28 Aug 2017 --- Consuming one fresh avocado per day may lead to improved cognitive function in healthy older adults thanks to increased lutein levels in the brain and eye, according to new research published in the journal Nutrients. The research tracked how 40 healthy adults ages 50 and over who ate one fresh avocado a day for six months experienced a 25 percent increase in lutein levels in their eyes and significantly improved working memory and problem-solving skills.