Effect of a high protein meat diet on muscle and cognitive functions: a randomised controlled dietary intervention trial in healthy men.
BACKGROUND
Recommendations to use other criteria than N-balance for defining protein requirements have been proposed. However, little evidence to support other measures such as physiological functions is available.


OBJECTIVE
To investigate the effects of a usual (UP) versus a high protein (HP) diet on muscle function, cognitive function, quality of life and biochemical regulators of protein metabolism.


METHODS
A randomised intervention study was conducted with 23 healthy males (aged 19-31 yrs). All subjects consumed a Usual Protein (UP) diet (1.5 g protein/kg BW) for a 1-wk run-in period before the intervention period where they were assigned to either a UP or a High Protein (HP) diet (3.0 g protein/kg BW) for 3-wks with controlled intake of food and beverages. Blood and urine samples were taken along with measurements of physiological functions at baseline and at the end of the intervention period.


RESULTS
The HP group improved their reaction time significantly compared with the UP group. Branched chain amino acids and phenylalanine in plasma were significantly increased following the HP diet, which may explain the improved reaction time.


CONCLUSIONS
Healthy young males fed a HP diet improved reaction time. No adverse effects of the HP diet were observed. This trial was registered at www.clinicaltrials.gov as NCT00621231.
Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Denmark. lene.holm@rh.regionh.dk
Lene H
LH
Jakobsen
Jens
J
Kondrup
Maria
M
Zellner
Inge
I
Tetens
Erich
E
Roth
D000293:Adolescent; D000328:Adult; D000597:Amino Acids, Branched-Chain / Q000097:blood; D003071:Cognition; D003718:Denmark; D004032:Diet; D004044:Dietary Proteins / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008460:Meat / Q000009:adverse effects; D018482:Muscle, Skeletal / Q000502:physiology*; D009751:Nutritional Requirements; D010649:Phenylalanine / Q000097:blood; D011930:Reaction Time; D016037:Single-Blind Method; D055815:Young Adult
D000597:Amino Acids, Branched-Chain; D004044:Dietary Proteins; D010649:Phenylalanine