Because consuming medical food (also called formula) is so important to proper nutrition and metabolic control for individuals with PKU, dietitians often do not suggest a change if a patient is content with his or her current product. Dietitians will only recommend a change if the current medical food is not meeting nutritional needs or if the patient is not taking the full amount of medical food prescribed.

Getting the prescribed amount of medical food. Patients, especially teens and adults, often report that they can get “all but” one or two of the servings they should consume. Reasons for this include not wanting to bring medical food to school or work to being busy in the evening and forgetting the last serving. Glytactin is available in many forms (bars, drinks, powder, pudding, sachets) to make taking medical food more convenient, and studies show that patients are willing to take Glytactin products more often during the day than amino-acid based products.

Meeting nutritional needs. A change in medical food is indicated nutritionally when either the protein or the energy content of a product is not meeting a patient’s needs. Commonly, a product with a higher protein to energy ratio, such as Glytactin, is needed after infancy. This is a good time to consider Glytactin because children’s taste preferences are imprinted at an early age. Offering an alternative taste to amino-acid based formulas before age 2 years may enhance acceptance later on. More protein is also needed during adolescence or for patients who desire a post-workout protein supplement.

Phe prescription on Glytactin. What about the extra phenylalanine in GMP? Indeed, the Phe content is higher in products containing GMP; however, studies show an insignificant increase in blood phe in patients taking these medical foods. Glytactin-based medical foods have been used for young children and pregnant women who did not tolerate amino-acid based medical foods and they maintained blood phe in the target range of 120-360 μmol/L (2-6 mg/dL). For patients with severe forms of PKU, the Phe content of the Glytactin must be considered, however for patients with more moderate forms of PKU, the additional Phe is easily tolerated requiring no adjustment in Phe intake. For adults returning to diet, the Phe in Glytactin is usually a small contribution to the total Phe intake and as patients start consuming adequate protein and build lean body mass, they can tolerate the additional Phe.

Monitoring is important. As with all patients with PKU, close monitoring of nutritional intake and blood Phe is key to successful diet management.