Visual Processing: Lutein, Zeaxanthin and Omega-3 Improve It

The intake of zeaxanthin, alone or combined with lutein and Omega 3, enhances visual processing speed by about 10% compared to placebo in young and healthy subjects. It appears that these two carotenoids not only contribute to eye health but also act in brain areas involved in vision.

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

Two Important Molecules for Vision

Lutein and zeaxanthin are molecules belonging to the carotenoid family.

Carotenoids are a group of pigments widely distributed in nature.

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

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

Numerous studies on primates, children, middle-aged, and elderly people have followed, supporting the importance of lutein in eye and brain health.

It has been hypothesized that these pigments can influence the processing of post-retinal visual signals.

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

Her recent studies with children demonstrated that about 60% of the total carotenoids in pediatric brain tissue is represented by lutein, even though it represents only 12% of dietary carotenoids intake.

Zeaxanthin Increases Visual Acuity

The new study included 64 young healthy subjects 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 per day of lutein, 26 mg of zeaxanthin, and 190 mg of Omega-3.

Baseline data showed that people with higher macular pigment density (an indicator of lutein and zeaxanthin levels in the brain) had higher thresholds of Critical Flicker Fusion (CFF), i.e., the minimum number of light flashes per second at which an intermittent stimulus appears steady to the observer, and better ability to coordinate vision and body movements.

After treatment, specific test results showed that those who had taken zeaxanthin, with or without lutein and Omega-3, enhanced both CFF and visuomotor reaction time.

More precisely, supplements containing zeaxanthin increased the CFF threshold by about 12% and visuomotor reaction time by about 10% compared to placebo.

A More Efficient Nervous System 

The visual stimuli used in these experiments were specifically designed to test visual processing. Therefore, the mechanisms behind behavioral responses likely also reflect the brain’s functional properties and not only the optical or neural properties of the eye itself.

CFF is indeed associated with cognitive performance, suggesting that its relationship 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 individuals 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.