Development of a Novel Method to Study in Vivo Fatty Acid Metabolism Using Stable Isotope Labeled Fatty Acids in Humans

Development of a Novel Method to Study in Vivo Fatty Acid Metabolism Using Stable Isotope Labeled Fatty Acids in Humans.

Specific Aim 1: To compare the metabolic fate (transport, conversion and oxidation) of labeled 18:0 (13C18:0) and its metabolic product 18:1 (13C18:1) in the fed state after habituation to diets enriched in the corresponding fatty acid.

Hypothesis: In the fed state, the metabolic fate of 13C18:0 compared to 13C18:1 will be characterized by similar transport, higher conversion, and similar oxidation rates..

Study Overview

• Status: Completed
• Conditions: Dyslipidemia
• Intervention / Treatment: Other: Oleic Diet; Other: Palmitic Diet; Other: Stearic Diet

Detailed Description

Vegetable oils high in the specific fatty acids of interest - stearic (found in cocoa butter, meats), palmitic (found in meats, dairy and some plant oils) and stearic acid's metabolic product, oleic (found in olive and corn oil) - will be used to displace each other in a standardized diet and fed to mildly hypercholesterolemic postmenopausal women using a randomized-controlled crossover design. Six women who are enrolled in 10150 - Study A will be invited to participate in this study. Each of the phases will be 5 weeks in length with a 2-4 week break between phases. All food and drink will be provided to study volunteers. Blood pressure and body weight will be monitored once per week and adjustments made, if necessary, to maintain a stable weight. During week 1 of the 18:0 and 18:1 dietary phases, a fasting blood sample will be drawn. A single stool sample will be collected on any of the study visits after week three. On Day 1 of week 5, following a 12 hour fast, each volunteer will receive their usual diet divided into 15 hourly small meals. A purified tracer dose (1 mg/kg bodyweight [BW]) of 13C fatty acid will be incorporated into the 1pm meal. Blood samples will be collected from a catheter inserted into the subcubital vein just before consuming the first hourly meal and then 2, 5, 7, 8, 9, 11, 13 and 15 hours thereafter. Breath samples will be collected before the first hourly meal as well as at various time-points after. Additional fasting blood samples will be collected on Days 2, 3, 4 and 5 of the 18:0 and 18:1 diet phases. At the end of Day 1, volunteers will have the option of returning home or staying overnight at the Jean Mayer Human Nutrition Research Center.

• Study Type: Interventional
• Enrollment (Actual): 6
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02111
      • Jean Mayer Human Nutrition Research Center on Aging

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Postmenopausal women (menopause defined by complete natural cessation of menses for >12 months or a bilateral oophorectomy).
• Age >50 to < 85 years
• BMI >20 to <35 kg/m2
• LDL-cholesterol >100 mg/dL
• CRP (C reactive protein) <10 ug/dL
• Normal fasting plasma glucose levels (<120 mg/dL)
• Not taking medication known to affect lipid metabolism:

HMG-CoA reductase inhibitors (statins)

• Bile Acid Sequestrants (Cholestyramine, Colestipol, Colesevelam, etc.)
• Cholesterol Absorption Inhibitors (Ezetimibe [Zetia])
• Nicotinic Acid Agents (Niacin, Niacor, Slo-Niacin, etc)
• Fibrates (Gemfibrozil, Clofibrate, Ciprofibrate, Fenofibrate [Tricor], etc)
• Probucol
• Anticoagulants (Coumadin, Heparin, Plavix, etc)
• Hormone therapy medications containing estrogen
• Acetylsalicylic acid containing medications, aspirin
• Diphenylhydantoin
• Supplements containing fatty acids (Fish Oil, Flaxseed, etc.) and any other compounds that affect lipid metabolism (red yeast rice, etc.) for at least 3 months prior to participation in the study
• Anabolic steroids

• Hydrocortisone

  • Normal kidney function as assessed by serum creatinine and blood urea nitrogen
  • Normal liver function as assessed by serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase and alkaline phosphatase
  • Normal thyroid function as assessed by serum TSH (thyroid stimulating hormone)
  • Normal gastrointestinal function
  • Normotensive on or off medication
  • Non-smoker for at least 2 years
  • Alcohol intake < 7 drinks per week, and willingness to abstain from consuming alcohol while participating in the study.
  • Consistent physical activity
  • Willingness to follow protocol as detailed in the Institutional Review Board (IRB) approved consent form.

