Inborn errors of metabolism with a protein‐restricted diet: Effect on polyunsaturated fatty acids

Previous studies have shown that phenylketonuric patients display a deficiency in long‐chain polyunsaturated fatty acids. A study has now been performed on 13 cases (5 with methylmalonic acidaemia and 8 with urea cycle disorders) whose dietary treatment also implies a limitation in protein‐rich food. Plasma and red‐cell phospholipid fatty acid profiles were studied. The most relevant results were a lower percentage of docosahexaenoic acid in plasma and red‐cell phospholipids (0.91% ± 0.53% vs 2.88% ± 1.17% and 2.07% ± 0.92% vs 3.62% ± 1.01% (p < 0.001)) and a lower percentage of arachidonic acid in plasma (5.22% ± 2.02% vs 8.3% ± 2.11% (p < 0.001)). A long‐chain polyunsaturated acid deficiency has also been confirmed in this group of metabolic patients and a dietary supplement is recommended since this population is subject to a special risk factor with regard to adequate psychomotor development. By extrapolating these data to the general population, the possibility can be inferred that long‐chain polyunsaturated fatty acids are semi‐essential in infant nutrition far beyond the breast‐feeding period.