Replacing Refined Carbohydrates With Healthy Fats on Cardio-metabolic Markers (AV2)

Effects of a Typical American Diet High in Refined Carbohydrates Compared to a Diet That Replaces Some Refined Carbohydrates With Healthy Fats on Cardiometabolic Health in Men and Women With Pre-diabetes and Metabolic Syndrome

The primary goal is to to characterize the effects of consuming 1 avocado fruit 7 days / week (5-7 days is acceptable) compared to a no avocado relatively low fat, carbohydrate control treatment over a 12 week period on insulin sensitivity as measured by the Matsuda composite index of insulin sensitivity (MISI).

Study Overview

• Status: Completed
• Conditions: Metabolic Syndrome; Pre-diabetes
• Intervention / Treatment: Dietary supplement: Active; Dietary supplement: Control

Detailed Description

The trial is designed as a randomized, controlled, statistician blinded, 2-arm parallel study to investigate the effects of avocado consumption compared to non-avocado control foods which have opposing macronutrients (avocado is relatively higher in fat and in low carbohydrate and the control foods will be low fat, high carbohydrate options) on indices of cardiometabolic health over a 12 week period.

The trial will test 2 treatment conditions in pre-diabetic men and women 25-60 years of age with metabolic syndrome. One hundred twenty men and women will be recruited, aiming for a completer set of 96 subjects. Qualified Subjects will be randomized to receive 1 of 2 test treatments based on randomization schedule from a computer generated randomization schedule.

Study treatments include:

• Control (CT) diet plan with at least 1 serving of a low fat, low fiber, high glycemic carbohydrate and eliminate avocado 7 days / week (5-7 days is acceptable) over a 12 week period.
• Active treatment (AT) diet plan will include 1 Avocado 7 days/week (5-7 days is acceptable) over a 12 week period.

Each subject will be asked to come for one Screening Visit, 9 interim food pick-up/compliance visits and 4 Test Day Visits. The four main Test Day visits will occur at week 0 (day 1; baseline), end of week 4, at the end of week 8 and at the end of week 12. Interim Visits will occur at week 1, 2, 3, 5, 6, 7, 9, 10 and 11. Subjects will pick-up study foods, answer questionnaires, receive dietary counseling, confirm diet compliance during interim visits. They will also be asked to complete online 24 hour food recalls up to once per each week of the study. Each of the 4 Test Day Visits will last about 2-3.5 h and involve blood pressure (BP) measurements, a fasting blood sample collection and anthropometric, body composition assessment. In addition, an oral glucose tolerance test (OGTT) will be performed at week 0/day 1 and at the end of week 12/day.

• Study Type: Interventional
• Enrollment (Actual): 124
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60616
      • Clinical Nutrition Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 25 years to 60 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Men and women aged 25-65 yrs.
• BMI of 25 - 42 kg/m2
• HOMA-IR ≥ 2
• Abdominal obesity: mid-point waist circumference >102 cm for men and >88 cm for women
• No clinical evidence / history of heart disease, respiratory, renal, gastrointestinal, or hepatic disease
• Not taking over-the-counter or prescription medications/dietary supplements that may interfere with study procedures or endpoints (e.g., antioxidant supplements, protein powder, energy drinks, anti-inflammatory or lipid-lowering medications).
• Non-smoker or past smoker (smoking cessation > 2 yrs.)
• Able to provide informed consent and comply with study procedures

Exclusion Criteria:

• Aged < 25 or > 65 years
• BMI < 25 kg/m2 or > 42 kg/m2
• HOMA-IR < 2.0
• History of heart disease, respiratory, renal, gastrointestinal or hepatic disease
• Diabetes
• Have or had cancer other than non-melanoma skin cancer in past 5 years
• Taking over-the-counter or prescription medications or dietary supplements that may interfere with study procedures or endpoints (including protein powers, energy drinks)
• Vegan dietary habits, unusual dietary habits or sensitive or allergic to any of the test meal components / ingredients
• Consuming 3 or more avocados per week.
• Consuming 3 or more servings of nuts or peanuts per week, unless subject is willing to stop consuming nuts 4 weeks before and throughout the course of the study.
• Excessive coffee and tea consumers (>4 cups/day)
• Current smoker
• Actively losing weight or trying to lose weight (unstable body weight fluctuations of > 5 kg in 3 months
• Drug or alcohol addiction
• Present with significant psychiatric or neurological disturbances
• Working overnight (e.g 3rd shift of overnight workers)
• Pregnant, lactating or planning to become pregnant
• Have donated blood within 3 months of the screening visit and blood donors/participants for whom participation in this study will result in having donated more than 1500 milliliters of blood in the previous 12 months.
• Women who are taking unstable dose and brand of hormonal contraceptive and/or stable dose and brand less than 6 months
• Excessive exercisers or trained athletes
• Take part in chronic feeding or medication clinical trial in the last 3 months

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Active treatment (AT) diet plan; 1 Avocado 7 days/week (5-7 days is acceptable) over a 12 week period	Dietary supplement: Active; Active Treatment Diet Plan
Placebo Comparator: Control (CT) diet plan; at least 1 serving of a low fat, low fiber, high glycemic carbohydrate and eliminate avocado 7 days / week (5-7 days is acceptable) over a 12 week period	Dietary supplement: Control; Control Diet Plan

