The design and rationale of a multi-center randomized clinical trial comparing one avocado per day to usual diet: The Habitual Diet and Avocado Trial (HAT)

Authors: REBOUSSIN, DAVID - Wake Forest School Of Medicine; KRIS-ETHERTON, PENNY - Pennsylvania State University; LICHTENSTEIN, ALICE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; LI, ZHAOPING - University Of California (UCLA); SABATE, JOAN - Loma Linda University; MATTHAN, NIRUPA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; PETERSEN, KRISTINA - Texas Tech University; RAJARAM, SUJATHA - Loma Linda University; VITOLINS, MARA - Wake Forest School Of Medicine; FORD, NIKKI - Hass Avocado Board

Submitted to: Contemporary Clinical Trials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2021
Publication Date: 9/5/2021
Citation: Reboussin, D.M., Kris-Etherton, P.M., Lichtenstein, A.H., Li, Z., Sabate, J., Matthan, N., Petersen, K.S., Rajaram, S., Vitolins, M.Z., Ford, N. 2021. The design and rationale of a multi-center randomized clinical trial comparing one avocado per day to usual diet: The Habitual Diet and Avocado Trial (HAT). Contemporary Clinical Trials. 110: 106565. https://doi.org/10.1016/j.cct.2021.106565.
DOI: https://doi.org/10.1016/j.cct.2021.106565

Interpretive Summary: This manuscript describes the design of a multi-center human intervention trial to determine the effect of avocados consumption on body fat and chronic disease risk factors. Excess fat in the mid-section (visceral adiposity) is associated with elevated diabetes and heart disease risk. In the U.S. approximately 60% of adults have excess body fat in the mid-section. The Habitual Diet and Avocado Trial (HAT) was designed to determine if providing one avocado per day for six months compared to a habitual diet without avocados would reduce excess fat in the mid-section. To answer this question a multi-center, randomized, controlled trial was designed. Recruited was a large (~1,000) and diverse group of individuals that had a waist circumference higher than that classified as "healthy". Fat in the mid-section of participants was measured at the beginning and end of the study using an imaging technique known as magnetic resonance imaging (MRI). The technique allows for a visualization of body fat in different parts of the body. Additional measures of interest were liver lipid content, plasma lipid profiles, blood pressure and a marker of inflammation, high sensitivity C-reactive protein. Subjects were entered into the study if they had excess fat in the mid-section evaluated on the basis of waist circumference and not currently eating more than two avocados per month. Subjects were not eligible for participation if they do not like or have adverse reactions to avocados, and not willing or able to undergo MRI scans. HAT will provide information on the effects of avocado consumption on excess fat in the mid-section and cardiometabolic disease risk in a diverse sample of participants.

Technical Abstract: Excess visceral adiposity is associated with increased risk of diabetes and cardiovascular disease. In the U.S. approximately 60% of adults have visceral obesity. Despite high calorie and fat, small, well-controlled clinical studies suggest that avocado consumption has favorable effects on body weight and visceral adiposity. Additionally, short-term studies also suggest that consuming avocados increases satiety, hence, may decrease overall energy intake. The Habitual Diet and Avocado Trial HAT is a multi-center, randomized, controlled trial designed to test whether in a large, diverse cohort providing one avocado per day for consumption for six months compared to a habitual diet essentially devoid of avocados, will result in a decrease in visceral adiposity as measured by magnetic resonance imaging (MRI) in individuals with an increased waist circumference (WC). Additional outcome measures include hepatic lipid content, plasma lipid profiles, blood pressure and high sensitivity C-reactive protein. Inclusion criteria were increased WC and not currently eating more than two avocados per month. Major exclusion criteria were not eating or being allergic to avocados, and not willing or able to undergo MRI scans. From June 27, 2018 to March 4, 2020, 1008 participants were randomized at 4 clinics. The cohort was 72% women, 53% Non-Hispanic White, and had a mean age of 50 years. Follow-up was completed in October 2020 when 936 participants had final MRI scans. HAT will provide information on the effects of avocado consumption on visceral fat adiposity and cardiometabolic disease risk in a diverse sample of participants.