Funding for the research was provided by the Hass Avocado Board and the USDA National Institute of Food and Agriculture.
Avocados are high in “hearth-healthy” monounsaturated fats and dietary fiber which plays an important role in supporting gut health and the microbiome, said the study authors.
"We can't break down dietary fibers, but certain gut microbes can. When we consume dietary fiber, it's a win-win for gut microbes and for us," said Hannah Holscher, assistant professor of nutrition in the Department of Food Science and Human Nutrition at U of I and senior author of the study.
Past research has shown a link between regular avocado consumption and satiety as well as reduced blood cholesterol, but much less is known about how avocados may influence the gut microbes which break down fiber, said Sharon Thompson, graduate student in the Division of Nutritional Sciences at U of I and lead author on the paper, published in the Journal of Nutrition.
"The purpose of this study was to explore the effects of avocado consumption on the gastrointestinal microbiota," said Holscher.
"Our goal was to test the hypothesis that the fats and the fiber in avocados positively affect the gut microbiota. We also wanted to explore the relationships between gut microbes and health outcomes," said Holscher.
Study methods and results
The study included 163 adults between 25 and 45 years of age who were either overweight or obese – defined as a BMI of at least 25 – but otherwise healthy. Study participants received one meal per day to consume as a replacement for either breakfast, lunch, or dinner. One group consumed an avocado with each meal, while the control group consumed a similar meal but without the avocado.
The participants provided blood, urine, and fecal samples throughout the 12-week study. They also reported how much of the provided meals they consumed, and every four weeks recorded everything they ate. Participants were not advised to restrict or change anything else they ate through the 12-week period, noted researchers.
Researchers found that daily avocado consumption resulted in increased fecal acetate levels (the most prevalent microbial fermentation product), enriched levels of Faecalibacterium, Lachnospira, and Alistipes (the bacteria capable of fiber fermentation), and increased concentrations of microbially derived metabolites in the fecal samples of the avocado group.
“Fresh Hass avocado intake over a 12-week period resulted in changes to the fecal microbiota and increased concentrations of microbially derived metabolites among adults with overweight and obesity. The fecal bile acid pool was diminished, and relations were observed between fecal bacteria and metabolic biomarkers. These findings provide valuable insight regarding the impact of avocado intake on the intestinal microbiota and have important implications for dietary interventions conducted among the growing at-risk population of adults with overweight or obesity,” wrote researchers.
While already considered a nutrient-dense food that provides important micronutrients such as potassium, fiber, and “healthy” fats, the research provides strong evidence that avocadoes could be considered a gut-healthy food as well, claimed Holscher.
“Our work shows we can add benefits to gut health to that list... Just like we think about heart-healthy meals, we need to also be thinking about gut healthy meals and how to feed the microbiota."