Carotenoids are plant pigments. They make tomatoes red and give carrots their distinctive orange hue. You see them when leaves change colors in the fall. But carotenoids are not just decorative.
Among the roughly 600 carotenoids in nature, two in particular, lutein and zeaxanthin, have been found to improve the function of the human brain, according to researchers at the University of Georgia.
”Carotenoids, in general, when we eat them, they are antioxidants, so they do a great job of keeping our bodies healthy and free of oxygenated damage,” says Lisa Renzi-Hammond, one of the researchers looking at the effect of lutein and zeaxanthin.
“They are anti-inflammatories, so we see that the more of these molecules we eat, the less inflammation we tend to have,’’ she says. “Our research shows that they are also changing, in many ways, the structure of the brain, and making it a more efficient organ.”
Lutein is a lipid, fat-based anti-oxidant that the brain uses to prevent the oxidation of the fat in the brain, says Billy Hammond, who is Renzi-Hammond’s research partner and husband. “It basically kind of links neurons together so they act more efficiently, so it helps cognition and a number of other processing things that the brain does.”
In an experiment, Hammond and Renzi-Hammond looked at increased lutein intake in both older adults and people of college age. The study populations were given lutein and zeaxanthin supplements for a year to see how this changed their cognition. The groups taking the supplements were compared to groups taking a placebo.
“We found that by improving basic functions, like helping the brain process faster, that all of the cognitive functions were improved as well, so they had better memory, better problem-solving, compared to a placebo,” says Hammond, “The [patients with] placebos didn’t improve, but the subjects that were supplemented with lutein and zeaxanthin did.”
The researchers found improvement in the older adults in the study, something they had expected. Older individuals have a wide range of cognitive functional abilities because of natural, age-related changes in the brain.
But the big surprise was the cognitive benefit seen in the college students. “Adding lutein in supplemental form to the diets of our younger adults really improved them,’’ Renzi-Hammond says.
The result with the students was unexpected because it had not seemed likely there was much room for improvement in the cognitive functions of people so young. ‘‘We sampled UGA students almost like a control to our older adult population,” says Renzi-Hammond, because young college students “shouldn’t be varying too much to each other in terms of cognitive function, . . . should all be pretty well performing at peak.”
“If you think about it,” says Hammond, “at no time in your life are you using your brain more than when you are a college student, you’re young — they are like 19 years old — studying all the time, so they were probably going to be the hardest group to see a change in.
“So the fact that we could see a change in them, too, was, I think, a pretty significant thing.”
Unfortunately, the kinds of food that many of us eat every day may be lacking in important carotenoids.
Unhealthy dietary patterns are associated with a lot of negative health outcomes. And one of these is a low level of lutein in the body.
She says that when looking at the retinas of the eyes, you are looking at a bit of brain tissue that has been pushed forward. The brain preferentially loads lutein, she says, and the retina loads lutein to the exclusion of everything else. So the retina is a great indicator of whether you are getting enough lutein.