Specific prebiotics in a formula for infants with Phenylketonuria

Abstract

Objective This exploratory study investigated the influence of adding a patented, specific mixture of prebiotic oligosaccharides (scGOS/lcFOS [9:1 ratio], Danone Research) to a protein substitute suitable for infants with Phenylketonuria (PKU); PKU Anamix Infant (Nutricia). Design This was an 8-week open-label, single-arm, pilot intervention study in 9 infants (8-week median age) diagnosed with PKU. On study entry, infants were prescribed PKU Anamix Infant to replace an infant phenylalanine-free protein substitute without prebiotics (IPS). Blood phenylalanine concentrations were monitored and stool samples analyzed for pH/bacterial groups. Results PKU Anamix infant was well tolerated and accepted with no adverse events reported. Overall, plasma phenylalanine and tyrosine concentrations were maintained within target ranges throughout the study (120–360 μmol/l phenylalanine, 30–100 μmol/l tyrosine). All infants exhibited microbiota dominated by bifidobacteria (median 58.97% at Week 8), although no statistically significant change from baseline was observed at study endpoint. No infants showed abnormally high levels of Clostridium histolyticum/lituseburense or potentially pathogenic enterobacteriaceae at any point during the study. A significant reduction in median stool pH versus baseline was observed at Week 4 (pH reduced from 6.79 to 5.83), but this significance was not present at Week 8 (pH = 6.61). Conclusions PKU Anamix Infant maintains phenylalanine control in line with established IPS without prebiotics and maintains levels of bifidobacteria and lowers stool pH. In exclusively breast-fed infants the latter two factors have been associated with a reduced risk of infection and may be of particular importance in infants with PKU.