Evidence that protein requirements have been significantly underestimated.
Level 5 - mechanism / opinion, no new human data
Narrative review presenting methodological critique and re-analyses without a systematic review protocol
PubMed 19841581 · doi:10.1097/MCO.0b013e328332f9b7
What was done
The authors reviewed methodologies used to determine adult human protein requirements, comparing the traditional nitrogen balance method (which informs Dietary Reference Intake recommendations of 0.66 g/kg/day mean and 0.8 g/kg/day safe intake) against two approaches: a two-phase linear regression re-analysis of existing nitrogen balance data, and experimental measurements using the indicator amino acid oxidation (IAAO) technique in adult men.
What was found
Re-analysis of existing nitrogen balance studies using two-phase linear regression yielded estimated mean and safe protein requirements of 0.91 and 0.99 g/kg/day, respectively. Measurements using the IAAO technique in adult men determined mean and safe requirements to be 0.93 and 1.2 g/kg/day, representing values 41% and 50% higher than standard Dietary Reference Intake recommendations.
Why it matters
This paper challenges existing dietary guidelines by proposing that standard nitrogen balance methodology underestimates baseline human protein needs.
Limits
The abstract describes a narrative review and does not state the number of studies or participant sample sizes included. The reported IAAO experimental values are limited to adult men, and conclusions rely on the validity of specific kinetic and statistical modeling assumptions.
Cited by
- supports Alternative protein requirement assessment methods using stable isotopes indicate that human protein requirements to maintain balance are closer to 1.2 grams per kilogram of body weight per day.