Addition of lutein, zeaxanthin and omega-3 fatty acids to nutritional supplements aimed at preventing eye disease has shown no benefit in preventing sight loss progression.
The Age-Related Eye Disease Study 2 (AREDS 2) reported the findings at last weekend's Association for Research in Vision and Ophthalmology conference in Seattle, USA.
AREDS 2 was designed to test whether adding lutein plus zeaxanthin, DHA plus EPA, or lutein plus zeaxanthin and DHA plus EPA to the AREDS formulation might further reduce the risk of progression to advanced AMD.
The study reported that there was no statistically significant overall effect on progression to advanced AMD or changes in visual acuity with the supplementation.
Researchers did, however, highlight that, because of potential increased incidence of lung cancer in former smokers, lutein plus zeaxanthin could be an appropriate carotenoid substitute in the AREDS formulation.
Around 4,000 participants across four treatment groups underwent follow-up for a median of 4.9 years.
The original AREDS study published in 2001 showed supplementation with a combination of antioxidant vitamins C and E with beta carotene and zinc reduced the risk of progression to advanced AMD in a sub-group of subjects already showing later stages of the disease. Supplementation for the relevant sub-group reduced the risk of developing advanced AMD by 25 per cent at five years.
At the time there was no usable preparation of lutein or zeaxanthin, the macular pigments found within the retina, for inclusion in the formula. An increased risk of lung cancer with beta carotene supplementation for smokers was also identified early on in the study.
Since the original study, a number of smaller scale studies and observations have suggested the benefits of supplementation with macular pigments and omega-3 long-chain polyunsaturated fatty acids DHA and EPA.
Helen Jackman, chief executive of the Macular Society, said: 'It is clear that AREDS 2 has not found a magic bullet for AMD. But this is a large and complex study and we have yet to have all the analysis of what it means.
'It appears to confirm the findings of the original AREDS study which suggested that the right formula of nutritional supplements can benefit some people with AMD. We may now be able to improve the formula and that is very welcome.'