Acceptability of a new modular protein substitute for the dietary treatment of phenylketonuria

The major source of protein in the dietary treatment of phenylketonuria (PK U) is a phenylalanine-free amino acid mixture. Traditionally, these medical products have also contained other nutrients and have been in powder form. However, their disagreeable taste and odour, the large volume required to provide sufficient protein and the inconvenience of their preparation and s torage have hindered compliance with consumption among adolescents and adul ts. We studied the acceptability of a new medical product for the treatment of PKU. This product, Phlexy-10 (SHS North America, Gaithersburg, MD, USA) , is available in three forms: sachets of premeasured powder to be constitu ted as a drink, fruit-flavoured bars and prefilled capsules. A vitamin-mine ral mixture is separately provided. The forms are interchangeable because e ach component (one sachet, one bar or 20 capsules) provides 10 g of amino a cids. Since the product is primarily a source of amino acids, protein requi rements can be met using a smaller volume than with traditional medical pro ducts. Eleven subjects enrolled in a 24-week trial that included clinical a nd laboratory evaluations. Nine subjects completed the study and 8 remained on the Phlexy-10 after the study. The powder drink was the favourite modul e used. One-third of the subjects included the bars and another third inclu ded the capsules in their regimens. The vitamin-mineral mixture was the lea st acceptable component. Mean weekly blood phenylalanine decreased by 40% f rom mean baseline levels. Blood concentrations of vitamins and minerals wer e normal except for a low zinc concentration in two subjects and a low vita min B(1)2 concentration in another. The lower caloric content and the separ ate vitamin-mineral mixture require careful monitoring of these nutrients. Phlexy-10 appears to be an adequate medical product for the treatment of PK U. Its convenience, flexibility of form and improved taste are appealing to many individuals on diet for PKU.