A diet including daily avocado consumption improves the ability to focus attention in adults whose measurements of height and weight are categorized as overweight or obese, say researchers. For the findings, published in the Journal of Psychophysiology, researchers at the University of Illinois in the US, conducted the 12-week study of daily meals to 84 adults with overweight or obesity.
"We are interested in whether dietary approaches may have benefits for cognitive health, especially in midlife," Khan added. Avocados are high in lutein, a dietary component associated with cognitive benefits. 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.
In the new study, the researchers provided 12 weeks of daily meals to 84 adults with overweight or obesity. The meals were identical in calories and macronutrients, but one group's meals included a fresh 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 researchers 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," 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," Khan added.
Although this study focused on avocados, other dietary sources of lutein, fiber and unsaturated fats - such as green leafy vegetables or eggs - also have potential cognitive and health benefits. The researchers said their study shows that small dietary changes, such as eating avocados, can have measurable impacts on cognitive performance, even when other health behaviors remain the same.