Fish oil supplements and PKU

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For patients with phenylketonuria (PKU), dietary treatment requires a limited natural protein intake and, therefore, a low intake of long-chain omega-3 polyunsaturated fatty acids (LC-PUFA). Despite the restricted phenylalanine intake, patients with PKU have demonstrable neurological deficits and may have impaired specific motor function. The mechanisms behind these less than perfect outcomes may, in part, be related to fluctuations in plasma phenylalanine levels. However, an unintended consequence of the diet may be to induce metabolic imbalance, specifically LC-PUFA deficiencies. Indeed, there is a wealth of recent data indicating the important role for LC-PUFA in neurological development and function.

In this issue of The Journal, Beblo et al report that supplementation of the “PKU diet” with fish oil (a rich source of LC-PUFA) normalized plasma levels of phospholipids (LC-PUFA) and improved motor skills. These results should stimulate further thought regarding the optimal nutrient intakes in children with PKU.