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ORIGINAL CONTRIBUTION
Dietary Intake of Antioxidants and Risk
of Age-Related Macular Degeneration
Redmer van Leeuwen, MD, PhD
Sharmila Boekhoorn, MD
Johannes R. Vingerling, MD, PhD
Jacqueline C. M. Witteman, PhD
Caroline C. W. Klaver, MD, PhD
Albert Hofman, MD, PhD
Paulus T. V. M. de Jong, MD, PhD
AGE-RELATED MACULAR DEGEN-
eration (AMD) is a degenera-
tive disorder of the macula,
the central part of the retina.
Late-stage AMD results in an inability
to read, recognize faces, drive, or move
freely. Early AMD is the subclinical
stage of the disease and can be diag-
nosed by funduscopy. The prevalence
of late AMD steeply increases with age,
affecting 11.5% of white persons older
than 80 years.1In the absence of effec-
tive treatment for AMD, the number of
patients severely disabled by late-
stage AMD is expected to increase in
the next 20 years by more than 50% to
3 million in the United States alone.1
The pathophysiology of AMD is still
poorly understood, and AMD may in fact
be a constellation of diseases with dif-
ferent causes. As in other age-related dis-
orders, oxidative stress has been impli-
cated in the etiology of AMD.2The retina
seems particularly susceptible to oxida-
tive stress because of its high concen-
tration of oxygen, polyunsaturated fatty
acids, and photosensitizers, in combi-
nation with an intense exposure to light.3
Epidemiological studies evaluating both
dietary intake and serum levels of anti-
oxidant vitamins and AMD have pro-
vided conflicting results.4-7 In the ran-
domized, placebo-controlled Age-
Related Eye Disease Study (AREDS),
supplements containing 5 to 13 times the
recommended daily allowance (RDA) of
beta carotene, vitamins C and E, and zinc
given to participants from retinal clin-
ics with early or monocular late AMD
resulted in a 25% reduction in the 5-year
progression to late AMD.8We sought to
investigate whether antioxidants, as
present in normal daily foods, may play
a role in the primary prevention of AMD.
METHODS
Study Population
The Rotterdam Study is a population-
based, prospective cohort study of the
frequency and determinants of com-
mon cardiovascular, locomotor, neu-
rologic, and ophthalmologic dis-
eases.9,10 The eligible population
comprised all 10 275 inhabitants aged
Author Affiliations: Departments of Epidemiology and
Biostatistics (Drs van Leeuwen, Boekhoorn, Vinger-
ling, Witteman, Klaver, Hofman, and de Jong) and
Ophthalmology (Drs van Leeuwen, Vingerling, and
Klaver), Erasmus Medical Centre, Rotterdam, the Neth-
erlands; Netherlands Ophthalmic Research Institute,
Royal Netherlands Academy of Arts and Sciences
(KNAW) (Drs Klaver and de Jong), and Department
of Ophthalmology, Academic Medical Centre (Dr de
Jong), Amsterdam, the Netherlands.
Corresponding Author: Paulus T. V. M. de Jong, MD,
PhD, Netherlands Ophthalmic Research Institute,
KNAW, Meibergdreef 47, 1105 BA Amsterdam, the
Netherlands (p.dejong@ioi.knaw.nl).
Context Age-related macular degeneration (AMD) is the most prevalent cause of
irreversible blindness in developed countries. Recently, high-dose supplementation with
beta carotene, vitamins C and E, and zinc was shown to slow the progression of AMD.
Objective To investigate whether regular dietary intake of antioxidants is associ-
ated with a lower risk of incident AMD.
Design Dietary intake was assessed at baseline in the Rotterdam Study (1990-
1993) using a semiquantitative food frequency questionnaire. Incident AMD until fi-
nal follow-up in 2004 was determined by grading fundus color transparencies in a masked
way according to the International Classification and Grading System.
Setting Population-based cohort of all inhabitants aged 55 years or older in a middle-
class suburb of Rotterdam, the Netherlands.
