Habitual Diet and Avocado Trial (HAT)

The Habitual Diet and Avocado Trial will evaluate the effects of providing one avocado per day for recommended consumption over a 6 month period in a cohort of approximately 1000 free-living participants with increased waist circumference in comparison with a control group that will maintain their habitual diets. Participants will be recruited and screened at 4 clinics in 4 locations: Pennsylvania State University; Loma Linda University; UCLA, and Tufts University (250 per site).

Study Overview

• Status: Completed
• Conditions: Cardiovascular Diseases; Diabetes; Metabolic Syndrome; Liver Fat; Cardiovascular Risk Factor; Diet Habit; Dietary Modification; High Cholesterol; Triglycerides High; Low-density-lipoprotein-type; HDL Cholesterol, Low Serum; High Blood Sugar; Intra-abdominal Fat; High Density Lipoprotein Deficiency
• Intervention / Treatment: Other: Intervention Daily Avocado

Detailed Description

Preliminary evidence suggests that consumption of avocados can modulate body weight, food intake and markers of metabolic syndrome and may reduce visceral adiposity. Visceral adipose tissue is positively correlated with risk of cardiometabolic syndrome that predisposes to cardiovascular disease and diabetes. The Habitual Diet and Avocado Trial (HAT) aims to investigate an impactful outcome (visceral fat reduction) in a relevant population (Americans with an increased weight circumference) with a reasonable lifestyle modification (consumption of 1 avocado per day). HAT will evaluate the effect of providing one avocado per day for consumption over a 6 month period on established health parameters, including visceral adiposity, hepatic lipid content, markers of metabolic syndrome and high sensitivity C-reactive protein (hsCRP) when compared to a habitual diet. Blood specimens will be drawn and analyzed for fasting total cholesterol, triglyceride, HDL-C, glucose, insulin, hsCRP and RBC fatty acid profiles. Two non-contrast MRIs will be performed (at screening to assess eligibility and final participant visit 8 for randomized participants) to assess the volume of visceral adipose tissue and hepatic fat fraction. Four 24-hour dietary recalls will be conducted for study participants to capture dietary intake data. Questionnaires include the following: health and demographic including eating habits and physical activity; diet, food and avocado satisfaction (intervention group only); quality of life; and quality of sleep.

• Study Type: Interventional
• Enrollment (Actual): 1008
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Loma Linda, California, United States, 92354
      • Loma Linda University
    • Los Angeles, California, United States, 90095
      • University of California Los Angles (UCLA)
  • Massachusetts
    • Boston, Massachusetts, United States, 02111
      • Tufts University
  • Pennsylvania
    • University Park, Pennsylvania, United States, 16802
      • Pennysylvania State University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 25 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Increased waist circumference defined as ≥35 inches for women, ≥40 inches for men
• At least 25 years old at screening
• Not currently eating more than 2 avocados per month (habitual intake in U.S.)

Exclusion Criteria:

