NCT00972582

Upper Limit of Leucine Intake in Adults

Determination of the Tolerable Upper Limit of Leucine Intake in Adult Humans

• Status: Completed
• Phase: Phase 1
• Study type: Interventional
• Enrollment: 5 (actual)
• Sponsor: The Hospital for Sick Children · Academic / Other
• Sex: Male
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

Summary

When dietary amino acid supplements are consumed by humans they are normally in addition to their normal daily requirements. The investigators' laboratory played a leading role in defining the estimated average requirement (EAR) and the recommended dietary intake for the "essential" amino acids (Dietary Reference Intakes 2005). The other important but less well studied component of Dietary Reference Intakes (DRI) is - What is a safe upper limit of intake? The investigators now propose to determine the safe upper limits of the dietary essential amino acids. The recently published DRI (2005) defines the Tolerable Upper Intake Level (UL) as 'the highest average daily nutrient intake level that is likely to pose no risk of adverse health effects to almost all individuals in the general population.' As intake increases above the UL, the potential risk of adverse effects may increase'. In this proposal, the investigators define a novel method to define the safe upper limit where the 'maximum oxidative potential' of an amino acid identifies the 'metabolic limit' to dispose the amino acid. Intakes of amino acid above this level will increase the potential for adverse effects to appear.

Detailed description

The objective of the study will be to determine the 'metabolic limit' of leucine oxidation in healthy young men by: A) Measuring leucine oxidation in response to short term (8 hr) graded excess leucine intake B) Correlating changes in leucine oxidation with changes in plasma concentrations of keto-isocaproic acid (KIC, the first breakdown product of leucine metabolism), other essential amino acids, ammonia, urea, creatinine, glucose, insulin, and electrolytes (sodium, potassium, chloride) to identify potential biomarkers C) Correlating changes in leucine oxidation with changes in urinary excretion of leucine and ketoisocaproic acid (KIC), urea and creatinine to identify potential biomarkers

Conditions

• Healthy

Interventions

Type	Name	Description
DIETARY_SUPPLEMENT	Leucine Increase	Graded stepwise increases in leucine intakes (50, 250, 500, 750, 1000, 1250 and 1500mg/kg/day)

Timeline

• Start date: 2009-05-01
• Primary completion: 2010-02-01
• Completion: 2010-02-01
• First posted: 2009-09-07
• Last updated: 2013-07-29

Locations

1 site across 1 country: Canada