Cognitive function, including complex executive functions like working memory and basic functions like sensory processing, progressively declines with age. While executive function loss is highly variable and easily measurable in older adult populations, younger adults usually perform at a level consistent with their peers, which makes studying cognitive decline in younger adults difficult. In a 2014 report, researchers measured visual processing ability in young adults before and after supplementation with lutein and zeaxanthin.

Visual processing refers to the brain’s ability to utilize and interpret visual information. Because visual processing utilizes similar brain architecture as more complex tasks such as working memory, it is a useful measure in assessing brain health and cognitive decline.

Lutein and zeaxanthin are carotenoid pigments found in foods that accumulate in the retina and throughout the brain and perform light-absorbing, antioxidant, and anti-inflammatory functions. Animal research has demonstrated that the density of these pigments in the eye is a good indicator of their density in the brain, providing researchers a non-invasive means to measure the relationship between pigmentation and cognitive function. Higher pigment density in the eye[has been associated with better cognitive performance and visual processing speed in older adults with or without cognitive decline.

Researchers measured the baseline visual processing speed and retinal concentration of lutein and zeaxanthin in healthy young adults (average age, 22 years). They assigned participants to consume either placebo, zeaxanthin only (20 milligrams), or a combination of zeaxanthin (26 milligrams), lutein (8 milligrams), and mixed omega-3 fatty acids (190 milligrams) per day for four months. They measured retina pigmentation and visual processing speed again following the intervention.

The authors reported a moderate, yet statistically significant, relationship between baseline retinal pigment levels and visual processing speed. Following the intervention, both supplement groups demonstrated a significant increase in retinal pigmentation compared to placebo. Finally, participants in the supplement groups also performed 12 percent better on the critical flicker fusion test and decreased visual motor reaction time by 10 percent, two measures of visual processing.

The authors conclude that lutein and zeaxanthin supplementation may be an effective way to increase visual processing speed, even in young healthy adults.

Link to full study.