Participants Of 5836 persons at risk of AMD at baseline, 4765 had reliable dietary
data and 4170 participated in the follow-up.
Main Outcome Measure Incident AMD, defined as soft distinct drusen with pig-
ment alterations, indistinct or reticular drusen, geographic atrophy, or choroidal neo-
vascularization.
Results Incident AMD occurred in 560 participants after a mean follow-up of 8.0
years (range, 0.3-13.9 years). Dietary intake of both vitamin E and zinc was inversely
associated with incident AMD. The hazard ratio (HR) per standard deviation increase
of intake for vitamin E was 0.92 (95% confidence interval [CI], 0.84-1.00) and for
zinc was 0.91 (95% CI, 0.83-0.98). An above-median intake of all 4 nutrients, beta
carotene, vitamin C, vitamin E, and zinc, was associated with a 35% reduced risk (HR,
0.65; 95% CI, 0.46-0.92) of AMD. Exclusion of supplement users did not affect the
results.
Conclusion In this study, a high dietary intake of beta carotene, vitamins C and E,
and zinc was associated with a substantially reduced risk of AMD in elderly persons.
JAMA. 2005;294:3101-3107 www.jama.com
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55 years or older of a middle-class sub-
urb of Rotterdam, the Netherlands, of
whom 7983 (78%) participated. Be-
cause the ophthalmologic part of the
study became operational after the pi-
lot phase of the study had started, 6780
(66%) took part in the ophthalmic ex-
aminations. A baseline home inter-
view and examinations at the study cen-
ter were performed from 1990 to mid
1993, followed by a first follow-up ex-
amination from 1993 to 1994, a sec-
ond from mid 1997 to the end of 1999,
and a third examination from 2000 to
the end of 2004. Written informed con-
sent was obtained from all partici-
pants. The medical ethics committee of
Erasmus University approved the study
protocol.
Diagnosis of AMD
The eye examination included 35° fun-
dus photography (Topcon TRV-50VT
fundus camera, Topcon Optical Co,
Tokyo, Japan) after pharmacologic my-
driasis.10 Transparencies were graded
with 12.5⫻magnification according to
the International Classification and
Grading System.11 Two experienced
graders, masked to dietary intake,
graded the follow-up transparencies and
afterward compared these with the
baseline ones. The grading proce-
dures, definitions, and graders were
identical at baseline and follow-up.
Consensus sessions and between-
grader comparisons were performed
regularly. Weighted values were
0.72 for soft distinct drusen, 0.80 for
hyperpigmentation, and 0.58 for
hypopigmentation.
Early-stage AMD was defined as the
presence of either large (ⱖ63 µm), soft,
distinct drusen with pigment irregu-
larities or indistinct (ⱖ125 µm) or re-
ticular drusen with or without pig-
ment irregularities. Drusen are white
deposits in the retina that are consid-
ered to be the hallmark of early AMD
and are important predictors of late
AMD.10,12 Late-stage AMD, mostly lead-
ing to blindness, was defined as geo-
graphic atrophy (both central and non-
central), choroidal neovascularization,
or a combination of both.11
Dietary Assessment
At baseline, participants completed a
checklist at home that queried foods
and drinks they had consumed at least
twice a month during the preceding
year as well as dietary habits, use of
supplements, and prescribed diets.
Next, during their visit to the research
center, they underwent a standard-
ized interview with a dietitian based on
the checklist, using a 170-item semi-
quantitative food frequency question-
naire.13,14 A validation study compar-
ing this questionnaire with a 2-week
food diary demonstrated reproducible
and valid estimates.13,14 These dietary
data were converted to total energy in-
take and nutrient intake per day with
the computerized Dutch Food Com-
position Table.15 For the current study,
we selected the carotenoids alpha and
beta carotene, beta cryptoxanthin, lu-
tein/zeaxanthin, lycopene, vitamins A
(retinol equivalents), C, and E, and iron
and zinc as cofactors for antioxidant en-
zymes. Persons who reported taking
supplements containing carotenoids, vi-
tamins A, C, or E, iron, or zinc, as well
as multivitamins or multiminerals, were
classified as supplement users.
