Haas Avocado Intake Alters Fecal Microbiota and their Metabolites in Overweight and Obese Adults

by | Jan 26, 2021 | 2020, Digestive Health, Fruits and Vegetables, Obesity

Written by Joyce Smith, BS. This study evaluates the metabolic health benefits of avocado consumption and their effects on gastrointestinal microbiota in overweight and obese individuals.

fruits and vegetables- avocadoAvocados are a rich source of dietary fiber and monounsaturated fatty acids (MUFAs}, both of which are known to benefit health and the gastrointestinal microbiota. Studies have shown an association between obesity and an altered gastrointestinal microbiota; however, there is conflicting evidence as to how a diet rich in MUFAs affects the gut microbiota and their metabolites 1,2. When dietary carbohydrates and proteins are ingested, the gut microbes produce metabolites of volatile fatty acids that include short-chain fatty acids (SCFAs) and branched-chain fatty acids (BCFAs) 3. While considered generally beneficial, these metabolites are often more plentiful in overweight and obese individuals 4. Liver-produced bile salts that are released by the gall bladder to digest dietary fat, can alter or modify the gastrointestinal microbiota 5. Thus a high-fat western diet can increase bile acid concentrations 6, induce inflammation, and by altering gut microbiota, can also affect health and immunity 7. The following study was designed to explore whether avocado fats and fiber positively affect the gut microbiota and to ascertain potential relationships between gut microbiota and health outcomes.

The Persea Americana for Total Health (PATH) study 8 was a randomized controlled study of 163 overweight or obese adults, 25- 45 years of age. They were divided into two groups to receive fresh Hass as part of a meal or an isocaloric control meal (control group). Men received 175 grams and women 140 grams of avocado once per day for 12 weeks. All participants provided blood, urine, and fecal samples throughout the study. Their dietary intake was evaluated using 7-day diet records in which they recorded their daily food and beverage consumption. Height, weight and BMI were measured in triplicate. Fecal samples were collected and concentrations of SCFA metabolites (butyrate, propionate, and acetate) and BCFA metabolites (isobutyrate, valerate, and isovalerate) were quantified.

Participants who ate avocado every day as part of a meal had not only greater microbial diversity but also a greater abundance of gut microbes that break down fiber and produce metabolites that support gut health. At the end of 12 weeks, α-diversity did not differ between the two groups (P = 0.13); however, the relative abundances of Alistipes (P = 0.003) and Ruminococcus (P = 0.01) were greater and Faecalibacterium (P = 0.07) and Lachnospira tended to be more enriched (P = 0.06) in the avocado group compared to the control group. Fecal acetate concentrations were also higher in the avocado group (P=0.02) while fecal cholic acid and total bile acid concentrations were higher in the control group (P=0.01).

Avocados are rich in fiber, including soluble hemicelluloses and pectins that can be metabolized by intestinal microorganisms to produce SCFAs 9. Avocados are also rich in fat. Those who ate avocados excreted more fat in their stools suggesting that they were absorbing less energy from the foods they consumed. Bile acids that allow the body to digest and absorb fat, were lower in the stools of the avocado group, and their stools contained higher amounts of fat when compared to the control group. These insights may be useful considerations in formulating dietary interventions for our at-risk overweight and obese populations.

Study limitations include a potential self-reporting bias of meal intake, and a failure to diagnose any underlying health conditions that limit the generalizability of study results to individuals who are not overweight or obese or who have a chronic disease.

Source: Thompson, Sharon V., Melisa A. Bailey, Andrew M. Taylor, Jennifer L. Kaczmarek, Annemarie R. Mysonhimer, Caitlyn G. Edwards, Ginger E. Reeser, Nicholas A. Burd, Naiman A. Khan, and Hannah D. Holscher. “Avocado consumption alters gastrointestinal bacteria abundance and microbial metabolite concentrations among adults with overweight or obesity: a randomized controlled trial.” The Journal of Nutrition (2020).

©The Author(s) on behalf of the American Society for Nutrition 2020. This is an Open Access article distributed under the terms of the Creative CommonAttribution License (http://creativecommons.org/licenses/by/4.0/)

Click here to read the full text study.

Posted January 26, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

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