Dietary glycemic index, glycemic load and metabolic profile in children with phenylketonuria.

BACKGROUND AND AIMS: No data exist in the current literature on the glycemic index (GI) and glycemic load (GL) of the diet of phenylketonuric (PKU) children. The aims of this study were to examine the dietary GI and GL in PKU children on a low-phenylalanine (Phe)-diet and to evaluate whether an association may exist between the carbohydrate quality and the metabolic profile.

METHODS: Twenty-one PKU children (age 5-11 years) and 21 healthy children, gender and age matched, were enrolled. Dietary (including GI and GL) and blood biochemical assessments were performed.

RESULTS: No difference was observed for daily energy intake between PKU and healthy children. Compared to healthy controls, PKU children consumed less protein (p = 0.001) and fat (p = 0.028), and more carbohydrate (% of total energy, p = 0.004) and fiber (p = 0.009). PKU children had higher daily GI than healthy children (mean difference (95% confidence interval), 13.7 (9.3-18.3)) and higher GL (31.7 (10.1-53.2)). PKU children exhibited lower blood total and low density lipoprotein cholesterol (LDL) levels (p < 0.01) and higher triglyceride level (p = 0.014) than healthy children, while glucose and insulin concentrations did not differ. In PKU children the dietary GL was associated with triglyceride glucose index (Spearman's correlation coefficient = 0.515, p = 0.034).

CONCLUSION: In PKU children a relationship of the dietary treatment with GI and GL, blood triglycerides and triglyceride glucose index may exist. Improvement towards an optimal diet for PKU children could include additional attention to the management of dietary carbohydrate quality.