Effect of a high protein meat diet on muscle and cognitive functions: a randomised controlled dietary intervention trial in healthy men

Clin Nutr. 2011 Jun;30(3):303-11. doi: 10.1016/j.clnu.2010.12.010. Epub 2011 Jan 15.


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.

Design: 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.

Conclusion: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Amino Acids, Branched-Chain / blood
  • Cognition*
  • Denmark
  • Diet
  • Dietary Proteins / adverse effects
  • Dietary Proteins / therapeutic use*
  • Humans
  • Male
  • Meat* / adverse effects
  • Muscle, Skeletal / physiology*
  • Nutritional Requirements
  • Phenylalanine / blood
  • Reaction Time
  • Single-Blind Method
  • Young Adult


  • Amino Acids, Branched-Chain
  • Dietary Proteins
  • Phenylalanine

Associated data

  • ClinicalTrials.gov/NCT00621231