Carotenoid substitution shows promise in secondary analysis of AREDS2 trial on progression of age-related macular degeneration

Recent results released on the effect of oral supplements on progression of age-related macular degeneration (AMD) have revealed some interesting issues relating to the effect of carotenoids. The original double-blind clinical trial, referred to as AREDS (age-related eye disease study), suggested risk of progression to advanced AMD was reduced by about 25 over 5 years compared to a ?placebo? (noting that the control group consisted of a population with existing moderate to severe AMD)1,2. The follow-on study, referred to as the AREDS2 trial, was completed recently with a modified formulation3,4. This study was widely reported and various commentaries and assessments have appeared in the literature5. Shortly afterwards, a supplementary paper describing additional secondary analyses added some further clarification on several issues6. One of the reasons for the modification was to address concerns that consumption of additional beta carotene in supplement form may lead to an increased incidence of lung cancer in smokers. Substitution of beta carotene using the carotenoids lutein and zeaxanthin was aimed at avoiding this problem. Lutein and zeaxanthin are major components of the macular pigment and protect the retina from UV radiation. Past clinical trials suggested that zeaxanthin may also improve visual acuity, but this was not confirmed in the current study due to design considerations7. The issues of stage of disease, dose and duration are also in need of further study in the future - which may lead to further insights.