How much do lutein and zeaxanthin really do for eye and vision health?

The plant pigments lutein  and zeaxanthin have been shown to protect against macular degeneration. New research suggests that they may also support cognitive function by improving cerebral blood flow in older adults. There is a direct connection between the eye and the brain, and when doctors examine the retina and optic nerve, they are actually looking at brain cells indirectly. The retina is made up of certain plant pigments that are good indicators of visual health. Two of these pigments are carotenoids, called lutein and zeaxanthin. Supplementing with these carotenoids may help prevent age-related vision loss. A 2018 study showed that lutein and zeaxanthin may also improve cognitive function by improving cerebral blood flow. Even when these carotenoid supplements are taken at a relatively late age, brain function improves. This is exciting news because reduced cerebral blood flow is a contributing factor to neurodegenerative diseases. The carotenoids lutein and zeaxanthin are well known for their effectiveness in preventing age-related vision loss. Now, research suggests that they have additional benefits for the brain. A clinical study of older adults found that zeaxanthin and lutein may increase cerebral blood flow and protect the brain from the effects of aging.

Eye-Brain Connection

Carotenoids are yellow-orange pigments found in many vegetables. They were originally isolated from carrots, hence their name.

High intakes of carotenoids may protect against macular degeneration (an eye disease that can lead to blindness), cancer, cardiovascular disease, and neurodegenerative diseases. Two carotenoids in particular—lutein and zeaxanthin—are highly concentrated in the human retina. However, the more we learn about these nutrients, the more we realize that they are just as important for brain health as vision. This makes sense, since the retina is structurally an extension of the brain itself. In addition, lutein and zeaxanthin belong to a subclass of carotenoids, lutein, which was recently identified as the predominant carotenoid in all major brain regions. Based on these findings, researchers at the University of Georgia conducted the first randomized controlled trial to test whether supplementation with lutein and zeaxanthin could benefit cognitive function in older adults.

Lutein and Zeaxanthin Boost Brain Blood Flow

In this study, a group of older adults (average age 72) took either a placebo or a pill containing lutein (10 mg) and zeaxanthin (2 mg) daily for one year. The researchers used an advanced imaging technique called functional magnetic resonance imaging to observe in real time the brain activity of the subjects as they performed various tasks that require learning and memory. This technique provided the researchers with a unique opportunity to observe how brain regions "light up" during cognitive tasks, highlighting blood flow to each brain region and thus measuring how hard the brain is performing the current task.

Article Abstract

Lutein and zeaxanthin are widely recognized for their protective effects on vision in the macula of the retina. They have also been shown to support cognitive function and improve cerebral blood flow in older adults. These findings extend previous studies that have shown a strong correlation between high levels of lutein and zeaxanthin in the eye and improved cognitive function and protection of the brain's white matter. Lutein's unique biological structure allows it to cross brain cell membranes, protecting against oxidative stress generated inside and outside the cells. Even in late life, the effects of lutein and zeaxanthin on cognitive function and cerebral blood flow were evident, meaning that even for older adults, a window of opportunity to protect the brain still exists.