Comparative Analysis of Dietary Patterns in Children With Phenylketonuria Phenotypes and Controls: Implications for...

Individuals with phenylketonuria (PKU), caused by different variants of the phenylalanine hydroxylase gene, need to restrict their intake of phenylalanine. This study evaluated dietary patterns and physical activity levels in children with different PKU phenotypes compared to healthy controls. Eighty-two children were recruited (22 classic PKU [cPKU], 21 BH₄-responsive PKU, 19 hyperphenylalaninemia, and 20 controls). Anthropometric data, dietary intake, biochemical markers, and physical activity were assessed. Classic PKU (cPKU) subjects exhibited higher carbohydrate and sugar intake than other PKU phenotypes and controls. Notably, 42% of carbohydrate and 17% of sugar intake was from special low-protein foods, and 20% of carbohydrate and 29% of sugar intake was from protein substitutes. Compared to controls, the cPKU group was less physically active and reported a higher frequency of sweet consumption. Ninety percent of PKU had good metabolic control and carbohydrate intake was significantly correlated with HOMA-IR; however, after adjusting for age, only a trend remained (p = 0.08). Participants in the PKU group following a low natural protein diet consumed more carbohydrate and sugars than those on a normal-protein diet. Multivariate regression analysis showed that the low natural protein diet group was significantly associated with higher levels of vitamin B₁₂, linoleic acid, α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid, and with lower levels of total cholesterol and HDL-C compared to the normal-protein diet group. In conclusion, children with PKU, particularly those with classical PKU following low-protein diets, showed higher carbohydrate intake and distinct micronutrient and lipid profiles compared with healthy controls.