Exclusion Criteria:

• Men
• Women who have had a double mastectomy
• Age < 50 and > 85 years
• BMI < 20 and > 35 kg/m2
• LDL-cholesterol <100 mg/dL
• CRP > 10 ug/dL
• Abnormal fasting plasma glucose levels >120 mg/dL

• Use of medications known to affect lipid metabolism:

  • HMG-CoA reductase inhibitors (statins)
  • Bile Acid Sequestrants (Cholestyramine, Colestipol, Colesevelam, etc.)
  • Cholesterol Absorption Inhibitors (Ezetimibe [Zetia])
  • Nicotinic Acid Agents (Niacin, Niacor, Slo-Niacin, etc)
  • Fibrates (Gemfibrozil, Clofibrate, Ciprofibrate, Fenofibrate [Tricor], etc)
  • Anticoagulants (Coumadin, Heparin, Plavix, etc)
  • Hormone therapy medications containing estrogen
  • Probucol
  • Acetylsalicylic acid containing medications, aspirin
  • Diphenylhydantoin
  • Supplements containing fatty acids (Fish Oil, Flaxseed, etc.) and any other compounds that affect lipid metabolism (red yeast rice, etc.) in the last 3 months prior to participation in the study
  • Anabolic steroids and hydrocortisone
• Renal or kidney disease, as defined by a history of chronic kidney disease or by glomerular filtration rate of < 60 ml.min/1.73 m2 calculated from screening blood tests.
• Hypothyroidism or hyperthyroidism, as defined as screening TSH outside of normal ranges (<0.4 or >4.5), unless controlled with medication for at least 6 months
• Gastrointestinal disease
• Uncontrolled hypertension or high BP reading at the discretion of the study physician or nurse
• Established cardiovascular disease as defined by history of myocardial infarction, stroke, heart failure, coronary artery bypass graft, stenosis >50%, angina and peripheral arterial disease)
• Anemia, as defined by screening haemoglobin <11.7g/dL.
• Liver disease, as defined by a history of chronic hepatitis B or C, cholestatic or cirrhotic liver disease, nonalcoholic fatty liver disease, elevations of SGPT or SGOT greater than 1.5 times the upper limit of normal at screening, bilirubin greater than 2 mg/dL (in the absence of benign causes of elevated bilirubin such as Gilbert's syndrome) at screening, or albumin below the lower limit of normal.
• Type I and II diabetes
• Any non-steroidal anti-inflammatory drugs (NSAID) or antihistamine use by subject for 72 hours prior to blood draws
• Smoking or use of nicotine-containing products within the past 2 years
• Alcohol intake > 7 drinks per week or unwillingness to abstain from consuming alcohol while participating in the study
• Unwillingness to maintain body weight during participation in the study
• Unwillingness to adhere to diet and study protocol
• Weight gain or loss of more than 15 lb within 6 months prior to enrollment
• Vegetarians and those with food allergies or aversions
• Non-English speaking subjects
• No Social Security number
• Women who have a history of difficulty with blood draws
• Blood donation within the past 8 weeks

