Free consumption of vegetables and fruits in nutritional management of adolescent patients with classical phenylketonuria

Background: We hypothesize that unrestricted consumption of vegetables and fruits in the treatment of adolescents with Classical Phenylketonuria will prevent patients from being non-compliant to their diet and support patients to succeed in their treatment. It is also anticipated that it will ease their daily life, provide against vitamin and mineral deficiencies and support them psychologically. Method: Adolescents with classical phenylketonuria (n=28) have been randomly assigned to Group 1 (n=14) and Group 2 (n=14). In the nutritional treatment, vegetables and fruits have been given according to their phenylalanine content for 14 days each, either in portions (Classic Period) and/or unrestricted (Free Period, <100 mg phenylalanine/100 g) in cross-over setting. Daily phenylalanine measurement in dried blood and three-day food consumption records (FCR) have been taken throughout the study. Results: In Group 1, phenylalanine level increased significantly after transiting from Classic Period to Free Period (p=0,013), whereas there was no difference in all subjects in Group 2 (p=0,203 and p=0,327 respectively), after classification of Non-Compliant Group (n=8) and Compliant Group (n=20), according to their treatment compliance for the last one year (%70); phenylalanine levels were significantly high in the Non-Compliant Group (p=0,002) in the Free Period, and there was no significant difference in the Compliant Group (p=0,295). FCR of the Non-Compliant Group showed significantly lower intake of phenylalanine from all foods in Classic Period (p=0,015), significantly lower energy (calorie) intake in Free Period (p=0,033) and significantly higher protein proportion in daily energy (calorie) in both periods (p=0,042 ve p=0,02 respectively); compared to Compliant Group. Conclusion: Free consumption of vegetables and fruits in the nutritional management of classical phenylketonuria in adolescents, does not cause an increase in the blood phenylalanine level of patients and does not effect the prognosis negatively. In the Non-Compliant Group, it doesn't decrease the blood phenylalanine level to normal range and doesn't improve compliance.