Dietary antioxidants and primary prevention of age related macular degeneration: systematic review and meta-analysis

Abstract

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. INTRODUCTIONAge related macular degeneration (AMD) is the leading cause of severe visual loss in people aged over 50 in the developed world.1-7 Early AMD is characterised clinically by yellow deposits known as drusen and changes in pigmentation of the retina. Late AMD develops when there is an ingrowth of new blood vessels that bleed into the subretinal space (exudative or "wet" type) or when the macula atrophies (geographic atrophy or "dry" type). Both these conditions usually

Review of nutrient actions on age-related macular degeneration

“…A meta-analysis published by Chong et al of randomized controlled trials reported an odds ratio of 0.75, which was obtained by pooling the results from two studies: the Rotterdam eye study [46] and the Beaver Dam eye study [40,47]. The results from subsequent meta-analyses performed by Chong et al [40] and by Evans and Lawrenson [35] did not support a specific role for vitamin E in the prevention of AMD. To explain the discordant data of dietary vitamin E compared with the supplements, Evans and Lawrenson concluded that dietary vitamin E might be a marker for other nutrients with a role in the susceptibility of AMD [35].…”

“…Data from the National Health and Nutrition Examination Survey, reported by Goldberg et al, showed a negative association between the frequency of fruit and vegetables rich in vitamin A consumed and the prevalence of AMD [16]. However, several subsequent studies and a large metaanalysis failed to confirm this association [20,22,39,40], and unexpectedly, one report even suggested an increased risk in the development of late AMD in participants who took vitamin A [41]. With these conflicting results, more research is needed regarding the association between vitamin A and AMD.…”

“…22 demonstrated an association between the high intake of β-carotene and vitamins C and E, as well as a reduced likelihood of neovascular AMD [20]. A meta-analysis published by Chong et al of randomized controlled trials reported an odds ratio of 0.75, which was obtained by pooling the results from two studies: the Rotterdam eye study [46] and the Beaver Dam eye study [40,47]. The results from subsequent meta-analyses performed by Chong et al [40] and by Evans and Lawrenson [35] did not support a specific role for vitamin E in the prevention of AMD.…”

“…Nevertheless, SanGiovanni et al reported a reduced likelihood of neovascular AMD in subjects reporting high intakes of β-carotene and vitamins C and E [20]. In the meta-analysis performed by Chong et al, the pooled odds ratio of vitamin C supplements was 1.11 (95% CI, 0.84-1.46), in reference to early AMD [40]. Further research is needed to draw any definite conclusions regarding vitamin C and AMD.…”

Aging of perennial cells and organ parts according to the programmed aging paradigm

“…Moreover, while "The retina, with its high oxygen content and constant exposure to light, is particularly susceptible to oxidative damage" (Chong et al 2007), the meta-analysis of 12 studies did not show that antioxidant supplements prevented early AMD (Chong et al 2007). …”