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Upper Limit of Leucine Intake in Adults

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00972582
Recruitment Status : Completed
First Posted : September 7, 2009
Last Update Posted : July 29, 2013
Information provided by (Responsible Party):
Dr. Paul Pencharz, The Hospital for Sick Children

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.

Condition or disease Intervention/treatment Phase
Healthy Dietary Supplement: Leucine Increase Phase 1

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

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 5 participants
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: Single (Participant)
Official Title: Determination of the Tolerable Upper Limit of Leucine Intake in Adult Humans
Study Start Date : May 2009
Actual Primary Completion Date : February 2010
Actual Study Completion Date : February 2010

Resource links provided by the National Library of Medicine

Drug Information available for: Leucine

Arm Intervention/treatment
Experimental: Leucine Dietary Supplement: Leucine Increase
Graded stepwise increases in leucine intakes (50, 250, 500, 750, 1000, 1250 and 1500mg/kg/day)

Primary Outcome Measures :
  1. Breath carbon dioxide production [ Time Frame: Study Visits 1-7 (-45min,-30min,-15min, +2.5hrs, +3hrs, +3.5Hrs +4hrs) ]

Secondary Outcome Measures :
  1. Plasma [ Time Frame: Study Visits 1-7 (Hourly) ]
  2. Urine [ Time Frame: Study Visits 1-7 (8hr timepoint) ]
  3. VCO2 [ Time Frame: Study Visits 1-7 (after 5hr meal) ]

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 35 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts 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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00972582

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Canada, Ontario
The Hospital for Sick Children
Toronto, Ontario, Canada
Sponsors and Collaborators
The Hospital for Sick Children
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Principal Investigator: Paul B Pencharz, MD The Hospital for Sick Children, Toronto, Canada
Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: Dr. Paul Pencharz, Emeritus Scientist, The Hospital for Sick Children Identifier: NCT00972582    
Other Study ID Numbers: 1000012066
First Posted: September 7, 2009    Key Record Dates
Last Update Posted: July 29, 2013
Last Verified: July 2013
Keywords provided by Dr. Paul Pencharz, The Hospital for Sick Children:
leucine intake
tolerable upper limit
amino acid supplements
Excessive Leucine Intake