The University of Southampton
University of Southampton Institutional Repository

Endogenous glycine and tyrosine production is maintained in adults consuming a marginal-protein diet

Record type: Article

Background: The adequacy of indispensable amino acid supplies has received much attention in studies of protein requirements, but the availability of nitrogen for synthesis and maintenance of the supply of dispensable amino acids has been overlooked.

Objective: We aimed to determine whether nitrogen balance and the endogenous supply of the dispensable amino acids glycine and tyrosine can be maintained with a marginal protein intake.

Design: Phenylalanine, glycine, and tyrosine kinetics were measured in young adults (6 men, 6 women) on 4 occasions during a reduction in habitual protein intake (1.13 g·kg-1·d-1) to a marginal intake (0.75 g·kg-1·d-1) by using a multiple stable-isotope-infusion protocol.

Results: During the 10-d period of marginal protein intake, nitrogen excretion fell initially, then remained constant such that nitrogen balance was negative for the first 2 d and then positive or zero thereafter. Whole-body protein degradation and synthesis predicted from phenylalanine kinetics declined significantly (P < 0.05) over the period of marginal protein intake. Despite the reduction in the amount of glycine and tyrosine derived from whole-body proteolysis, the fluxes of glycine and tyrosine were maintained.

Conclusions: The results show that adaptation to a marginal intake of dietary protein consisted of an overall reduction in whole-body protein turnover, net protein catabolism, and the rate of nitrogen excretion. The conserved nitrogen was sufficient to maintain the endogenous synthesis and hence the supply of glycine and tyrosine.

PDF 511.pdf - Version of Record
Restricted to Repository staff only
Download (221kB)

Citation

Gibson, Neil R., Jahoor, Farook, Ware, Lisa and Jackson, Alan A. (2002) Endogenous glycine and tyrosine production is maintained in adults consuming a marginal-protein diet American Journal of Clinical Nutrition, 75, (3), pp. 511-518. (PMID:11864857).

More information

Published date: March 2002
Additional Information: Original research communication
Keywords: phenylalanine, glycine, tyrosine kinetics, marginal protein intake, nitrogen balance, protein requirements, dispensable amino acids

Identifiers

Local EPrints ID: 25533
URI: http://eprints.soton.ac.uk/id/eprint/25533
ISSN: 0002-9165
PURE UUID: c2c1d074-ef03-45cf-945c-109faa0ee00c

Catalogue record

Date deposited: 11 Apr 2006
Last modified: 17 Jul 2017 16:10

Export record

Contributors

Author: Neil R. Gibson
Author: Farook Jahoor
Author: Lisa Ware
Author: Alan A. Jackson

University divisions


Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×