Assessment of Confounders
Information on potential confounders
was collected at baseline. Smoking sta-
tus was categorized as current, former,
or never, and number of pack-years was
calculated. Serum total cholesterol level
was measured in nonfasting blood
samples with an automated enzymatic
procedure. Blood pressure was defined
as the mean of 2 measurements in sit-
ting position at the right brachial ar-
tery with a random zero sphygmoma-
nometer. The ankle-arm index was
calculated by taking the ratio of sys-
tolic blood pressure at the ankle to sys-
tolic blood pressure at the arm, using the
lowest ratio of both legs. Carotid intima-
media thickness and atherosclerotic
plaques were assessed ultrasonographi-
cally and aortic calcifications on lateral
radiographic films of the lumbar spine.
A subclinical atherosclerosis compos-
ite score (range, 1-4) was constructed by
summing points for the population-
based deciles of carotid wall thickness
and ankle-arm index, with points added
for the presence of carotid plaques and
aortic calcifications.16
Study Sample
The cohort at risk consisted of 5836
persons with no AMD in either eye at
baseline; ie, with no drusen or pig-
ment irregularities, hard drusen only,
or soft drusen without pigment irregu-
larities. Incidence of AMD was de-
fined as the presence of early- or late-
stage AMD in at least 1 eye at 1 of the
follow-up examinations. Persons with
incident AMD were compared with
those with no AMD at baseline and no
AMD at any follow-up examinations.
Dietary intake was not assessed in
227 participants with decreased cog-
nitive function (defined as a score
⬍80 on the Cambridge Examination
of Mental Disorders in the Elderly)17
because their dietary history was
deemed unreliable. We also excluded
179 nursing home residents because
their food was prepared by nursing
home staff and would not reflect past
dietary habits. Reliable dietary data
were missing in 665 participants
because of logical inconsistencies in
dietary interviews, missing the base-
line dietitian visit when the food-
frequency questionnaire was admin-
istered, or various other logistical
reasons. Baseline characteristics were
similar in the 2 groups, although eli-
gible respondents without dietary data
were, on average, somewhat older
compared with those with data and
included fewer women.
Of this baseline cohort, 156 partici-
pants died, 419 refused any follow-up
examination, and 20 were lost to fol-
low-up before the first follow-up ex-
amination. Nonparticipants tended to
be older; included more women, nurs-
ing home residents, and smokers; and
more often had systemic hyperten-
sion. They did not differ from partici-
pants in their dietary intake of antioxi-
dants; eg, vitamin E (P=.75) or zinc
(P=.69). The study sample thus con-
sisted of 4170 participants who had nor-
mal cognition, lived independently, had
ANTIOXIDANTS AND AGE-RELATED MACULAR DEGENERATION
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reliable dietary assessment and grad-
able fundus transparencies, and par-
ticipated in at least 1 follow-up exami-
nation.
Data Analysis
We adjusted the dietary intake of an-
tioxidant nutrients for the total en-
ergy intake by means of the residual
method described by Willett.18 For each
nutrient, linear regression analysis was
performed with antioxidant intake as
the dependent variable and total en-
ergy intake as the independent vari-
able. This regression equation was used
to calculate the expected mean anti-
oxidant intake of the study popula-
tion for the mean total energy intake of
the study population. Next, for each in-
dividual, the energy-adjusted intake was
calculated by adding the expected mean
antioxidant intake of the study popu-
lation to the residual derived from the
regression analysis.
We estimated the risk of AMD asso-
ciated with the dietary intake of anti-
oxidant nutrients at baseline with Cox
proportional hazards regression analy-
sis. Intake of each nutrient was entered
into the model either as a linear term
per standard deviation or as a dummy
variable representing 1 of the 3 high-
est quartiles. Quartiles were analyzed
both as a categorical variable and as a
continuous variable to test for trend.
