01 Jun 2015 - Eye Nutrition Meeting in Barcelona - Beyond AREDS

Was the AREDS2 report the end of the story for nutritional supplements for AMD prevention? Not according to the recent Eye Nutrition Meeting in Barcelona. 

Treatment for age-related macular degeneration (AMD) is a topic that seems to attract controversy. On issues such as NHS costs and drug efficacy, arguments surrounding AMD treatment now extend well outside the medical profession and into the public arena.

The role of diet and dietary supplements in AMD is not short on controversy either and again this debate is increasingly being played out in public.

When the best nutrients for eye health are published on the pages of The Daily Mail it may be time for all eye care practitioners to join that debate.

For practitioners, controversy around AMD and nutrition arises not from the popular press but from the results of two large-scale, multi-site intervention studies – the Age-Related Eye Disease Study (AREDS) and AREDS2 – funded by the US National Eye Institute and launched more than 20 years ago.

Published in 2001, the original AREDS report looked at the effects of vitamins C and E, Vitamin A (beta-carotene), and zinc supplementation on progression of AMD in those with intermediate or late AMD.

• High levels of antioxidants and zinc were found to significantly reduce the risk of advanced AMD and associated vision loss in those already in the later stages of the disease.

The authors concluded that those older than 55 years with AMD and at risk of progression, and without contraindications such as smoking, should consider taking a supplement of antioxidants plus zinc such as that used in this study.

The much-anticipated AREDS2 report, published in 2013, investigated whether adding lutein + zeaxanthin (the main components of macular pigment), the omega-3 fatty acids DHA + EPA, or both, to the original AREDS formulation decreased the risk of progression to advanced AMD, as observational studies had suggested. AREDS2 also evaluated the effect of eliminating beta-carotene, lowering zinc dose or both.

• The surprising finding was that the addition of these ingredients did not further reduce risk of progression to advanced AMD. However, because of a potential increased incidence of lung cancer in former smokers, lutein + zeaxanthin could successfully replace beta-carotene without the associated toxicity.

Given the findings of these large-scale randomised controlled clinical trials, could that be the end of the story?

And what are the clinical implications for eye care practitioners and their patients, not just for AMD progression but also for prevention?

Divided opinion

Experts were divided on their interpretation of AREDS2.

Some argued that while this complex study did not provide support for the use of supplements for the primary prevention of AMD, it reinforced the evidence for a specific combination of antioxidant vitamins and minerals, based on the original AREDS formula but with reduced zinc and no beta-carotene, for those AMD patients at greatest risk of progressing.

Some expressed surprise that, in view of other research, omega-3 appeared to make little difference to the risk of progression to advanced AMD.

There was also criticism of AREDS2 for weaknesses in the protocol, including that the population sample constituted ‘the worried well’.

The authors themselves acknowledged that ‘the study results may not be generalisable, because the study population is a highly selected group of highly educated and well-nourished people.’

• On one issue raised by the AREDS research there was more agreement: the merits of a healthy diet and lifestyle to eye health as well as general wellbeing. But given the quantities of foods that would need to be consumed to achieve the recommended intakes of lutein and zeaxanthin, dietary measures were recognised as less practical than taking a supplement.

Perhaps not surprising, then, that a dozen or more such supplements with differing formulations are now available in the UK, from a variety of suppliers and supply routes. The number of products on the market continues to grow and many of them are labelled and promoted as ‘AREDS2 formula’.

Yet since AREDS2 was released, many more studies have been published into the role of diet and dietary supplements, not just in AMD prevention and treatment but for other ocular conditions such as dry eye. Evidence is emerging that the story may be more complex still.

Is it time to move beyond AREDS and adapt our recommendation habits based on recent research?

Or, as some have suggested, should supplement formulations and dietary advice be based only on these two studies?

And what can we learn from population-based studies into the prevalence of AMD with, for instance, the Mediterranean diet?