• Does not eat avocados
• Sensitive / allergic to avocados
• Allergies to latex or oral allergy syndrome
• Not willing or unable to undergo MRI scans
• Unstable medical condition such as on dialysis for renal disease, cardiac, gastrointestinal, or hepatic disease, cancer (non-melanoma skin cancer >5 years ago acceptable, any cancer site >10yrs without recurrence).
• Pregnant, lactating, intention of pregnancy
• Lost or gained 10 lbs of body weight in last year
• Following restricted or weight loss dietary patterns
• Unstable anti-anxiety / anti-depressive / anti-psychotic medication use defined as dose change within last 6 months
• Oral steroid use within the last 6 months longer than 7 days
• Elevated alcohol intake (7+ drinks/week females; 14+ drinks/week males)
• Participation in another clinical intervention trial within 30 days of baseline
• PI judgment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention Daily Avocado; Participants will follow their usual diet and lifestyle but also be provided with 1 avocado to consume per day for 6 months. To maximize compliance, participants will be provided with resources on how to choose, store and ripen avocados along with simple usage ideas. Specific nutrition guidance will not be provided. Participants will pick up fresh avocados every 2 weeks with minimal interaction with study personnel. Compliance visits will be conducted monthly.	Other: Intervention Daily Avocado; Participants follow their usual diet and lifestyle but also are provided with 1 avocado to consume per day for 6 months.
No Intervention: Control Usual Diet and Lifestyle; Participants will be instructed to follow their usual diet and lifestyle. Participants will be allowed to consume up to 2 avocados per month, but avocado consumption will not be encouraged and no avocados will be provided. Compliance visits will be conducted monthly.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Visceral adiposity	Non-contrast MRI scans will be performed to assess the volume of visceral adipose tissue. The outcome will be pre-post difference, compare the estimated mean change from baseline to follow-up in the 2 randomized groups with all tests of group differences performed according to the intent to treat.	Visit 1 (Screening, -2 to 0 weeks) and Visit 8 (26 weeks)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hepatic lipid content	Non-contrast MRI scans will be performed to assess hepatic lipid content/hepatic fat fraction.	Visit 1 (Screening, -2 to 0 weeks and Visit 8 (26 weeks)
Metabolic syndrome markers (serum triglycerides, serum cholesterol, fasting serum glucose, fasting insulin)	Phlebotomy is performed after a minimum 8 hour fast. Specimens will be separated and aliquoted, and shipped for analysis to Tufts University site for: fasting total cholesterol, triglyceride, high density lipo-protein cholesterol (HDL-C), glucose and insulin. LDL will be calculated using the Friedewald equation unless fasting triglyceride levels are > 400 mg/dL in which case they will be measured using a direct LDL assay. There will be a comparison of the estimated mean change from baseline to follow-up with all tests of group differences performed according to intent to treat.	Visit 2 (Baseline visit 0 weeks), Visit 5 (12 weeks), Visit 8 (26 weeks)
High-sensitivity C-reactive protein (hs-CRP)	C-reactive protein (CRP) is a protein that the liver makes when there is inflammation in the body. Also called a marker of inflammation and can be measured with the hs-CRP test. Inflamed arteries puts individuals at greater risk of heart disease, heart attack, stroke and peripheral arterial disease. A fasting sample will be obtained, shipped to and analyzed at Tufts University for hsCRP.	Visit 2 (baseline/randomization, Week 0), Visit 5 (12 weeks), Visit 8 (26 weeks)
Red blood cell (RBC) monounsaturated fat/polyunsaturated fat (MUFA/PUFA) ratio	Fasting RBC specimens shipped to Tufts University for analysis of RBC fatty acid profiles. The Fatty Acid Profile measures major fatty acids found in red blood cells.	Visit 2 (Baseline/Randomization Visit, 0 weeks), Visit 5 (12 weeks), Visit 8 (26 weeks)
Blood pressure	Seated blood pressure will be measured at each visit (except the screening visit) utilizing automated devices as per a standardized protocol across all sites. Three measurements will be taken after a 5 minute rest period, 1 minute apart. The last two readings are averaged for analysis.	Visit 2 (baseline/randomization 0 weeks) Visit 3 (4 weeks), Visit 4 (8 weeks), Visit 5 (12 weeks), Visit 6 (16 weeks), Visit 7 (10 weeks), Visit 8 (26 weeks)