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in insulin sensitivity as measured by the Matsuda composite index of insulin sensitivity (MISI) in 12-week intervention of active treatment vs control treatment.	insulin sensitivity as measured by the Matsuda composite index	baseline and 12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in fasting blood glucose response in 12-week intervention of active treatment vs control treatment.	fasting blood glucose response in 12-week intervention	baseline and 12 weeks
Changes in fasting blood insulin response in 12-week intervention of active treatment vs control treatment.	fasting blood insulin response in 12-week intervention	baseline and 12 weeks
Changes in fasting HbA1c response in 12-week intervention of active treatment vs control treatment.	fasting HbA1c response in 12-week intervention	baseline and 12 weeks
Changes in blood pressure in 12-week intervention of active treatment vs control treatment.	blood pressure in 12-week intervention	baseline and 12 weeks
Changes in fasting blood Triglycerides concentration in 12-week intervention of active treatment vs control treatment.	fasting blood Triglycerides concentration in 12-week intervention	baseline and 12 weeks
Changes in fasting hs C-Reactive Protein in 12-week intervention of active treatment vs control treatment.	fasting hs C-Reactive Protein in 12-week intervention	baseline and 12 weeks
Changes in fasting markers of endothelial dysfunction (ICAM-1) in 12-week intervention of active treatment vs control treatment.	fasting markers of endothelial dysfunction (ICAM-1) in 12-week intervention	baseline and 12 weeks
Changes in fasting markers of endothelial dysfunction (VCAM-1) in 12-week intervention of active treatment vs control treatment.	fasting markers of endothelial dysfunction (VCAM-1) in 12-week intervention	baseline and 12 weeks
Changes in attitudes towards eating measured by the Stunkard 3-Factor Eating Questionnaire in 12-week intervention of active treatment vs control treatment.	attitudes towards eating measured by the Stunkard 3-Factor Eating Questionnaire in 12-week intervention	baseline and 12 weeks
Changes in plasma LDL cholesterol in 12-week intervention of active treatment vs control treatment.	plasma LDL cholesterol in 12-week intervention	baseline and 12 weeks
Changes in plasma total cholesterol in 12-week intervention of active treatment vs control treatment.	plasma total cholesterol in 12-week intervention	baseline and 12 weeks
Changes in plasma HDL cholesterol in 12-week intervention of active treatment vs control treatment.	plasma HDL cholesterol in 12-week intervention	baseline and 12 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in body weight in 12-week intervention of active treatment vs control treatment.	body weight in 12-week intervention	baseline and 12 weeks
Changes in waist circumference in 12-week intervention of active treatment vs control treatment.	waist circumference in 12-week intervention	baseline and 12 weeks
Changes in body composition in 12-week intervention of active treatment vs control treatment.	body composition in 12-week intervention	baseline and 12 weeks
Changes in blood lipoproteins in 12-week intervention of active treatment vs control treatment.	Changes in lipoprotein particle size/density by nuclear magnetic resonance (NMR)	baseline and 12 weeks
Changes in blood IL-6 in 12-week intervention of active treatment vs control treatment.	blood IL-6 in 12-week intervention	baseline and 12 weeks
Changes in blood MCP-1 in 12-week intervention of active treatment vs control treatment.	blood MCP-1 in 12-week intervention	baseline and 12 weeks

Collaborators and Investigators

• Sponsor: Clinical Nutrition Research Center, Illinois Institute of Technology
• Investigators: Principal Investigator: Britt Britt Burton-Freeman, Ph.D, Illinois Institute of Technology

Publications and helpful links

General Publications

• Zhang X, Xiao D, Guzman G, Edirisinghe I, Burton-Freeman B. Avocado Consumption for 12 Weeks and Cardiometabolic Risk Factors: A Randomized Controlled Trial in Adults with Overweight or Obesity and Insulin Resistance. J Nutr. 2022 Aug 9;152(8):1851-1861. doi: 10.1093/jn/nxac126.

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2016
• Primary Completion (Actual): January 20, 2021
• Study Completion (Actual): May 15, 2021

Study Registration Dates

• First Submitted: February 22, 2016
• First Submitted That Met QC Criteria: February 24, 2016
• First Posted (Estimate): March 1, 2016

Study Record Updates

• Last Update Posted (Actual): June 29, 2021
• Last Update Submitted That Met QC Criteria: June 25, 2021
• Last Verified: June 1, 2021

More Information

Terms related to this study

• Keywords: Inflammation; Metabolic syndrome; HbA1c; Lipid; Pre-diabetes; Blood glucose; Insulin response; Matsuda composite index of insulin sensitivity (MISI)
• Additional Relevant MeSH Terms: Pathologic Processes; Glucose Metabolism Disorders; Metabolic Diseases; Endocrine System Diseases; Disease; Diabetes Mellitus; Insulin Resistance; Hyperinsulinism; Hyperglycemia; Syndrome; Metabolic Syndrome; Prediabetic State; Glucose Intolerance
• Other Study ID Numbers: IRB2016-001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO