed a significant increase in DI IA levels of erythrocyte lipids. In the LCPUFA group P100 wave latency decreased and was negatively associated with the DHA changes. Conclusions: A balanced dietary supplementation with LCPUFA in children wit h HPA is associated with an increase of the DI IA pool and improved visual function.