Phenylketonuric diet negatively impacts on butyrate productionOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study examined how the phenylalanine (Phe) restricted diet used to treat phenylketonuria (PKU) affects gut microbiota and short chain fatty acid (SCFA) production. Researchers compared dietary intakes, gut microbiota biodiversity, and fecal SCFAs between children on a low-Phe diet and children with unrestricted diets. Fecal microbiota was analyzed using denaturing gradient gel electrophoresis (DGGE) and Real-time PCR, and SCFAs were quantified by gas chromatography.
Who was studied?
The study enrolled 21 children with PKU, who followed a low-Phe diet with Phe-free l-amino acid supplementation, and 21 children with mild hyperphenylalaninemia (MHP), who followed an unrestricted diet. The two groups were matched for gender, age, and body mass index z-score. This case-control design allowed direct comparison of diet-driven microbiota differences between the two pediatric groups.
What were the most important findings?
PKU children showed higher carbohydrate, fiber, and vegetable intake, along with higher glycemic index and glycemic load, compared with MHP children. Despite this, PKU children had lower gut microbial diversity and significantly decreased fecal butyrate content. Faecalibacterium spp. and Roseburia spp., two of the most abundant butyrate-producing genera, were significantly depleted in the PKU group compared with MHP children.
What are the greatest implications of this study?
These findings suggest that the low-Phe diet, despite increasing carbohydrate and fiber intake, alters the quality of substrates available for microbial fermentation in a way that reduces butyrate production. Since Faecalibacterium prausnitzii and related butyrate producers are considered beneficial, anti-inflammatory commensals, their depletion in PKU children raises concern about gut health in this population. The authors call for further studies to characterize the microbial species affected by the PKU diet, which could eventually support the use of prebiotic or probiotic supplementation in these children.