Nutritional Counseling Promotes Adherence to the Mediterranean Diet and Healthy Eating in Italian Patients Affected by Phenylketonuria and Treated with Pegvaliase

Background/objectives: Pegvaliase, a subcutaneous therapy to treat phenylketonuria (PKU), has allowed these patients to maintain adequate phenylalanine (Phe) blood values without following a Phe-controlled diet; this brings up the challenge of promoting healthy eating while moving away from prescription diets. In our center, every patient treated with Pegvaliase undergoes routine nutritional counseling aimed at promoting adherence to the Mediterranean diet (MedDiet) during regular inpatient visits. This study aims to assess adherence to MedDiet and the adequacy of the diets of patients treated with Pegvaliase regarding micro- and macronutrients.

Methods: Seven patients on chronic therapy with Pegvaliase underwent a dietetic evaluation to assess the composition of their diets in terms of micro- and macronutrients; they were also administered the Mediterranean Diet Score (MDS) questionnaire. Subcategories from MDS were extracted to evaluate the consumption of foods typically included (vegetables, olive oil, etc.) and typically excluded (red meat, etc.) in the MedDiet. To assess the adequacy of the diet, nutrient and energy levels were compared with guidelines for the Italian population.

Results: MedDiet adherence in our sample was comparable to the general population; in terms of macronutrients, good adherence to the recommendations was observed, with every one of them met except for excessive simple sugar consumption. Micronutrient dietary intake was inadequate for zinc, iron, selenium, folate, thiamine, and riboflavin.

Conclusions: While more work is necessary to help patients treated with Pegvaliase to progress toward healthy eating, our study suggests that nutritional counseling routinely performed during inpatient visits, typically twice a year, effectively promotes healthier eating habits than those observed in the general population.