The effect of a controlled 8-week metabolic ward based lysine supplementation on muscle function, insulin sensitivity and leucine kinetics in young men.

Background & Aims: The 2007 FAO/WHO/UNU lysine requirement is 30 mgkg(-1)d(-1). Developing country populations may be at risk of lysine deficiency, with effects on muscle and its function. The effect of an 8 wk lysine supplementation diet on muscle mass and function was assessed.

Methods: Healthy, under and well-nourished men were studied before and after 8 wk, during which low (n=20) and high (n=20) lysine diets were consumed. The low lysine diets (∼25 and ∼40 mgkg(-1)d(-1) for under and well-nourished respectively) were based on the subjects' habitual lysine intake, while the high lysine diet supplied 80 mgkg(-1)d(-1). Anthropometry, muscle function, insulin sensitivity (IS) and leucine kinetics were measured before and after the experimental period.

Results: The high lysine diet had a small positive effect (about +7.5%) on muscle strength, but no effect on other parameters. Over the 8 wk period in the whole group, the change in muscle strength correlated with the change in muscle mass (r=0.5, P=0.001), while the change in muscle mass correlated with the change in IS (r=0.3, P=0.04), but there were no intake specific differences.

Conclusion: Over an 8 wk controlled feeding period, an intake of 80 mg lysine kg(-1)d(-1) had a small positive effect on muscle strength, but no other effects.