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A low amino acid (AA)/protein diet is the principal treatment for many inherited amino acid disorders (IMDs). Due to their low AA content, plant foods constitute an essential part of diet therapy. However, data on their AA composition are limited, which leads to an estimation of AA intake from protein content rather than an accurate calculation of true AA intake. This study describes the AA content of a total of 73 plant foods (fruits, n = 12; vegetables, n = 51; and other plant foods, n = 10), with the analysis commissioned by the UK National Society for Phenylketonuria (NSPKU) over 15 years. For all fruits and some vegetables (e.g., rocket, watercress and pea shoots), raw samples were used during analysis. All other vegetables were cooked prior to analysis to represent the usual condition of the food at the time of serving. AA analysis was performed with ion exchange chromatography. The median percentage of protein was 2.0% [0.6–5.4%] for the fruits and vegetables analysed (n = 56), although higher in vegetables than in fruits. Each of the five reported AAs (leucine, lysine, phenylalanine, tyrosine, and methionine) supplied 1–5% per g of protein content. From the heterogeneous range of plant foods analysed, the AA/protein ratios differed significantly (2–5% in fruits and 1–9% in vegetables). There was a strong correlation between the amounts of each of the five AAs in the plant foods, but only a small, moderate correlation between the protein and AA content. Overall, this study provides data on the AA content of several plant foods, which are suitable for patients treated with a low AA/protein diet, including many novel plant options. However, only a limited range of fruits and vegetables were analysed due to the high costs of analysis. Hence, more extensive studies with an increased number of plant foods prepared by different cooking methods and replicate samples are necessary, particularly to examine the relationship between the protein and AA content in depth.

Solid food introduction may create anxiety for parents of children with phenylketonuria (PKU) due to the burden associated with protein substitute (PS) administration and natural protein restriction. In a longitudinal, prospective study, 20 mothers of children with PKU and 20 non-PKU control mothers completed 4 questionnaires (mealtime emotions, feed-time, Beck&rsquo, s anxiety inventory and the coping health inventory for parents), examining parent/child mealtime emotions, anxiety, stress and coping strategies at child ages: weaning start, 8 months (m), 12 m, 15 m, 18 m and 24 m. Overall, mothers of children with PKU cope well with solid food introduction when applying a low-phenylalanine diet, with comparable low levels of stress and anxiety reported in both PKU and non-PKU groups. However, mothers of children with PKU reported peak scores in anxiety for emotive/cognitive symptoms at a child age of 15 m, and higher use of coping strategies at 15 m and 24 m (p &lt, 0.05) of age. Generally, there was a trend that maternal anxiety regarding child rejection of PS increased with time, peaking between 12&ndash, 24 m. In PKU, a child age of 12&ndash, 18 m is identified as a key period when mothers feel most anxious/stressed with feeding, coinciding with raised blood phenylalanine levels probably associated with teething, illness and developing independence. Health professionals should be conscious of this vulnerable period and be prepared to offer more directional support as required.

Growth issues have been observed in young children with phenylketonuria (PKU), but studies are conflicting. In infancy, there is an increasing trend to introduce a second-stage semi-solid weaning protein substitute (WPS) but there is concern that this may not meet energy requirements. In this longitudinal, prospective study, 20 children with PKU transitioning to a WPS, and 20 non-PKU controls were observed monthly from weaning commencement (4&ndash, 6 months) to 12 m and at 15, 18 and 24 months of age for: weight, length, head circumference, body mass index (BMI), energy and macronutrient intake. Growth parameters were within normal range at all ages in both groups with no significant difference in mean z-scores except for accelerated length in the PKU group. No child with PKU had z-scores &lt, &minus, 2 for any growth parameter at age 2 years. Total protein and energy intake in both groups were similar at all ages, however, from 12&ndash, 24 months in the PKU group, the percentage of energy intake from carbohydrate increased (60%) but from fat decreased (25%) and inversely for controls (48% and 36%). In PKU, use of low volume WPS meets Phe-free protein requirements, facilitates transition to solid foods and supports normal growth. Further longitudinal study of growth, body composition and energy/nutrient intakes in early childhood are required to identify any changing trends.

Weaning is complex for children with phenylketonuria (PKU). Breastmilk/infant formula and phenylalanine (Phe)-free infant protein-substitute (PS) are gradually replaced with equivalent amounts of Phe-containing food, a semi-solid/spoonable weaning PS and special low-protein foods. In PKU, feeding patterns/practices during weaning in PKU have not been formally evaluated. In this longitudinal, prospective, case-control study (n = 20) infants with PKU transitioning to a second-stage PS, were recruited at weaning (4&ndash, 6 months) for a comparison of feeding practices and development with non-PKU infants. Subjects were monitored monthly to 12 months and at age 15 months, 18 months and 24 months for: feeding progression, food textures, motor skill development and self-feeding, feeding environment, gastrointestinal symptoms, and negative feeding behaviours. Children with PKU had comparable weaning progression to non-PKU infants including texture acceptance, infant formula volume and self-feeding skills. However, children with PKU had more prolonged Phe-free infant formula bottle-feeding and parental spoon feeding than controls, fewer meals/snacks per day, and experienced more flatulence (p = 0.0005), burping (p = 0.001), retching (p = 0.03), and less regurgitation (p = 0.003). Negative behaviours associated with PS at age 10&ndash, 18 months, coincided with the age of teething. Use of semi-solid PS in PKU supports normal weaning development/progression but parents require support to manage the complexity of feeding and to normalise the social inclusivity of their child&rsquo, s family food environment. Further study regarding parental anxiety associated with mealtimes is required.

In phenylketonuria (PKU), variable dietary advice provided by health professionals and social media leads to uncertainty for patients/caregivers reliant on accurate, evidence based dietary information. Over four years, 112 consensus statements concerning the allocation of foods in a low phenylalanine diet for PKU were developed by the British Inherited Metabolic Disease Dietitians Group (BIMDG-DG) from 34 PKU treatment centres, utilising 10 rounds of Delphi consultation to gain a majority (&ge, 75%) decision. A mean of 29 UK dietitians (range: 18&ndash, 40) and 18 treatment centres (range: 13&ndash, 23) contributed in each round. Statements encompassed all foods/food groups divided into four categories based on defined protein/phenylalanine content: (1) foods high in protein/phenylalanine (best avoided), (2) foods allowed without restriction including fruit/vegetables containing phenylalanine &le, 75 mg/100 g and most foods containing protein &le, 0.5 g/100 g, (3) foods that should be calculated/weighed as an exchange food if they contain protein exchange ingredients (categorized into foods with a protein content of: &gt, 0.1 g/100 g (milk/plant milks only), &gt, 0.5 g/100 g (bread/pasta/cereal/flours), &gt, 1 g/100 g (cook-in/table-top sauces/dressings), &gt, 1.5 g/100 g (soya sauces)), and (4) fruit/vegetables containing phenylalanine &gt, 75 mg/100 g allocated as part of the protein/phenylalanine exchange system. These statements have been endorsed and translated into practical dietary management advice by the medical advisory dietitians for the National Society for PKU (NSPKU).