Abstract
We report on the short-term test-retest baseline variability in macular function tests in ZEASTRESS-Pilot participants (n = 18), on their cross-sectional correlation with macular pigment optical density (MPOD), and on the effects of four months (FUV4) of 20 mg/day zeaxanthin (ZX), followed by a four-month washout (FUV8; n = 24, age 50–81 years old). Outcomes included: MPOD at 0.5 and 2.0 deg eccentricity (MPOD-0.5 and -2.0); contrast sensitivity (CS); pattern-reversal electroretinogram (PERG) amplitude; dark-adapted 650 nm foveal cone sensitivity (DA650-FCS); and 500 mn parafoveal rod sensitivity (DA500-PFRS). All measures of macular function showed close test-retest correlation (Pearson’s r range: 0.744–0.946) and low coefficients of variation (CV range: 1.13%–4.00%). MPOD correlated in a complex fashion with macular function. Following supplementation, MPOD-0.5 and MPOD-2.0 increased at both FUV4 and FUV8 (p ≤ 0.0001 for all measures). Continued, delayed MPOD increase and a small, but significant (p = 0.012), CS increase was seen at FUV8 only in females. PERGs increased significantly at FUV4 (p = 0.0006), followed by a partial decline at FUV8. In conclusion, following ZX supplementation, MPOD increased significantly. There was no effect on DA-650 FCS or DA-500 PFRS. Both CS and PERG amplitudes increased following supplementation, but the effect varied between males and females. Additional studies appear warranted to confirm and characterize further these inter-gender differences.
Highlights
The xantophylls lutein (LT), zeaxanthin (ZX), and meso-zeaxanthin (MZ) are the main in vivo biochemical determinants of macular pigment (MP)
We showed that macular pigment optical density (MPOD) correlated better with cognitive function than serum levels of LT and ZX, suggesting that retinal in vivo levels of these carotenoids are a better proxy for actual neural uptake of LT and ZX than serum levels
To the best of our knowledge, the ZEASTRESS-Pilot is the first study to report on the effects of selective high-dose (20 mg/day) ZX supplementation in a group of participants of both genders on both MPOD and measures of macular function, which provided us with insight on the biology of ZX retinal uptake and its possible beneficial effects, while controlling for potential confounding from smoking, race, high body-mass index (BMI) at baseline, or BMI changes during the study
Summary
The xantophylls lutein (LT), zeaxanthin (ZX), and meso-zeaxanthin (MZ) are the main in vivo biochemical determinants of macular pigment (MP). Consistent, at least in part with these predictions, LT and ZX supplementation was effective in the AREDS2 trial in reducing the risk of progression to advanced disease in AMD [21], was shown to be preferable to the use of beta-carotene [22] In addition to these macula-specific benefits of xanthophyll supplementation, interest in these carotenoids has significantly increased in the past few years because of other neural correlates and effects. We showed that MPOD correlated better with cognitive function than serum levels of LT and ZX, suggesting that retinal in vivo levels of these carotenoids are a better proxy for actual neural uptake of LT and ZX than serum levels This finding was consistent with the notion that LT and ZX account for a large proportion of the carotenoids found in the frontal and occipital cortex [24]. There is much value in knowing which dietary supplements can be utilized to augment MPOD, what are its functional correlates, the extent of response to supplementation in vivo, and its dynamics
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
