The findings suggest that a much larger group of at-risk individuals than previously thought may gain some benefit from taking lutein supplements.
Age-related macular degeneration is the leading cause of blindness in the western world, affecting an estimated 30 million people worldwide. This number is expected to double by 2030. But Ian Murray, lead researcher on the new trial published in the July issue of Experimental Eye Research (79, pp21-27), says that about 20 per cent of individuals over the age of 65 have the early signs (changes in retinal cell pigmentation) of the disease, even though many may not know about it.
Dr Murray and colleagues from the Department of Optometry and Neuroscience at the University of Manchester in the UK evaluated the effects of a lutein esters supplement over a period of 18-20 weeks, in seven patients with early stages of the disease (age-related maculopathy) and six age-matched controls.
The subjects were given a daily dose of 20 mg of Xangold brand natural lutein esters, made by Cognis, and 'equivalent to the consumption of 10 mg free lutein', according to the researchers.
Macular pigment density and levels of lutein in blood plasma were measured at regular intervals throughout the study. Both increased significantly, and to the same extent in the controls and in the ARM patients, providing evidence that the macula can accumulate lutein, not only in healthy eyes but in those with the early stages of AMD.
"We observed a statistically significant rise in macular pigment optical density in eyes with ARM, and the degree of macular pigment augmentation was statistically similar to the healthy eyes. The importance of this finding, if replicated in further studies, rests on the fact that any putative beneficial effect of MP will not be restricted to subjects without evidence of the established disease," write the researchers.
The findings that diseased eyes can also take up extra lutein have also been demonstrated in a recent study by US researchers who found that AMD patients who took lutein supplements could reverse some of the symptoms of the disease. They experienced improvements in glare recovery, contrast sensitivity and visual acuity, compared with patients taking the placebo. Patients also experienced a 50 per cent increase in macular pigment density relative to those on placebo.
Dr Murray said he was "excited by the prospect that a simple addition to the diet may impede the progress of the disease and prevent others who are at risk experiencing such problems. Right now, dietary intervention is the only hope for most of them".
He added that a larger trial was "essential" to find out why some of those taking the supplements did not show any increase in macular pigment.