Weight	Participants will be weighed at all in-study visits using high quality digital scales commonly used in clinical practice and that are in good working order. Participants will be weighed in light street clothes without shoes. The same scale is used throughout the trial.	Visit 2 (baseline/randomization), Visit 5 (12 weeks) and Visit 8 (26 weeks-final)
Waist circumference	A measuring tape specifically designed for waist circumference (recommended brands include Gulick or Seca) will be used according to a standardized procedure outlined in the trial Manual of Procedures. Waist circumference will be used during screening to assess eligibility. Measurements will be taken against the skin at the approximate midpoint between the lower margin of the last palpable rib and the top of the iliac crest. Two measurements are obtained at each visit and averaged.	Visit 1 (screening -2 to 0 weeks), Visit 2 (baseline/randomization 0 weeks), Visit 5 (12 weeks), Visit 8 (26 weeks)
Diet, Food and Avocado Satisfaction	Questions regarding participant satisfaction with the diet and food intervention will be assessed by completing the Diet, Food and Avocado Satisfaction Questionnaire. The questionnaire will only be completed by participants randomized to consume one avocado a day. The questionnaire is completed within 24 hours of a clinic visit and can be self- or staff administered. It consists of 14 questions about eating and preparing avocados each having a 100 point Likert scale with responses of "Not at all" and "Extremely".	Visit 2 (baseline/randomization, 0 weeks), Visit 5 (12 weeks), Visit 8 (26 weeks)
Quality of life RAND 36-Item Short Form Survey Instrument (SF-36)	All participants will complete the RAND (research and development) 36-Item Health Survey to assess 8 health concepts: physical functioning, bodily pain, role limitations due to personal or emotional problems, emotional well-being, social functioning, energy/fatigue and general health perceptions.All items are scored so that a high score defines more favorable health state. Each item is scored on a 0 to 100 range so that the lowest and highest possible scores are 0 and 100. Items in the same scale are averaged together to create 8 scale scores. Items that are left blank are not taken into account when calculating scale scores.	Visit 2 (baseline), Visit 5 (12 weeks) and Visit 8 (26 weeks-final)
Quality of Life RAND 20-Item Short Form Survey (SF-20)	The 20-item Short Form Health Survey (SF-20) was designed to reduce respondent burden while achieving minimum standards of precision for purposes of group comparisons involving multiple health dimensions. It includes 7 items to assess physical functioning, 2 items on role functioning, 1 social functioning survey item, 5 items to assess mental health, 4 items on current health perceptions and 1 item on pain. Participants in the control group will complete the RAND 20-Item Short Form Survey.	Visit 3 (4 weeks), Vist 4 (8 weeks) Visit 6 (16 weeks), Visit 7 (20 weeks)
Sleep quality	All participants will complete the Pittsburgh Sleep Quality Index questionnaire (PSQI) which is a self-rated questionnaire that assesses sleep quality and disturbances over a 1-month time time interval. 19 individual items generate seven "component" scores: subjective sleep quality; sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. The sum of scores for the 7 components yield one global score.	Visit 2 (baseline), Visit 5 (12 weeks) and Visit 8 (26 weeks-final)
24-hour diet recall	Four 24-hour dietary recalls will be conducted for each study participant during the course of the study. The goal for the 3 intra-study recalls is to capture intake data for 2 weekdays and 1 weekend day for each participant. The recalls are collected and analyzed using Nutrition Data System for Research (NDSR) software Vs 2017. The Loma Linda University site and Tufts University will be responsible for collecting 50% each of the 24 hour recalls across all study sites. They will follow a standardized manual of procedures for dietary data collection and dietary data management. Outcome data from NDSR will include daily estimated energy and nutrient intake, as well as food, food group and dietary supplement data.	Visit 1 (screening, -2 to 0 weeks), Visit 4 (8 weeks), visit 6 (16 weeks), Visit 8 (26 weeks)

