Understanding the impact of feeding development, food acceptance and educational strategies in Phenylketonuria (PKU)

Morris (Evans), Sharon ORCID: 0000-0002-7654-3621 (2023). Understanding the impact of feeding development, food acceptance and educational strategies in Phenylketonuria (PKU). University of Birmingham. Ph.D.

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Abstract

Background: A phenylalanine restricted diet is the principal treatment in the inherited metabolic disorder phenylketonuria (PKU) but is practically difficult to apply in children. Feeding patterns and practices, growth and parental anxiety have not been reported in infants with PKU. There is limited information about dietary patterns, taste preferences, food acceptance and neophobia in children, impeded by inadequate tools to measure habitual food intake. Parents/caregivers have difficulty interpreting food labels, calculating protein intake and determining food suitability, compounded by conflicting advice from health professionals. Accurate, consistent, evidence based dietary information, and suitable educational tools are essential.

Methods: A series of longitudinal case-control studies report on growth, weaning age, feeding progression, the feeding environment, mealtime emotions and behaviours, dietary patterns, food acceptance and food neophobia in children with PKU compared with age/sex matched healthy children. Parental anxiety, coping strategies, and food neophobia were also examined. Further studies reported the validation of a food frequency questionnaire (FFQ) developed specifically for PKU for collecting data on habitual food intake and dietary patterns; development of national consensus statements for PKU on food labelling interpretation and protein allocation by the British Inherited Metabolic Disease Group (BIMDG) dietitians; and a randomised controlled trial to assess self-efficacy, label reading knowledge, and calculation of natural protein intake in caregivers/patients with PKU using a low protein multimedia diet app compared with using written/pictorial material.

Results: Children with PKU did not differ significantly from non-PKU children in most aspects of weaning progression, although they commenced weaning a month earlier, and experienced prolonged bottle and parental spoon feeding associated with parental anxiety. Teething and illness affected weaning protein substitute administration with difficulties peaking at age 10-18 months. Accelerated linear growth was observed in infants with PKU. Protein, carbohydrate and fat as a percentage of energy intake were comparable with control children up to 12 months of age, when carbohydrate increased, but fat decrease compared to controls. This difference was validated by the FFQ which demonstrated energy and macronutrient reproducibility and validity compared with 24-hour dietary recalls. All children (PKU and non-PKU) demonstrated a preference for sweet foods compared with savoury, bitter and sour foods despite the early and persistent exposure to bitter tasting protein substitutes in infancy in PKU. Children with PKU were more food neophobic than their parents and non-PKU peers. The 112 food statements developed by BIMDG dietitians to guide interpretation of food labels and allocation of protein in PKU were translated into a patient-friendly app. The patients/caregivers of younger children found the app particularly informative and there were trends toward improved protein calculation and labelling knowledge with frequent app users.

Conclusion: Timing of solid food and weaning protein substitute introduction, parental approach, and consistent feeding routines were important in aiding their acceptance. Systematic introduction of weaning protein substitute facilitated normal growth and feeding development although parents required support in managing the complexity of feeding and to ‘normalise’ mealtime social inclusivity. Neophobia played a significant role in food refusal in PKU and may be related to a fear of eating unfamiliar high phenylalanine/protein foods. Any preference for bitter tasting foods in PKU may be modulated by the continual use of artificially sweetened protein substitutes in childhood. Measurement of energy, macronutrient and individual food intake using the validated FFQ will be useful in assessing changes in dietary patterns over time in patients with PKU. The low protein diet app will support education of parents/caregivers, extended family and nursery/school employees. Collectively, these studies enhance knowledge and provide innovative practical tools that will improve dietary management of PKU and will assist health professionals to effectively support patients with PKU and their families.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):