Knowledge, perceptions and behaviours regarding dietary management of adults living with phenylketonuria.

BACKGROUND: Lifelong dietary treatment remains the mainstay for many with phenylketonuria (PKU); however, adherence is known to reduce with age. It remains unclear whether knowledge and perceptions of the PKU diet amongst adults with PKU influence dietary behaviours. METHODS: A nationwide questionnaire survey was performed to investigate the knowledge and perceptions, and associated diet behaviours of adults with PKU in the UK. The survey was sent to adults with PKU under the care of the host hospital and members of the National Society of PKU. RESULTS: One hundred and thirty-seven respondents (n = 78 females, 56.9%) completed the survey with a mean age of 34 years and 4 months (16-65 years). Sixty (43.8%) respondents had always followed a PKU diet, 39 (28.5%) returned to diet and 35 (25.5%) were off diet. Overall mean ± SD knowledge score was 75.2% ± 13.4%, with significantly higher scores for knowledge of PKU (80.7% ± 16.2%) compared to knowledge specifically of the PKU diet (72.6% ± 14.5%, p < 0.001). Knowledge was associated with dietary adherence. Respondents who always followed a PKU diet had similar knowledge to those who returned to diet, whereas respondents off diet had significantly lower scores. Perception of the diet was not a predictor of dietary adherence, with the exception of whether patients had concerns for their long-term health when on diet or felt well when not following a diet. CONCLUSIONS: The present study highlights the importance of ongoing dietetic input in building knowledge and skills for dietary management. Further research is needed to understand the motivators and beliefs that influence dietary adherence.

Protein status in phenylketonuria: A scoping review.

BACKGROUND & AIMS: The physical and functional outcomes of lifelong treatment with a phenylalanine restricted diet for the management of Phenylketonuria (PKU) remain unknown. Given that the mainstay of dietary management consists of modifying the sources of ingested protein, various aspects of body protein status could be compromised. OBJECTIVES: To examine the existing evidence regarding the protein status of people with PKU and identify nutritional and lifestyle variables that influence protein status. ELIGIBILITY CRITERIA: Studies reporting anthropometric, biochemical and/or functional measurements of body protein status in people with PKU were eligible. SOURCE OF EVIDENCE: MEDLINE (Ovid), Embase (Ovid), CENTRAL, Web of Science and Scopus, and conference abstracts. RESULTS: Seventy studies were included in the review. The majority of studies assessing protein status based on anthropometric measurements observed no differences between people with PKU and controls, although deficits in muscle mass were reported within PKU cohorts. Findings for biochemical assessment of protein status were mixed and limited studies assessed protein status using functional measures. Factors such as participant age, sex, metabolic control, protein source, type of protein substitute, and pharmacological treatments were found to modulate protein status of people with PKU. CONCLUSIONS: Findings were inconclusive regarding body protein status in people with PKU. The relationship between diet and protein status outcomes remains unclear and further research is warranted to determine the impact of dietary regimens on physical and functional outcomes, and to understand the best clinical assessments to reliably monitor the protein status in people with PKU.