There is no shortage of research supporting the importance of Lutein and Zeaxanthin in eye and overall health. However, the third carotenoid found in the retina, meso-Zeaxanthin, still has some questions surrounding its importance.
A recent meta-analysis study over the three retinal carotenoids argues that while much of the evidence published only includes the two dietary antioxidants (Lutein and Zeaxanthin), the eyes required all three for optimal foveal health.Stuart Richer, OD, PhD wrote an article reviewing this analysis, saying that some of the claims are not science-based. He also argues that the differences throughout the included studies make it difficult to develop a definite conclusion.
In his writing, Dr. Richer recognized three of the authors’ claims as supported:
- Nutraceuticals containing Lutein and Zeaxanthin focus on increasing macular pigment optical density
- There’s a positive dose-response correlation between carotenoid intake and an increase in MPOD.
- MPOD continually improves when supplementation continues for 12+ months.
Beyond these points, the meta-analysis states that supplementation with all three carotenoids “improved MPOD both in age-related macular degeneration (AMD) patients and healthy subjects,” though there is no evidence to support this statement. None of the meso-Zeaxanthin studies included in the analysis contained patients with AMD.
The meta-analysis also misrepresented two other studies. The original Garcia-Layana study proved an increase in MPOD with Lutein supplementation, but the analysis listed the results as a decrease. The bone study was reported with a significant rise in MPOD when supplementing with all three carotenoids, but the original study results indicated a considerably lower value.
Dr. Richer expressed his concerns about the impact using non–dietary carotenoids like meso-Zeaxanthin could have on non-ocular tissues like the brain. He ends the article with this conclusion:
“The totality of discrepancies outlined above may substantially impact the conclusions of this meta-analysis. Therefore, the statement “a greater increase in MPOD was observed in trials combined with meso-zeaxanthin in comparison with those without meso-zeaxanthin” deserves careful further evaluation.”
To read the original article, click here.
If you enjoyed this post, or if you would like to read more by Dr. Richer, check out the Carotenoid Roundtable.