Protein requirements in adults with phenylketonuria and bioavailability of glycomacropeptide compared to an <scp>l</scp>‐amino acid‐based product
Bibliographic record
Abstract
Abstract Background Phenylketonuria (PKU) is caused by phenylalanine hydroxylase deficiency. Treatment is primarily a low‐Phe diet combined with l‐amino acid‐based products (l‐AA). Protein requirements in adults with PKU have not been directly determined. A formula with glycomacropeptide (GMP) and low phenylalanine is available, yet untested for optimal protein synthesis. Objectives To determine the protein requirements in adults with PKU and the bioavailability of GMP‐AA in the same patients using the indicator amino acid oxidation (IAAO) technique. Methods Each participant was allocated to 7 separate l‐AA intakes (range: 0.1–1.8 g/kg/day) in Experiment 1. In Experiment 2, the same patients participated in 4 GMP‐AA intakes (range: 0.1–0.9 g/kg/day). The IAAO method with l‐[1‐13C]‐lysine as the indicator amino acid and its oxidation to 13CO2 was used as the primary indicator of protein synthesis. Protein requirements were identified with a breakpoint, and bioavailability was determined by comparing 13CO2 slope from GMP‐AA versus l‐AA. Results Six adults with PKU (4 M: 2F) completed a total of 54 study days over the 2 experiments. The estimated average requirement (EAR) for protein was determined to be 1.11 g/kg/day (R2 = 0.20). The bioavailability of protein from GMP‐AA was determined to be 99.98%, which was high and near to 100% comparable to l‐AA; although, the results apply only to the tested GMP‐AA blend. Conclusions To our knowledge, this is the first study to directly define a quantitative protein requirement and indicates that current PKU protein recommendations for adults with PKU may be underestimated. The bioavailability of protein in the GMP‐AA blend was high and optimal for protein synthesis in adults with PKU.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".