A double-blind, placebo-controlled study on the effects of lutein and zeaxanthin on neural processing speed and efficiency

PLoS One. 2014 Sep 24;9(9):e108178. doi: 10.1371/journal.pone.0108178. eCollection 2014.


Lutein and zeaxanthin are major carotenoids in the eye but are also found in post-receptoral visual pathways. It has been hypothesized that these pigments influence the processing of visual signals within and post-retina, and that increasing lutein and zeaxanthin levels within the visual system will lead to increased visual processing speeds. To test this, we measured macular pigment density (as a biomarker of lutein and zeaxanthin levels in brain), critical flicker fusion (CFF) thresholds, and visual motor reaction time in young healthy subjects (n = 92). Changes in these outcome variables were also assessed after four months of supplementation with either placebo (n = 10), zeaxanthin only (20 mg/day; n = 29) or a mixed formulation containing 26 mg/day zeaxanthin, 8 mg/day lutein, and 190 mg/day mixed omega-3 fatty acids (n = 25). Significant correlations were found between retinal lutein and zeaxanthin (macular pigment) and CFF thresholds (p<0.01) and visual motor performance (overall p<0.01). Supplementation with zeaxanthin and the mixed formulation (considered together) produced significant (p<0.01) increases in CFF thresholds (∼12%) and visual motor reaction time (∼10%) compared to placebo. In general, increasing macular pigment density through supplementation (average increase of about 0.09 log units) resulted in significant improvements in visual processing speed, even when testing young, healthy individuals who tend to be at peak efficiency.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Dietary Supplements* / analysis
  • Double-Blind Method
  • Female
  • Flicker Fusion / drug effects*
  • Humans
  • Lutein / administration & dosage
  • Lutein / pharmacology*
  • Macular Pigment / metabolism*
  • Male
  • Retina / drug effects*
  • Retina / physiology
  • Vision Tests
  • Young Adult
  • Zeaxanthins / administration & dosage
  • Zeaxanthins / pharmacology*


  • Macular Pigment
  • Zeaxanthins
  • Lutein

Grant support

This study was funded by ZeaVision, LLC. http://www.zeavision.com/. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.