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The Macula Pigment Miracle

Friday, August 27, 2010


Evidence continues to mount that supports the role of dietary carotenoids, zeaxanthin, lutein and meso-zeaxanthin, in protecting against the development of age-related macular degeneration (AMD), the leading cause of vision loss in people over 55 years of age in the Western world.

A new study out of the Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, which was published in the August 2010 Archives of Biochemistry and Biophysics suggests that macular pigment direct quenching of singlet oxygen and scavenging free radicals is a major mechanism that helps prevent light-induced oxidative stress. The authors conclude that zeaxanthin, lutein and mezo-zeaxanthin act as intrinsic filters of short wavelength light to prevent or reduce the generation of singlet oxygen in the human retinal pigment epithelium (RPE) and choroid.  They also suggested that a mixture of these carotenoids quench more singlet oxygen than any one of these individual carotenoids at the same total concentration.

Again, the whole is more than the sum of its parts - particularly where micronutrients are concerned.

An equally important study published last year in the Journal of Lipid Research found that the xanthophyll carotenoids, zeaxanthin and lutein are preferentially taken up by the retinal cells compared to beta carotene. 
 
Researchers have also discovered the manner in which lutein and zeaxanthin are transported from the bloodstream to the eye, shedding further light on how these two macular pigment carotenoids promote eye health.

Because past studies have shown that a protein called SR-B1 is involved in intestinal absorption of lutein and zeaxanthin, the authors investigated whether the same protein is also involved in transporting these nutrients to the eye. The SR-B1 protein is scavenger receptor class B, type 1.

During the in vitro study, the researchers examined the uptake of lutein, zeaxanthin and beta carotene by human retinal pigment epithelial (RPE) cells. They found that the cells were more efficient at absorbing lutein and zeaxanthin compared to beta carotene and that when the protein SR-BI was active, the RPE cells absorbed the carotenoids. But when they added compounds to inhibit SR-BI, the uptake of zeaxanthin and beta-carotene were significantly decreased by between 40 and 60 percent. Inhibition of another transport protein, CD36, had no effect. This indicated that not only does SR-B1 help the intestines absorb lutein and zeaxanthin, it also helps the eyes absorb these two critical nutrients.
 
This study supports the potential of lutein and zeaxanthin to inhibit the development of age-related macular degeneration by providing a valid mechanism explaining how xanthophyll carotenoids can be transported from the blood into the eyes.
 
Another study published in Free Radical Biology Medicine suggests that lutein can decrease intracellular H(2)0(2) accumulation by scavenging superoxide and H(2)0(2) and the nuclear factor-kappaB (NF-kB) regulated inflammatory genes in lipopolysaccharide-stimulated macrophages. This suggests that lutein supplementation could be important for those at increased risk of both macular degeneration and Alzheimers, since these diseases share many of the same genes and both diseases are suggested to have an inflammatory component.
 
It is important to remember that the eye will convert lutein to meso-zeaxanin for the macula pigment if adequate amounts of lutein are available.  It is also important to remember that excess body fat interferes with lutein and zeaxanthin transport to the eye.
 
Ellen Troyer, MT MA
Biosyntrx CEO / Chief Research Officer

PEARL

Dennis Geirhart, PhD, the undisputed zeaxanthin guru and one of my most favorite researchers, will present a webinar for the Ocular Nutrition Society  on Wednesday September 1, 2010 between 5:00 -6:00 PM PDT on the macular pigment. This educational webinar is open to all eye care professionals. Space is limited so reserve your seat now at https://www2.gotomeeting.com/register/384630419

And don't forget to visit the Ocular Nutrition Society (ONS) web site www.ocularnutritionsociety.org to register for the November 16, 2010  pre-Academy of Optometry all day course in San Francisco called "From Testing to Tasting: An Integrative Approach to Eye Health."  This course promises to be entertaining education.
 


Crestpoint Management, LTD instrument announcement:
Barraquer Pediatric Speculum 9-570-2

References

Studies on the singlet oxygen scavenging mechanism of human macular pigment. Li B, Ahmen F, Bernstein P. Archives of Biochemistry and Biophysics August 2010 [abstract]

Xanthophylls are preferentially taken up compared with {beta}-carotene by retinal cells via a SRBI-dependent mechanism. During A, Doraiswamy S, Harrison EH. J Lipid Res. 2008 Aug;49(8):1715-24.[abstract]
 
The non-provitamin A carotenoid, lutein, inhibits NF-kappaB-dependent gene expression through redox-based regulation of the phosphatidylinositon 3-kinase/PTEN/Akt and NF-dappaB-incuding kinase pathways: Role of H(2)0(2) in NF-kappaB activation. Kim JH, Kim CK, et al. Free Radical Biology Medicine 2008 June 27 [abstract]