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By: Stephen DANIELLS
Sustained supplementation with the macular carotenoids can lead to greater augmentation of macular pigment and improve contrast sensitivity, says a new study.
Different formulations of lutein, zeaxanthin and meso-zeaxanthin were examined in people with early age-related macular degeneration (AMD), with results showing that all of the combinations significantly improved macular pigment in the participants.
Furthermore, the formulation with 17 mg per day meso-zeaxanthin, 3 mg per day lutein, and 2 mg per day zeaxanthin was found to produce significant increases in macular pigmentation at each eccentricity, while no such increases were observed in the formulation with no meso-zeaxanthin (20 mg per day lutein and 0.86 mg per day zeaxanthin), according to results published in Eye.
“We report that the inclusion of meso-zeaxanthin in a supplement formulation seems to confer benefits in terms of macular pigment augmentation and in terms of enhanced contrast sensitivity in subjects with early AMD,”wrote the authors, led by Kwadwo Akuffo, a postgraduate research student at the Waterford Institute of Technology in Ireland.
“An important and novel finding rests on the observation that sustained supplementation with the macular carotenoids seems necessary to maximally augment macular pigment and to optimize contrast sensitivity over a 3-year period in patients with early AMD.”
Eyes
The macula is a yellow spot of about five millimeters diameter on the retina. As we age, levels of the pigments in the macula decrease naturally, thereby increasing the risk of age-related macular degeneration (AMD). The yellow color is due to the content of the carotenoids lutein and zeaxanthin, which we derive from the diet.
These compounds are the only carotenoids capable of filtering the harmful blue light than can damage the light receptor cells in the eye, the rods and the cones.
A too-thin macular pigment layer can allow the blue light through and destroy the cells. Maintaining high levels of the macular carotenoids, and therefore the macular pigment, is a valid approach to maintaining eye health and reducing the risk of AMD.
The majority of the science has focused on only lutein and zeaxanthin, but a 2013 study from the same research groups behind the new study reported that a combination of three carotenoids - lutein, zeaxanthin and meso-zeaxanthin – may be needed to boost retinal levels and support eye health (British Journal of Nutrition, Vol. 110, pp. 289-300).
The new study adds to this earlier data by finding that continuous supplementation for three years in people with early AMD did “further augment” the macular pigment, and improved the contrast sensitivity of the participants.
“The inclusion of meso-zeaxanthin in the formulation appears to be important if increases in macular pigment, and consequential improvements in vision, are to be maximized in subjects with early AMD receiving supplements,” wrote the researchers.
Supplements
The 67 people with early AMD enrolled in the trial took one of three supplementation regimes: The first group received supplements containing 20 mg per day lutein and 0.86 mg per day zeaxanthin, the second group received supplements containing 10 mg per day meso-zeaxanthin, 10 mg per day lutein, and 2 mg per day zeaxanthin, and the third group consumed supplements containing 17 mg per day meso-zeaxanthin, 3 mg per day lutein, and 2 mg per day zeaxanthin.
“Sustained supplementation appears necessary, for at least 3 years, if macular pigment is to be augmented maximally and contrast sensitivity is to be optimized over that period of time,” wrote the researchers. “Of note, modest visual benefits were observed in the current study.
“Future clinical trials should examine the impact of supplementation with formulations containing meso-zeaxanthin and zeaxanthin at similar doses. The Central Retinal Enrichment Supplementation Trial (CREST), currently underway, will also add to our understanding of the role of the macular carotenoids, including meso-zeaxanthin, on vision in healthy and diseased eyes.”
Meso-zeaxanthin is GRAS
Meso-zeaxanthin has been a divisive ingredient for the dietary supplement and functional food industries, with some suppliers taking the stance that the science behind meso-zeaxanthin is in its infancy and our knowledge is limited. On the other hand, Prof John Nolan and Prof Stephen Beatty from the Waterford Institute of Technology are convinced that all three macular pigments (lutein, zeaxanthin, and meso-zeaxanthin) are required for optimal eye health.
The FDA has issued two letters of no objection that meso-zeaxanthin is Generally Recognized As Safe (GRAS) for use in a variety of foods and beverages. Please click the following links for those letters:
Notifier: Industrial Organical S.A. de C.V. from Mexico (issued April 11, 2014)
Notifier: InnoBio Limited from China (issued March 27, 2015)
Affiliations
The new study was a collaboration between scientists from the Waterford Institute of Technology, the Howard Foundation (Cambridge, UK), the University of Wisconsin, Madison, and the University of Ulster (Northern Ireland).
Source: Eye
Volume 29, Pages 902–912; doi:10.1038/eye.2015.64
“Sustained supplementation and monitored response with differing carotenoid formulations in early age-related macular degeneration”
Authors:K.O. Akuffo, J.M. Nolan, A.N. Howard, et al.