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

BMJ 2007; 335 doi: https://doi.org/10.1136/bmj.39350.500428.47 (Published 11 October 2007) Cite this as: BMJ 2007;335:755

Dietary antioxidants in AMD

Dear Sir,

I read with interest the review article published by Elaine W-T Chong
et al(1). I have one concern and one suggestion.

Their review shows that there is insufficient evidence to support the
role of dietary antioxidants, including the use of supplements for primary
prevention of early AMD (age related macular degeneration). But the
database mainly consisted of patients coming from relatively well
nourished patients from developed western countries. We already know that
in patients who have a well balanced diet rich in green leafy vegetables,
vitamin supplements may not be necessary. Thus this group of "well
nourished" patients do not need dietary anti-oxidants as they already
receive it in their proper diet.

But there is a whole group of patients in clinical practice who on
history taking and physical examination do not appear to have a balanced
diet(maybe because they come from a different socio-economic background)
and are also at a risk of AMD. This is where problems can arise. My
concern is if we take the conclusion drawn by the present study on face
value and stop advising patients on the basis of insufficient evidence
about need for a well balanced diet and in patients who do not have a well
balanced diet, the need for dietary anti-oxidants or supplements. There is
a potential that we may miss emphasising a preventive measure for AMD
which has the potential for devastating visual loss.

Also AREDS study(2) has shown a 28% reduction in the risk of
progression to advanced AMD compared to placebo by treatment with high
dose anti-oxidants supplement. We also know that genetic markers are a
risk factor(3). So it may be possible that anti-oxidants treatment may
have a role to play in prevention of AMD in the relatives of patients who
have suffered from AMD. My suggestion is that a randomised control trial
looking at diet patterns and dietary anti-oxidants and supplements in
close relatives of AMD patients may shed further light on this subject.

References:

1. Chong E W-T, Wong TY, Kreis AJ, Simpson JA, Guymer RH. Dietary
antioxidants and primary prevention of age related macular degeneration:
systematic review and meta-analysis
BMJ 2007; 335: 755

2. Haines JL, Hauser MA, Schmidt S, Scott WK, Olson LM, Gallins P, et
al. Complement factor H variant increases the risk of age-related macular
degeneration. Science 2005;308:419-21.

3. Age-Related Eye Disease Study Research Group. A randomized,
placebo-controlled, clinical trial of high-dose supplementation with
vitamins C and E, beta carotene, and zinc for age-related macular
degeneration and vision loss: AREDS report No 8. Arch Ophthalmol
2001;119:1417-36

Competing interests:
None declared

Competing interests: No competing interests

15 October 2007
Sachin M Salvi
Specialist Registrar
Department of Ophthalmology, Royal Hallamshire Hospital, Glossop road, Sheffield S10 2JF