Saturated Fat Versus Monounsaturated Fat and Insulin Action

November 30, 2015 updated by: Craig Lawrence Kien, University of Vermont

Palmitate Metabolism and Insulin Resistance

High intakes of saturated fat are associated with diabetes. Our work has shown that the two most common fatty acids in the North American diet, palmitic acid (saturated fat) and oleic acid (monounsaturated fat) are metabolized differently and have opposite effects on fat burning. The proposed study will examine biochemical and molecular mechanisms for how a high saturated fat diet versus a low saturated fat/high monounsaturated fat diet alters the action of the hormone, insulin, in skeletal muscle.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Palmitic acid (PA), impairs insulin sensitivity in skeletal muscle, and replacing PA in the diet with oleic acid (OA), a monounsaturated fatty acid (FA), may be beneficial. The first objective of this project is to understand the effects on lipid metabolism and skeletal muscle lipid composition, insulin signaling, and inflammatory signaling of two common variations in FA composition of the diet: (1) The typical intake of North America where PA and OA are present in equal proportions (HI PA diet). (2) The Mediterranean FA composition in which PA is much lower and OA much higher (HI OA diet). PA may induce insulin resistance in skeletal muscle cells via its accumulation in lipids within muscle cells and via activation of inflammatory signaling. The second objective of this project is to assess the hypothesis that a high intake of PA will down-regulate its own one-carbon (initial) oxidation, leading to increased inflammatory signaling and decreased insulin signaling. However, there is literature evidence that FA may induce defects in insulin signaling, if FA are not completely oxidized; therefore, the third objective is to assess the hypotheses that a high PA diet may decrease complete oxidation of FA and possibly accelerate initial FA oxidation. A double-masked, cross-over trial of the effects of a high PA diet versus a high OA/low PA diet in 16 overweight or obese subjects and 16 lean subjects (aged 18 - 40 yr) will be conducted to investigate the following Specific Aims:

  1. To test the hypothesis that increased intake of PA will cause a decreased rate of [1-13C]-PA oxidation and will be associated with: (a) increased inflammatory signaling, within the muscle and by peripheral blood mononuclear cells; (b) Decreased insulin signaling as characterized by decreased, whole body, peripheral insulin sensitivity (euglycemic/hyperinsulinemic clamp) and, in skeletal muscle, decreased phospho-AKT (Ser473), increased phospho-IRS-1 (Ser636/Ser639), decreased tyrosine phosphorylation of IRS-1, and decreased membrane content of GLUT4.
  2. To test the hypothesis that increased intake of PA will cause less complete mitochondrial fatty acid oxidation, perhaps associated with dysfunction of the TCA cycle and increased reactive oxygen species formation. This hypothesis will be tested by measuring whole body and muscle (upper limb) relative rates of oxidation of [13-13C]-PA and [1-13C]-PA and by determining the serum profile of acylcarnitines, the urine concentrations of organic acids, and muscle concentrations of protein carbonyls.
  3. To test the hypothesis that a high PA diet will lead to less complete oxidation of FA, less insulin signaling in skeletal muscle in response to a test meal, less whole body insulin sensitivity, increased dysfunction of the TCA cycle, and greater reactive oxygen species formation compared to the results obtained in obese versus lean humans.

Study Type

Interventional

Enrollment (Actual)

70

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Vermont
      • Burlington, Vermont, United States, 05401
        • The Unversity of Vermont Clinical Research Center at Fletcher Allen Health Care

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 40 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • healthy young adults,
  • 18 - 40 years of age

Exclusion Criteria:

  • regular aerobic exercise training,
  • dyslipidemia, and
  • type 2 diabetes or insulin resistance

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: PREVENTION
  • Allocation: RANDOMIZED
  • Interventional Model: CROSSOVER
  • Masking: QUADRUPLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: High palmitate or high oleate diet.
This is a solid food diet in which vegetable oils are used to create a dietary fat composition similar to the average American/Western diet in which palmitic and oleic acid are ingested in approximately equal amounts (high palmitate diet) or a composition similar to the Mediterranean Diet (low palmitate, high oleate, using hazelnut oil as the source of fat). There are no interventions other than the diet itself.
Dietary supplement: High palmitate or high oleate diet.
High palmitate diet composition: Fat, 40.4% kcal; palmitic acid, 16.0% kcal; oleic acid,16.2% kcal. High oleate diet composition: Fat, 40.1% kcal; palmitic acid, 2.4% kcal; oleic acid, 28.8% kcal
EXPERIMENTAL: high palmitate or high oleate diet
This is a solid food diet in which vegetable oils are used to create a dietary fat composition similar to the average American/Western diet in which palmitic and oleic acid are ingested in approximately equal amounts (high palmitate diet) or a composition similar to the Mediterranean Diet (low palmitate, high oleate, using hazelnut oil as the source of fat). There are no interventions other than the diet itself.
Dietary supplement: High palmitate or high oleate diet.
High palmitate diet composition: Fat, 40.4% kcal; palmitic acid, 16.0% kcal; oleic acid,16.2% kcal. High oleate diet composition: Fat, 40.1% kcal; palmitic acid, 2.4% kcal; oleic acid, 28.8% kcal

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Whether increased palmitate balance (as measured by intake and the rate of [1-13C]-PA oxidation) causes increased insulin resistance and increased inflammatory signaling by peripheral blood mononuclear cells
Time Frame: up to 4 yr
Insulin sensitivity, inflammatory signaling, palmitate balance, and incomplete oxidation of palmitate in lean and obese young adults.
up to 4 yr

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
We will examine the link between palmitate intake and balance and oxidative stress measured using muscle and peripheral blood markers of oxidative stress and antioxidant responses.
Time Frame: up to 4 yr
activation of c-Jun N-terminal kinase (JNK) and heme oxygenase 1 in skeletal muscle in response to the diets.
up to 4 yr

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Vermont

Investigators

  • Principal Investigator: Craig L. Kien, M.D, Ph.D., The University of Vermont

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

April 1, 2010

Primary Completion (ACTUAL)

November 1, 2015

Study Completion (ACTUAL)

November 1, 2015

Study Registration Dates

First Submitted

May 29, 2012

First Submitted That Met QC Criteria

June 4, 2012

First Posted (ESTIMATE)

June 5, 2012

Study Record Updates

Last Update Posted (ESTIMATE)

December 2, 2015

Last Update Submitted That Met QC Criteria

November 30, 2015

Last Verified

November 1, 2015

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • R01DK082803 (NIH)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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