- Elaine W-T Chong, PhD candidate1,
- Tien Y Wong, professor of ophthalmology1,
- Andreas J Kreis, ophthalmology fellow1,
- Julie A Simpson, senior lecturer2,
- Robyn H Guymer, associate professor of ophthalmology1
- 1Centre for Eye Research Australia, University of Melbourne, Victoria 3002, Australia
- 2Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne
- Correspondence to: T Y Wong,
- Accepted 30 July 2007
Objective To evaluate the effectiveness of dietary antioxidants in the primary prevention of age related macular degeneration (AMD).
Design Systematic review and meta-analysis.
Data sources Search of seven databases without limits on year or language of publication, and retrieval of references in pertinent reviews and articles.
Methods Two reviewers independently searched the databases and selected the studies, using standardised criteria. Randomised clinical trials and prospective cohort studies were included. Of the 4192 abstracts initially identified, 12 studies (nine prospective cohort studies and three randomised clinical trials) met the selection criteria and were included. Data extraction and study quality evaluation were independently reviewed, using standardised criteria. Results were pooled quantitatively using meta-analytic methods.
Results The nine prospective cohort studies included 149 203 people, with 1878 incident cases of early AMD. The antioxidants investigated differed across studies, and not all studies contributed to the meta-analysis of each antioxidant. Pooled results from prospective cohort studies indicated that vitamin A, vitamin C, vitamin E, zinc, lutein, zeaxanthin, α carotene, β carotene, β cryptoxanthin, and lycopene have little or no effect in the primary prevention of early AMD. The three randomised clinical trials did not show that antioxidant supplements prevented early AMD.
Conclusions There is insufficient evidence to support the role of dietary antioxidants, including the use of dietary antioxidant supplements, for the primary prevention of early AMD.
We thank Rachel L McIntosh of the Centre for Eye Research Australia, the University of Melbourne, for her help in starting this systematic review and Liubov Robman, also of the centre, for comments and advice.
Contributors: All authors contributed to the concept, design and critical revision of the manuscript. EW-TC and AJK carried out the search, selected the articles and extracted the data. EW-TC carried out the statistical analyses with input from JAS. TYW had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Funding: EW-TC received a National Health and Medical Research Council public health scholarship, funded by the Federal Government of Australia. TYW and RHG are on advisory boards of Pfizer and Novartis and have received grants, honoraria, and travelling fees from these companies.
Competing interests: None declared.
Ethical approval: Not required.
Provenance and peer review: Not commissioned; externally peer reviewed.
- Accepted 30 July 2007