Quartiles and SDs were based on the dis-
tribution within the study sample. We
adjusted for age, sex, body mass index,
smoking status, pack-years of smok-
ing, systolic blood pressure, serum total
cholesterol, composite atherosclerosis
score, and alcohol intake in all analy-
ses. We additionally adjusted for intake
of polyunsaturated fat in the analysis
of the fat-soluble vitamin E because of
a reported association between this fat
and AMD.19 Missing values of categori-
cal variables were represented in the
model by a missing indicator. For con-
tinuous variables, missing values were
replaced by the mean or median of the
study sample, depending on the distri-
bution. Only the atherosclerosis com-
posite score had more than 1% of the
data missing (12.7%). To distinguish
between the effect of antioxidants from
food and from supplements, all analy-
ses were repeated after exclusion of
supplement users at baseline and also
after adding supplement users to the
highest quartile of dietary intake. Also,
analyses were repeated after stratifica-
tion for smoking status.
One of our aims was to study the
regular dietary intake of the combina-
tion of nutrients that had been admin-
istered at a high dose in AREDS.8To se-
cure large-enough groups with a
relatively high or low intake of each of
the 4 nutrients, we used the median in-
take per nutrient, based on the total
sample, as the cutoff value. The high-
intake group consisted of persons with
an above-median intake of each of the
4 nutrients. The low-intake group had
a below-median intake of each nutri-
ent, and all persons in between were
considered the reference category.
Associations are presented as haz-
ard ratios (HRs) with 95% confidence
intervals (CIs). All analyses were per-
formed using SPSS, release 11.0.1 (SPSS
Inc, Chicago, Ill).
RESULTS
Mean follow-up of participants was 8.0
years, with a range of 0.3 to 13.9 years
(median, 10.6 years). During this pe-
riod, 560 persons (13.4%) were diag-
nosed as having incident AMD, the ma-
jority of whom had early-stage AMD.
Persons with incident early AMD had
either large, soft drusen with pigment
irregularities (n= 317) or indistinct dru-
sen without (n= 124) or with (n = 77)
pigment irregularities. Of the 42 per-
sons with incident late-stage AMD, 14
had the atrophic and 28 the neovascu-
lar type. Twelve of them had AMD at
the second follow-up examination while
30 did so at the third follow-up. The in-
cidence of AMD in the study sample
was similar to the incidence in those
with missing data on dietary intake who
were not included in the sample (P=.60,
adjusted for age and sex). Baseline char-
acteristics of persons with incident
AMD as well as the remainder of the co-
hort are presented in TABLE 1. The
mean age was 68.2 years for the inci-
dent cases compared with 66.4 years for
the remainder (P⬍.001). Persons with
Table 1. Baseline Characteristics of the Study Sample (N = 4170)*
Characteristics
Incident Age-Related
Macular Degeneration
(n = 560)
No Age-Related
Macular Degeneration
at Follow-up
(n = 3610)
P
Value†
Age, y 68.2 (7.1) 66.4 (7.2) ⬍.001
Women, No. (%) 321 (57.3) 2151 (59.6) .31
Body mass index‡ 26.3 (3.5) 26.35 (3.6) .66
Smoking status, No. (%)
Never 183 (32.8) 1207 (33.6)
Former 248 (44.4) 1561 (43.4) .86
Current 127 (22.8) 825 (23.0)
Pack-years of smoking 18.5 (23.8) 16.4 (21.8) .04
Blood pressure, mm Hg
Systolic 138.9 (20.3) 137.1 (21.5) .76
Diastolic 73.4 (10.7) 73.9 (11.0) .56
Total cholesterol, mmol/L 6.6 (1.2) 6.7 (1.2) .93
High-density lipoprotein
cholesterol, mmol/L
1.38 (0.36) 1.35 (0.36) .02
Atherosclerosis composite
score§
2.7 (1.1) 2.5 (1.1) .21
Alcohol intake, g/d 10.8 (15.3) 10.6 (15.3) .20
Antioxidant supplement
users, No. (%)
60 (10.7) 499 (13.8) .09
SI conversions: To convert total and high-density lipoprotein cholesterol to mg/dL, divide by 0.0259.
