Visual processing: lutein, zeaxanthin and Omega-3 improve it

Intake of zeaxanthin, alone or combined with lutein and Omega 3, enhances visual processing speed by about 10 percent compared with placebo, in healthy young subjects. It would thus appear that the two carotenoids not only contribute to eye health, but are also able to act in the areas of the brain involved in vision.

This is shown by data published in the journal PLoS One by researchers, led by Dr. Hammond, of the University of Georgia (USA).

Two molecules important for vision

Lutein and zeaxanthin are molecules belonging to the carotenoid family.

Carotenoids are a group of pigments that are widespread in nature.

The importance of lutein and zeaxanthin for humans is due to the fact that they are highly concentrated in the macula, the central area of the retina, which is the region of the eye that converts visual impulses into nerve impulses.

Back in 1994, Dr. Johanna Seddon, and her collaborators at Harvard University, found a link between the intake of carotenoid-rich foods, such as green leafy vegetables, and a significant reduction in the risk of age-related macular degeneration.

These were followed by numerous studies on primates, children, middle-aged and elderly people to support the importance of lutein in eye and brain health.

It has been hypothesized that these pigments may influence post-retinal visual signal processing.

Much of the research on this has been conducted by Elizabeth Johnson, a scientist at the Nutrition Research Center on Aging at Tufts University in Boston.

His recent studies with children have shown that about 60 percent of the total carotenoids in pediatric brain tissue are lutein, but it accounts for only 12 percent of dietary carotenoid intake.

Zeaxanthin increases visual acuity

The new study included 64 healthy young subjects who were randomly divided into three groups.

For four months, one group received placebo, a second group received a daily dose of 20 mg of zeaxanthin, and the third group took a combination of 8 mg daily of lutein, 26 mg of zeaxanthin and 190 mg of Omega-3.

Data at the beginning of the study showed that people with higher pigment density in the macula (an indicator of lutein and zeaxanthin levels in the brain), had higher thresholds of Critical Flicker Fusion (CFF), that is, the minimum number of flashes of light per second in which the intermittent stimulus appears constant to the observer, and the ability to coordinate vision and body movements.

After treatment, specifi test results showed that those who had taken zeaxanthin in combination or not with lutein and Omega-3 had enhanced both CFF and visual-motor reaction time.

More precisely, the zeaxanthin-containing supplements had increased CFF threshold by about 12 percent, and visual-motor reaction time by about 10 percent, compared with placebo.

A more efficient nervous system 

The visual stimuli used in these experiments were specifically designed to test visual 'processing. Therefore, the mechanisms underlying the behavioral responses probably also reflect the functional properties of the brain and not just the optical or neural properties of the eye itself.

Indeed, CFF is associated with cognitive performance, suggesting that the relationships with lutein and zeaxanthin may reflect a mechanism related to neural processing speed.

Increasing macular pigment density through supplements resulted in significant improvements in visual processing speed even in healthy individuals who tend to be at peak efficiency.

Producing measurable changes in healthy young people is promising given the high practical and therapeutic relevance of a faster more efficient nervous system.

Source:  

E.R. Bovier, L.M. Renzi, B. R. Hammond "A Double-Blind, Placebo-Controlled Study on the Effects of Lutein and Zeaxanthin on Neural Processing Speed and Efficiency" PLoS One.Published online ahead of print, doi: 10.1371/journal.pone.0108178.