A Double-Blind, Placebo-Controlled Study on the Effects of Lutein and Zeaxanthin on Neural Processing Speed and Efficiency

Abstract

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.

A randomized placebo-controlled study on the effects of lutein and zeaxanthin on visual processing speed in young healthy subjects

“…Another possibility, more relevant to younger individuals and palliative approaches, is a direct improvement by some type of local interaction with neural cells (the so-called neural efficiency hypothesis; [11,36,21] MPOD) in young healthy subjects would yield behavioral improvements in tasks that are generally mediated by the central nervous system. 2 To test this idea, we measured MPOD and temporal vision (specifically, the temporal contrast sensitivity function, tCSF) in a group of young healthy subjects.…”

“…Significant relations have been reported between macular pigment optical density (MPOD; L and Z and meso-Z measured in the retina) and a large number of visual measures including glare disability and discomfort, photostress recovery, and chromatic contrast [13]. Measures of L and Z within the retina appear to be strongly linked to measures of L and Z in brain tissue [29] and MPOD has also been linked to measures that are mediated by brain such as cognition [15,9,23], auditory thresholds [33], balance time, reaction time [22], and temporal vision [11,21,2].Taken together, L and Z seem important to biology, in general, and humans are no exception. In many cases, the basis for their functional effects has been well characterized.…”

Leveraging Bioactives to Support Human Health through the Lifecycle: Scientific Evidence and Regulatory Considerations

“…Bovier et al found moderate but statistically signiicant improvements in both MPOD and cognitive function with lutein and zeaxanthin supplementation of young, healthy individuals considered to be at peak cognitive eiciency [34]. These studies suggest that both young, healthy adults and the elderly population can gain cognitive beneits from lutein and zeaxanthin supplementation.…”

Macular pigment in retinal health and disease

“…Additionally, MPOD correlates with processing speed and cognitive performance in healthy elderly subjects as well as those with mild cognitive impairment [47–49]. Another study found moderate but statistically significant improvements in both MPOD and visual processing speed when supplementing young and healthy individuals considered to be at peak cognitive efficiency [50]. …”