Healthy
Conditions
Keywords
leucine intake, tolerable upper limit, adults, amino acid supplements, Excessive Leucine Intake
Brief 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
Interventions
DIETARY_SUPPLEMENTLeucine Increase
Graded stepwise increases in leucine intakes (50, 250, 500, 750, 1000, 1250 and 1500mg/kg/day)
Sponsors
The Hospital for Sick Children
Study design
Allocation
NON_RANDOMIZED
Intervention model
SINGLE_GROUP
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
MALE
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Male * 18-35 years old
Exclusion criteria
* Report a recent history of sudden weight loss * Have unusual dietary habits such as chronic consumption of caffeinated beverages or alcohol * Have any endocrine disorders * Are currently using any prescribed medications
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Breath carbon dioxide production | Study Visits 1-7 (-45min,-30min,-15min, +2.5hrs, +3hrs, +3.5Hrs +4hrs) |
Secondary
| Measure | Time frame |
|---|---|
| Plasma | Study Visits 1-7 (Hourly) |
| Urine | Study Visits 1-7 (8hr timepoint) |
| VCO2 | Study Visits 1-7 (after 5hr meal) |
Countries
Canada
Outcome results
None listed