Lutein and Zeaxanthin Benefit Young and Old Alike
By Irfan Qureshi
AREDS2 highlighted the importance of lutein and zeaxanthin for AMD, but recent studies also show benefits for younger populations.
Xanthophylls are yellow pigments and one of the two major subgroups in the carotenoid family. Lutein and zeaxanthin are two carotenoids within the xanthophyll family. From a nutritional standpoint, lutein and zeaxanthin are most well-renowned for their eye health benefits because they are the only two carotenoids accumulating in the macula of the retina in humans. These carotenoids form what is referred to as the macular pigment, which serves to filter harmful blue light and provides antioxidant benefits to protect retinal tissue. Research studies suggest beneficial effects related to nutritional supplementation with lutein and zeaxanthin, including prevention of macular degeneration, a leading cause of vision loss expected to impact nearly 200 million people globally by the year 2020.2 In fact, this research was the basis for conducting the well-known AREDS2 (Age-Related Eye Disease Study 2) trial.
The original AREDS (Age-Related Eye Disease Study) found that daily supplementation with a combination of antioxidant vitamins and minerals reduced the risk of developing advanced age-related macular degeneration (AMD) by 25%. AREDS2 was conducted as a follow-up study between 2006 and 2012 and included 4,203 individuals aged 50 to 85 at risk for development of advanced AMD.3 The purpose of AREDS2 was to determine if supplementation with the nutrients lutein/zeaxanthin and omega-3 fatty acids yielded additional benefits for AMD prevention beyond the original AREDS formulation. Overall, the results of the study failed to show increased protection from AMD with the added lutein and zeaxanthin as well as omega-3 fatty acids beyond what was found in the original AREDS study. However, the researchers then looked at the data by dividing it into groups based on dietary intake of lutein and zeaxanthin. The groups with the lowest dietary intake of these nutrients showed significant increased protection against progression to advanced AMD from consuming the supplemental lutein and zeaxanthin. Thus it’s possible that those with the lowest dietary intakes of these carotenoids would benefit substantially by supplementing with these nutrients.
A further, and potentially significant, confounding factor pointed out by researchers includes the issue of competitive absorption of carotenoids. As the AREDS formula contains beta-carotene, the authors suggest that administering lutein and zeaxanthin concurrently with the original AREDS supplement (as was the case in AREDS2) could have diluted the protective effect of the latter carotenoids on the basis that significant quantities remained unabsorbed due to competitive absorption with beta-carotene.
Given this confounder, it’s not possible to conclusively say whether the addition of lutein and zeaxanthin to an AREDS-type multinutrient would yield significant additional protection against the progression of macular degeneration. For this, additional long-term studies excluding beta-carotene need to be conducted. However, more recent studies beyond AREDS2 continue to point to the substantial eye health benefits of supplementation with both lutein and zeaxanthin in individuals with macular degeneration as well as in those who are healthy.
Lutein and Zeaxanthin in AMD
Yang-Mu Huang and colleagues from Beijing conducted a randomized, double-blind, placebo-controlled study in 112 individuals aged 50 and older with early AMD to assess changes in retinal function with lutein and zeaxanthin supplementation.4 The researchers divided study subjects into four groups, including placebo, 10 mg lutein, 20 mg lutein, and 10 mg of lutein plus 10 mg of zeaxanthin daily. Supplementation commenced for a two-year period, and the researchers assessed measures of retinal sensitivity at baseline, at 48 weeks, and at two years.
Results of the study showed that all groups besides placebo achieved higher macular pigment optical density scores (MPOD). A higher density of macular pigment, composed primarily of lutein and zeaxanthin, is thought to confer better eye protection. Furthermore, retinal sensitivity was significantly enhanced in the groups receiving 10 and 20 mg of lutein daily versus placebo. While the authors clarified that the duration of the current study was too short to determine whether lutein supplementation reduces the progression of AMD, lutein supplementation was clearly shown to enhance parameters of retinal function.
Researchers in the field of carotenoid and eye disease research recently published a study in which they took a different approach to looking at the relationship of lutein and zeaxanthin in preventing AMD. Led by Kristen Meyers of the University of Wisconsin School of Medicine and Public Health,5 the group analyzed data from the CAREDS (Carotenoids in Age-Related Eye Disease Study) cohort, which was an ancillary study within the Women’s Health Initiative Observational Study, conducted between 2001 and 2004. The researchers developed a genetic model based on the presence of SNPs (single nucleotide polymorphisms, or variations in DNA occurring where a single nucleotide on a chromosome differs within populations) from 24 candidate genes dealing with carotenoid status, including those related to the binding, metabolism, or transport of macular carotenoids……
Read more: http://www.nutritionaloutlook.com/1504/Eye
Source: Nutritional Outlook