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 18:1 diet; Oleic Diet - volunteers will consume oleic enriched food for a period of 5 weeks.	Other: Oleic Diet; The 18:1 (oleic) diet will contain 55%E carbohydrate, 15%E protein, 30%E fat, 100 mg cholesterol/1000 kcal and 15 g fiber/1000 kcal. The vegetable oils and/or fats (henceforth collectively referred to as experimental oils) that will be used to formulate the diets were selected not only take into account the fatty acid of interest but also the fatty acid displaced within the context of an unchanged total fat content. This was accomplished by formulating a diet containing 10%E fat and then adding the experimental oils (oleic) to 30%E total fat by incorporating them into various food items intended for consumption throughout the day. The actual food items comprising the 3 diets will be similar, only differing in the experimental oils.; Other Names: Diet enriched in oleic acid; 18:1
Experimental: 16:0 diet; Palmitic diet - Volunteers will consume palmitic enriched food for a period of 5 weeks.	Other: Palmitic Diet; The 16:0 (palmitic) diet will contain 55%E carbohydrate, 15%E protein, 30%E fat, 100 mg cholesterol/1000 kcal and 15 g fiber/1000 kcal. The vegetable oils and/or fats (henceforth collectively referred to as experimental oils) that will be used to formulate the diets were selected not only take into account the fatty acid of interest but also the fatty acid displaced within the context of an unchanged total fat content. This was accomplished by formulating a diet containing 10%E fat and then adding the experimental oils (palmitic) to 30%E total fat by incorporating them into various food items intended for consumption throughout the day. The actual food items comprising the 3 diets will be similar, only differing in the experimental oils.; Other Names: Diet enriched in palmitic acid.; 16:0
Experimental: 18:0; Stearic Diet - Volunteers will receive Stearic enriched food for a period of 5 weeks.	Other: Stearic Diet; The 18:0 diet (stearic) will contain 55%E carbohydrate, 15%E protein, 30%E fat, 100 mg cholesterol/1000 kcal and 15 g fiber/1000 kcal. The vegetable oils and/or fats (henceforth collectively referred to as experimental oils) that will be used to formulate the diets were selected not only take into account the fatty acid of interest but also the fatty acid displaced within the context of an unchanged total fat content. This was accomplished by formulating a diet containing 10%E fat and then adding the experimental oil (stearic) to 30%E total fat by incorporating them into various food items intended for consumption throughout the day. The actual food items comprising the 3 diets will be similar, only differing in the experimental oils.; Other Names: Stearic acid enriched diet.; 18:0

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
fatty acid kinetics in total plasma	measurement of isotope ratio (13C:12C) in total plasma, cholesterol ester, triglyceride, phospholipid, monoglyceride and diglyceride subfractions as well as chylomicrons, VLDL (very low density lipoprotein), TRL (triglyceride-rich lipoprotein), LDL (low density lipoprotein) and HDL (high density lipoprotein).	15 weeks
fatty acid kinetics in cholesterol ester		15 weeks
fatty acid kinetics in triglyceride		15 weeks
fatty acid kinetics in phospholipid		15 weeks
fatty acid kinetics in monoglyceride subfraction		15 weeks
fatty acid kinetics in diglyceride subfraction		15 weeks
fatty acid kinetics in chylomicrons		15 weeks
fatty acid kinetics in VLDL (very low density lipoprotein)		15 weeks
fatty acid kinetics in TRL (triglyceride-rich lipoprotein)		15 weeks
fatty acid kinetics in LDL (low density lipoprotein)		15 weeks
fatty acid kinetics in HDL (high density lipoprotein)		15 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
rate of oxidation	breath analysis will be conducted to determine rate of oxidation	15 weeks

Collaborators and Investigators

• Sponsor: Tufts University
• Investigators: Principal Investigator: Alice H Lichtenstein, D.Sc., Tufts University/HNRCA

Study record dates

Study Major Dates

• Study Start: January 1, 2013
• Primary Completion (Actual): June 1, 2016
• Study Completion (Actual): December 1, 2018

Study Registration Dates

• First Submitted: June 4, 2014
• First Submitted That Met QC Criteria: December 5, 2014
• First Posted (Estimate): December 9, 2014

Study Record Updates

• Last Update Posted (Actual): April 18, 2019
• Last Update Submitted That Met QC Criteria: April 17, 2019
• Last Verified: April 1, 2019

More Information

Terms related to this study

• Keywords: fatty acid kinetics
• Additional Relevant MeSH Terms: Metabolic Diseases; Lipid Metabolism Disorders; Dyslipidemias; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Palmitic Acid
• Other Study ID Numbers: 1542 - Fatty Acid Kinetics