*Data are expressed as mean (SD) unless otherwise indicated.
†Adjusted for age and sex.
‡Body mass index was calculated as weight in kilograms divided by the square of height in meters.
§Information on the atherosclerosis composite score is presented in the “Methods” section of the text.
ANTIOXIDANTS AND AGE-RELATED MACULAR DEGENERATION
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incident AMD reported more pack-
years of cigarette smoking (P=.04) and
had a higher serum high-density lipo-
protein cholesterol level (P=.02). Other
baseline characteristics were not dif-
ferent in the 2 groups.
TABLE 2shows the mean daily di-
etary intake of the antioxidant nutri-
ents in the study sample, adjusted for
total energy intake. In TABLE 3, the risk
of AMD in relation to nutrient intake
is presented. A significant inverse as-
sociation was observed for intake of vi-
tamin E, iron, and zinc. After adjust-
ment, a 1-SD increase in intake was
associated with a reduced risk of AMD
of 8% (95% CI, 0%-16%) for vitamin
E and 9% (95% CI, 2%-17%) for zinc.
The risk of AMD by quartile of nu-
trient intake is presented in the FIGURE.
The tests for trend for both vitamin E
(P=.04) and zinc (P= .06) intake indi-
cated a dose-response relationship be-
tween vitamin E and zinc intake and re-
duced risk of AMD.
TABLE 4presents the impact of the
combined dietary intake of the 4 anti-
oxidants that were studied in AREDS.8
Intake of these nutrients in the present
study was considerably lower than the
high-dose supplements used in AREDS.
An above-median intake of beta caro-
tene, vitamins C and E, and zinc, com-
pared with a below-median intake of at
least 1 of these nutrients, was associ-
ated with a reduced risk of AMD (HR,
0.65; 95% CI, 0.46-0.92) adjusted for
all potential confounders. In persons
with a below-median intake of all 4 nu-
trients, the risk of AMD was increased
but not significantly so (HR, 1.20; 95%
CI, 0.92-1.56).
Exclusion of the 559 participants
who used antioxidant supplements at
baseline did not substantially alter the
risk estimates (TABLE 5). In addition,
adding supplement users to the high-
est quartile of dietary intake did not
change the results (HR, adjusted for the
same factors as in Table 5, 0.77; 95%
CI, 0.61-0.98). Stratification for smok-
ing status did not substantially change
point estimates but widened the con-
fidence intervals (Table 5).
COMMENT
We found that high dietary intake of vi-
tamin E and zinc was associated with
a lower risk of incident AMD. An above-
median intake of the combination of vi-
tamins C and E, beta carotene, and zinc
was associated with a 35% lower risk
of incident AMD.
The strengths of our study were the
prospective design, the population-
based cohort, the detailed and similar
grading of AMD at baseline and follow-
up, and the long follow-up. Potential
Table 2. Mean Dietary Intake of Nutrients by Quartile in the Total Study Sample (N = 4170)
Quartile of Dietary Intake, mg/d
