The first GMP human feeding trial was published in February in the Journal of Inherited Metabolic Disorders. In it, Ney and her team describe the experience of an individual with PKU who volunteered to consume an all-GMP diet for 10 weeks. As the paper explains, not only did the subject enjoy the GMP-fortified snack bar, pudding and sports beverage that supplied most of his daily protein, but the amount of phenylalanine in his blood actually starting going down after he ate these items for a couple of weeks.
"And because the subject enjoyed the GMP foods, he was more inclined to eat them throughout the day, which helps keep the body's protein metabolism running efficiently all day long," says Ney. "When he went back to the amino acid formula, he went back to drinking it all in one sitting."
Ney's new study, published in the April issue of the American Journal of Clinical Nutrition and appearing online on Feb. 25, describes an 11-person trial of shorter duration involving PKU patients receiving care from UW-Madison's Waisman Center who agreed to spend six days at the University Hospital's Clinical and Translational Research Core. In the study, subjects adhered to the amino acid formula diet for four days, and then switched to the GMP diet for the following four. (Subjects spent the first two days of the study at home.) In the end, no adverse health problems were found, and 10 of 11 subjects claimed to prefer the GMP diet, making the bottom line of this study the same as the first that GMP is safe and acceptable.
In this shorter study, variations were seen among individual subjects, but the overall blood phenylalanine levels measured after meals were comparable in the two diets. Additionally, the GMP diet improved protein metabolism compared to the amino acid formula.
Members of the PKU community have been eagerly monitoring the progress of this research project for nearly a decade, since UW-Madison
|Contact: Denise Ney|
University of Wisconsin-Madison