Long-term leucine supplementation does not increase muscle mass or strength in healthy elderly men.
BACKGROUND
It has been reported that the blunted muscle protein synthetic response to food intake in the elderly can be normalized by increasing the leucine content of a meal.


OBJECTIVE
The objective was to assess the effect of 3 mo of leucine supplementation on muscle mass and strength in healthy elderly men.


METHODS
Thirty healthy elderly men with a mean (+/-SEM) age of 71 +/- 4 y and body mass index (BMI; in kg/m(2)) of 26.1 +/- 0.5 were randomly assigned to either a placebo-supplemented (n = 15) or leucine-supplemented (n = 15) group. Leucine or placebo (2.5 g) was administered with each main meal during a 3-mo intervention period. Whole-body insulin sensitivity, muscle strength (one-repetition maximum), muscle mass (measured by computed tomography and dual-energy X-ray absorptiometry), myosin heavy chain isoform distribution, and plasma amino acid and lipid profiles were assessed before, during, and/or after the intervention period.


RESULTS
No changes in skeletal muscle mass or strength were observed over time in either the leucine- or placebo-supplemented group. No improvements in indexes of whole-body insulin sensitivity (oral glucose insulin sensitivity index and the homeostasis model assessment of insulin resistance), blood glycated hemoglobin content, or the plasma lipid profile were observed.


CONCLUSIONS
Long-term leucine supplementation (7.5 g/d) does not augment skeletal muscle mass or strength and does not improve glycemic control or the blood lipid profile in healthy elderly men. This trial was registered at clinicaltrials.gov as NCT00807508.
Verhoeven
Suzanne
S
Department of Human Movement Sciences, Nutrition and Toxicology Research Institute, Maastricht, Maastricht University, Maastricht, Netherlands.
Vanschoonbeek
Kristof
K
Verdijk
Lex B
LB
Koopman
René
R
Wodzig
Will K W H
WK
Dendale
Paul
P
van Loon
Luc J C
LJ