A randomized placebo-controlled study on the effects of lutein and zeaxanthin on visual processing speed in young healthy subjects.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 25483230 · doi:10.1016/j.abb.2014.11.012
What was done
Researchers initially tested the cross-sectional correlation between macular pigment optical density (MPOD) and visual processing speed, measured psychophysically via the temporal contrast sensitivity function (tCSF), in 102 young healthy subjects. In a follow-up trial, 69 subjects were randomized to receive either a placebo (n=15) or one of two lutein and zeaxanthin supplements (n=54 total). MPOD and tCSF were measured at baseline and after 4 months of supplementation.
What was found
MPOD correlated positively with tCSF at baseline in the cohort of 102 participants. In the randomized trial of 69 participants, the placebo group showed no changes in MPOD or tCSF at 4 months, whereas both metrics improved significantly in subjects receiving lutein and zeaxanthin supplements. Specific numerical values, effect sizes, and p-values were not reported in the abstract.
Why it matters
This indicates that dietary supplementation with macular carotenoids may improve visual processing speed even in young, healthy individuals without preexisting visual deficits.
Limits
The abstract reports no numerical data, confidence intervals, or p-values for the baseline correlation or treatment effects. The sample size is modest, with an unbalanced allocation (15 placebo vs. 54 active across two groups), and the trial duration was limited to 4 months in a healthy young demographic.
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.