Leucine is an indispensable amino acid which makes up 5 - 10% of protein. In skeletal muscles, leucine along with isoleucine and valine, constitute about 30% of the protein.

Intake of these three amino acids is suggesed to decrease rate of muscle protein degradation and help with physical and mental performance during exercise. Leucine is also a good source of energy. Of the total energy used, it contributes 3 - 4% during normal activity and upto 1% during exercise.

Human body is not able to produce leucine. Therefore, it is called essential amino acid and must be sourced from food.

Leucine Daily Requirements

Leucine requirement varies depending on life stage, gender and age. For Americans and Canadians, the US Food and Nutrition Board sets Dietary Reference Intakes (DRI), such as the Estimated Average Requirement (EAR) and Recommended Daily Allowances (RDA), of nutrients for healthy individuals. Here are the EAR and RDA for leucine. The recommendations are in mg per kg of body per day.

Note: The EAR is the daily average amount estimated to be sufficient for the average (median) healthy person. The RDA is the daily average estimated to be sufficient for most healhty individuals.

Age, gender, life stage group Leucine EAR (mg/kg/day)  Leucine RDA (mg/kg/day)
Infants
0–6 month   156
7–12 month 65 93
Children
1–3 years 48 63
4–8 years 40 49
Girls
9–13 years 38 47
14–18 years 35 44
Boys
9–13 years 40 49
14–18 years 38 47
Adult Men and Women
19 and older 34 42
Pregnant Women
All ages 45 56
Lactating Women
All ages 50 62

 

Leucine related content:
List of foods high or low in leucine

 

Sources:

Antti Mero (1999). Leucine Supplementation and Intensive Training. Sports Medicine. June 1999, Volume 27, Issue 6, pp 347–358.

Peter J. Garlick (2005). The Role of Leucine in the Regulation of Protein Metabolism. The Journal of Nutrition, Volume 135, Issue 6, June 2005, Pages 1553S–1556S.

Institute of Medicine (2006). Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: The National Academies Press.