Abstract
Purpose::
The role of antioxidants in the primary prevention of age-related macular degeneration (AMD) is unclear. We conducted a systematic review and meta-analysis of the evidence on dietary antioxidants, including dietary antioxidant supplements, in the primary prevention of AMD.
Methods::
Seven databases including Pubmed, Web of Science, Embase, Medline, Cochrane library and grey literature databases were systematically searched with no limits on the year or language of publication. References identified from pertinent articles were also retrieved. Articles in other languages were translated to English. Two reviewers independently searched the above databases and selected the studies using standardized criteria. Randomized clinical trials and prospective cohort studies were included. Of the retrieved papers, two reviewers independently performed study quality evaluation and data extraction; disagreements were resolved by discussion. Results were pooled quantitatively using meta-analytic methods.
Results::
Of the 4692 abstracts initially identified, 12 studies met the selection criteria (9 prospective cohort studies and 3 randomized clinical trials). The 9 prospective cohort studies provided data on a total sample size of 149,203 people, with 1878 early AMD cases. The antioxidants investigated differed across studies and not all studies contributed to the meta-analysis of each antioxidant. Pooled results from prospective cohort studies suggested that vitamin A, vitamin C, zinc, lutein, zeaxanthin, α-carotene, ß-carotene, ß-cryptoxanthin, lycopene have little or no effect in the primary prevention of early AMD (pooled odds ratio estimates range from 0.90 to 1.11). Vitamin E had a modest protective association for early AMD, with borderline significance (pooled odds ratio 0.83, 95% confidence intervals 0.68-1.02). The three randomized clinical trials did not show antioxidant supplements to be protective in the primary prevention of early AMD.
Conclusions::
There is insufficient evidence from the published literature to support the role of dietary antioxidants, including the use of dietary antioxidant supplements, for the primary prevention of early AMD.
Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • antioxidants