Daily avocado intake over 12 weeks improved the ability to focus attention and increased concentrations of lutein among adults with overweight and obesity, a new study by University of Illinois at Urbana-Champaign and Eastern Illinois University researchers has found.
Edwards et al evaluated the influence of avocado consumption on cognitive function and lutein status among adults with overweight and obesity using a randomized-controlled trial with matching design for pertinent study outcomes. Image credit: Sandid.
“Avocados are high in lutein, a dietary component associated with cognitive benefits,” said study first author Caitlyn Edwards, a graduate student in the Division of Nutritional Sciences at the University of Illinois at Urbana-Champaign.
“Though avocado consumption’s benefits have been studied in older adults and children, no randomized controlled trials had studied its cognitive effects on adults with overweight or obesity, despite 70% of the American adult population falling into that category.”
“Previous work has shown that individuals with overweight and obesity are at higher risk for cognitive decline and dementia in older age,” said study senior author Professor Naiman Khan, a scientist in the Division of Nutritional Sciences and the Department of Kinesiology and Community Health at the University of Illinois at Urbana-Champaign.
“We are interested in whether dietary approaches may have benefits for cognitive health, especially in midlife.”
In the study, the researchers provided 12 weeks of daily meals to 84 adults (25-45 years, 31 males) with overweight or obesity.
The meals were identical in calories and macronutrients, but one group’s meals included a fresh Hass avocado every day, while the control group had no avocado in their meals.
At the beginning and end of the study, the participants completed three cognitive tests to measure attention and inhibition.
In addition, the study authors measured lutein levels in the participants’ serum and in their retinas, which is associated with the lutein concentration in the brain.
They found that the participants whose diets included avocados improved their performance on one of the cognitive tests, called the Flanker task, which measures attentional inhibition — the ability to maintain focus on the task at hand even in the face of distraction.
However, there was no difference in the other two cognitive tests.
“It could be that nutrients in avocados have a specific action in the brain that supports the ability to do this task in particular, or they could be more beneficial for certain cognitive abilities over others,” Professor Khan said.
“It’s also possible that with a longer study or different tests, we could see other effects. Other studies have found broader effects in other populations, so it is interesting to see a more specific benefit for this population.”
Another unexpected finding was that, while the participants who ate avocados had higher levels of lutein at the end of the study, the changes in lutein levels were not correlated with their cognitive changes.
“Avocados also are high in fiber and monounsaturated fats. It is possible that these other nutrients may have played a role in the cognitive effects we saw, but we focused on the lutein in our analyses,” Edwards said.
“Future analyses may focus on other nutrients found in avocados, or avocado consumption’s impact on other measures such as weight status, inflammation and potential changes in the microbiome.”
The findings appear in the International Journal of Psychophysiology.
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Caitlyn G. Edwards et al. 2020. Effects of 12-week avocado consumption on cognitive function among adults with overweight and obesity. International Journal of Psychophysiology 148: 13-24; doi: 10.1016/j.ijpsycho.2019.12.006
