Phillips · Advances in nutrition (Bethesda, Md.) 2020 · narrative review · n=?

Optimizing Adult Protein Intake During Catabolic Health Conditions.

Cited 62 times in the scientific literature.

Level 5 - mechanism / opinion, no new human data

Narrative review without systematic review methodology or meta-analysis

PubMed 32666115 · doi:10.1093/advances/nmaa047 · record verified 2026-08-30

What was done

This narrative review examined the adequacy of current dietary reference intakes for protein and indispensable amino acids during catabolic conditions. It evaluated the standard protein Recommended Dietary Allowance (RDA) and essential amino acid requirements, focusing on leucine needs during aging, inactivity, bed rest, and metabolic dysfunction such as type 2 diabetes.

What was found

The abstract reports that the current RDA for protein is 0.8 g/kg body weight and the RDA for leucine is 42 mg/kg body weight. It states that leucine requirements to optimize metabolic regulation and skeletal muscle protein synthesis are approximately 100 to 110 mg/kg body weight. No other empirical numbers, effect sizes, or study counts are provided in the abstract.

Why it matters

Current protein RDAs focus on avoiding deficiency rather than optimizing metabolic outcomes. Re-evaluating protein and leucine targets may help preserve skeletal muscle and improve metabolic regulation during acute or chronic catabolic stress.

Limits

This is a narrative review with no systematic search methodology or quantitative meta-analysis reported in the abstract. The abstract includes no primary clinical trial outcome data, sample sizes, or analyses of potential adverse effects associated with higher intake levels.

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