Collaborators and Investigators

• Sponsor: Wake Forest University Health Sciences
• Investigators: Principal Investigator: David Reboussin, PhD, Wake Forest University Health Sciences

Publications and helpful links

General Publications

• Berryman CE, West SG, Fleming JA, Bordi PL, Kris-Etherton PM. Effects of daily almond consumption on cardiometabolic risk and abdominal adiposity in healthy adults with elevated LDL-cholesterol: a randomized controlled trial. J Am Heart Assoc. 2015 Jan 5;4(1):e000993. doi: 10.1161/JAHA.114.000993.
• Bertoli S, Leone A, Vignati L, Bedogni G, Martinez-Gonzalez MA, Bes-Rastrollo M, Spadafranca A, Vanzulli A, Battezzati A. Adherence to the Mediterranean diet is inversely associated with visceral abdominal tissue in Caucasian subjects. Clin Nutr. 2015 Dec;34(6):1266-72. doi: 10.1016/j.clnu.2015.10.003. Epub 2015 Oct 20.
• Cespedes Feliciano EM, Tinker L, Manson JE, Allison M, Rohan T, Zaslavsky O, Waring ME, Asao K, Garcia L, Rosal M, Neuhouser ML. Change in Dietary Patterns and Change in Waist Circumference and DXA Trunk Fat Among Postmenopausal Women. Obesity (Silver Spring). 2016 Oct;24(10):2176-84. doi: 10.1002/oby.21589. Epub 2016 Aug 22.
• Dhillon J, Tan SY, Mattes RD. Almond Consumption during Energy Restriction Lowers Truncal Fat and Blood Pressure in Compliant Overweight or Obese Adults. J Nutr. 2016 Dec;146(12):2513-2519. doi: 10.3945/jn.116.238444. Epub 2016 Nov 2.
• Estruch R, Martinez-Gonzalez MA, Corella D, Salas-Salvado J, Ruiz-Gutierrez V, Covas MI, Fiol M, Gomez-Gracia E, Lopez-Sabater MC, Vinyoles E, Aros F, Conde M, Lahoz C, Lapetra J, Saez G, Ros E; PREDIMED Study Investigators. Effects of a Mediterranean-style diet on cardiovascular risk factors: a randomized trial. Ann Intern Med. 2006 Jul 4;145(1):1-11. doi: 10.7326/0003-4819-145-1-200607040-00004. Erratum In: Ann Intern Med. 2018 Aug 21;169(4):270-271.
• Gower BA, Goss AM. A lower-carbohydrate, higher-fat diet reduces abdominal and intermuscular fat and increases insulin sensitivity in adults at risk of type 2 diabetes. J Nutr. 2015 Jan;145(1):177S-83S. doi: 10.3945/jn.114.195065. Epub 2014 Dec 3.
• Paniagua JA, Gallego de la Sacristana A, Romero I, Vidal-Puig A, Latre JM, Sanchez E, Perez-Martinez P, Lopez-Miranda J, Perez-Jimenez F. Monounsaturated fat-rich diet prevents central body fat distribution and decreases postprandial adiponectin expression induced by a carbohydrate-rich diet in insulin-resistant subjects. Diabetes Care. 2007 Jul;30(7):1717-23. doi: 10.2337/dc06-2220. Epub 2007 Mar 23.
• Ross R, Rissanen J, Pedwell H, Clifford J, Shragge P. Influence of diet and exercise on skeletal muscle and visceral adipose tissue in men. J Appl Physiol (1985). 1996 Dec;81(6):2445-55. doi: 10.1152/jappl.1996.81.6.2445.
• National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report. Circulation. 2002 Dec 17;106(25):3143-421. No abstract available.
• Wien M, Haddad E, Oda K, Sabate J. A randomized 3x3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults. Nutr J. 2013 Nov 27;12:155. doi: 10.1186/1475-2891-12-155.
• O'Neil, et al. Avocado consumption by adults is associated with better nutrient intake, diet quality and some measures of adiposity: NHANES Survey, 2001-2012. Int Med Rev In press.
• Lichtenstein AH, Kris-Etherton PM, Petersen KS, Matthan NR, Barnes S, Vitolins MZ, Li Z, Sabate J, Rajaram S, Chowdhury S, Davis KM, Galluccio J, Gilhooly CH, Legro RS, Li J, Lovato L, Perdue LH, Petty G, Rasmussen AM, Segovia-Siapco G, Sirirat R, Sun A, Reboussin DM. Effect of Incorporating 1 Avocado Per Day Versus Habitual Diet on Visceral Adiposity: A Randomized Trial. J Am Heart Assoc. 2022 Jul 19;11(14):e025657. doi: 10.1161/JAHA.122.025657. Epub 2022 Jul 5.

Study record dates

Study Major Dates

• Study Start (Actual): June 19, 2018
• Primary Completion (Actual): October 16, 2020
• Study Completion (Actual): October 30, 2020

Study Registration Dates

• First Submitted: May 4, 2018
• First Submitted That Met QC Criteria: May 4, 2018
• First Posted (Actual): May 17, 2018

Study Record Updates

• Last Update Posted (Actual): March 22, 2023
• Last Update Submitted That Met QC Criteria: March 17, 2023
• Last Verified: June 1, 2021

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Genetic Diseases, Inborn; Insulin Resistance; Hyperinsulinism; Metabolism, Inborn Errors; Lipid Metabolism Disorders; Hyperlipidemias; Dyslipidemias; Lipid Metabolism, Inborn Errors; Hyperglycemia; Cardiovascular Diseases; Metabolic Syndrome; Hypercholesterolemia; Hypoalphalipoproteinemias; Hypolipoproteinemias
• Other Study ID Numbers: IRB00047011

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Investigators may wish to perform ancillary studies using the HAT population, samples or other collected data. All ancillary studies must be approved by the HAT Steering Committee before being allowed access to study participant, samples or the database. De-identified individual participant data for all primary and secondary outcome measures will be made available to participating sites and for at the end of the study and for public use databases.
• IPD Sharing Time Frame: Data will be available within 6 months of study completion.
• IPD Sharing Access Criteria: Data access requests will be reviewed by the Steering Committee. Requestors will be required to sign a Data Access Agreement.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No