The LUNA (Lutein Nutrition effects measured by Autofluorescence) study, published in the journal Experimental Eye Research , appears to confirm the efficacy of lutein ester.
Lead researcher Dr. Meike Trieschmann from the Institute of Ophthalmology, St. Franziskus Hospital, Muenster in Germany looked at the effects of a daily supplement of 12 mg lutein for six months on macular pigment optical density of 108 adults with an average age of 72.
"A significant augmentation of macular pigment density was found in a majority of study subjects, including those afflicted with AMD.
The importance of these findings rests on the fact that the beneficial effects of these antioxidants can also be extended to subjects with established disease," said Trieschmann.
AMD affects the central part of the retina called the macula, which controls fine vision, leaving sufferers with only limited sight.
AMD affects over 30 million people worldwide, and is the leading cause of blindness in people over 50.
Previous studies have reported a link between AMD and lutein and zeaxanthin, found in leafy green vegetables, corn, egg yolks, squash, broccoli and peas.
The carotenoids proposedly reduce the risk of AMD by absorbing blue light that could damage the macula, preventing free radicals from damaging eye cells and strengthening eye cell membranes.
During the new study 108 adults took a daily antioxidant supplement (Ocuvite Lutein, provided by Bausch and Lomb who also funded the study) for six months.
The supplement contained 12 mg lutein ester, 1 mg zeaxanthin (Xangold, Cognis), 120 mg vitamin C, 17.6 mg vitamin E, 10 mg zinc, 40 mg selenium.
Nearly all subjects exhibited early symptoms of AMD.
A control group of 28 subjects received no food supplements.
The researchers report that blood levels of lutein increased four-fold in the intervention group (0.16 micrograms per millilitre at baseline to 0.593 micrograms/ml after 36 weeks).
A statistically significant average increase of 16 per cent in macular pigment density was also observed.
In addition, 25 per cent of the intervention group had increases in MPOD averaging 50 per cent, while no such increases were seen in the control group.
"Given the anatomic, biochemical and optical properties of MP (macular pigment), there is a biologically plausible rationale to suggest that supplemental lutein and/or zeaxanthin may delay, prevent, or modify the course of AMD," concluded the researchers.
The research was welcomed by Dr. Holger Becker, global product line manager for Xangold, who said: "It is a fact: Lutein from Xangold gets absorbed into the bloodstream and increases macular pigment density.
These significant findings provide valuable insights as Cognis works with customers worldwide to formulate products for rapidly aging populations facing declining eye health."
At this year's Vitafoods exhibition, Dr. Becker also presented work from an in vitro study by Hungarian and Ecuadorian researchers that reported that lutein esters pass unaltered through the stomach.
They arrive intact in the intestinal tract where they could be absorbed into the bloodstream.
"We know that the body digests and absorbs fat-soluble dietary compounds - like lutein esters - as part of the normal multi-stage digestive process," said Dr. Dr. Becker.
"New research by Peter Molnar suggests that this multi-stage process - which some have suggested can impair bioavailability of compounds in ester form - may in fact, do the opposite."
Source: Experimental Eye Research (Elsevier) April 2007, Volume 84, Issue 4, Pages 718-728 " Changes in macular pigment optical density (MPOD) and serum concentrations of its constituent carotenoids following supplemental lutein and zeaxanthin:
The LUNA study" Authors: M. Trieschmann, S. Beatty, J.M. Nolan, H.W. Hense, B. Heimes, U. Austermann, M. Fobker and D. Pauleikhoff Carotenoid Science 2006, Volume 10, Pages 1-5 "In vitro degradation of lutein but not lutein ester by gastric pH" Authors: P. Molnar, L.W. Levy, J. Deli