A double-blind, placebo-controlled study on the effects of lutein and zeaxanthin on neural processing speed and efficiency.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 25251377 · doi:10.1371/journal.pone.0108178
What was done
In 92 young, healthy subjects, researchers measured macular pigment density (as a biomarker of central nervous system lutein and zeaxanthin), critical flicker fusion (CFF) thresholds, and visual motor reaction time. A subset completed a 4-month double-blind trial receiving daily placebo (n=10), 20 mg/day zeaxanthin (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) to assess changes in visual processing parameters.
What was found
Retinal macular pigment density correlated significantly with CFF thresholds (p<0.01) and visual motor performance (overall p<0.01). Supplementation across both active formulation groups combined led to an average macular pigment density increase of about 0.09 log units, a ~12% increase in CFF thresholds (p<0.01), and a ~10% improvement in visual motor reaction time (p<0.01) relative to placebo.
Why it matters
This study suggests that enhancing macular carotenoid levels can measurably improve neural processing speed and visual motor efficiency even in healthy young adults already at peak cognitive and sensory capacity.
Limits
The intervention trial had a small total sample size (n=64) with an unbalanced, very small placebo group (n=10). Treatment effects were reported for pooled active groups rather than isolating the distinct formulations against placebo, and the mixed arm contained omega-3 fatty acids, introducing a potential confounding nutrient.
Cited by
- supports A University of Georgia study found that supplementation with the carotenoids lutein and zeaxanthin resulted in a 20% increase in visual processing speed in young, healthy college students.