1 2 3 4
Mean (SD) Range Mean (SD) Range Mean (SD) Range Mean (SD) Range
Carotenoids
Alpha carotene 0.5 (0.2) ⱕ0.7 0.9 (0.01) ⬎0.7-ⱕ1.0 1.2 (0.1) ⬎1.0-ⱕ1.4 2.0 (1.2) ⬎1.4
Beta carotene 2.1 (0.6) ⱕ2.7 3.2 (0.2) ⬎2.7-ⱕ3.6 4.0 (0.3) ⬎3.6-ⱕ4.6 6.2 (0.3) ⬎4.6
Beta cryptoxanthin 0.05 (0.04) ⱕ0.1 0.2 (0.04) ⬎0.1-ⱕ0.3 0.3 (0.04) ⬎0.3-ⱕ0.4 0.6 (0.2) ⬎0.4
Lutein/zeaxanthin 1.4 (0.3) ⱕ1.8 2.0 (0.1) ⬎1.8-ⱕ2.2 2.5 (0.2) ⬎2.2-ⱕ2.8 3.6 (1.3) ⬎2.8
Lycopene 0.1 (0.07) ⱕ0.3 0.5 (0.1) ⬎0.3-ⱕ0.7 0.8 (0.1) ⬎0.7-ⱕ1.1 1.8 (0.8) ⬎1.1
Vitamins
Vitamin A (retinol equivalents) 0.5 (0.1) ⱕ0.6 0.7 (0.03) ⬎0.6-ⱕ0.8 0.8 (0.04) ⬎0.8-ⱕ0.9 1.2 (0.5) ⬎0.9
Vitamin C 63.7 (15.5) ⱕ84.5 99.4 (8.2) ⬎84.5-ⱕ113.6 128.4 (9.2) ⬎113.6-ⱕ146.1 189.3 (46.6) ⬎146.1
Vitamin E 7.6 (1.9) ⱕ9.9 11.4 (0.8) ⬎9.9-ⱕ12.8 14.4 (1.0) ⬎12.8-ⱕ16.2 20.2 (4.1) ⬎16.2
Trace elements
Iron 9.5 (1.0) ⱕ10.7 11.3 (0.4) ⬎10.7-ⱕ11.9 12.6 (0.4) ⬎11.9-ⱕ13.3 14.8 (1.6) ⬎13.3
Zinc 7.3 (0.9) ⱕ8.3 9.0 (0.4) ⬎8.3-ⱕ9.6 10.2 (0.4) ⬎9.6-ⱕ10.9 12.3 (1.4) ⬎10.9
Table 3. Risk of Age-Related Macular Degeneration per Standard Deviation (SD) Increase
in Dietary Intake of Antioxidant Nutrients
Nutrients
Mean Dietary Intake
(SD), mg/d
Adjusted Hazard Ratio
per 1-SD Increase
(95% Confidence Interval)*
Carotenoids
Alpha carotene 1.12 (0.84) 0.99 (0.94-1.06)
Beta carotene 3.84 (2.23) 1.00 (0.94-1.06)
Beta cryptoxanthin 0.29 (0.22) 1.01 (0.92-1.10)
Lutein/zeaxanthin 2.37 (1.08) 1.01 (0.93-1.09)
Lycopene 0.80 (0.80) 1.01 (0.97-1.04)
Vitamins
Vitamin A (retinol equivalents) 0.82 (0.35) 0.95 (0.86-1.05)
Vitamin C 120.20 (52.49) 1.02 (0.94-1.10)
Vitamin E 13.42 (5.19) 0.92 (0.84-1.00)
Trace elements
Iron 12.04 (2.16) 0.95 (0.86-1.04)
Zinc 9.67 (2.01) 0.91 (0.83-0.98)
*Adjusted for age, sex, body-mass index, smoking status, pack-years of smoking, systolic blood pressure, athero-
sclerosis composite score, serum total cholesterol, and alcohol intake.
ANTIOXIDANTS AND AGE-RELATED MACULAR DEGENERATION
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on March 5, 2008 www.jama.comDownloaded from
weaknesses were, as in all observa-
tional studies, selection bias, informa-
tion bias, and confounding. Selective
nonresponse was unlikely because non-
participants did not differ from partici-
pants in the dietary intake of antioxi-
dants. Bias in the diagnosis of AMD was
minimized by the masked grading of
photographs by persons unaware of the
antioxidant nutrient status. Misclassifi-
cation potentially could result from the
use of only 1 food questionnaire at base-
line, but such misclassification would be
nondifferential and, therefore, more
likely to underestimate the true asso-
ciations. The questionnaire was not vali-
dated for all nutrients included in the
current analysis; eg, specific carot-
enoids and vitamin E. However, for other
nutrients, the validity of the question-
naire was shown to be moderate to good.
The adjusted Pearson correlation coef-
ficient for vitamin A (including retinol
and beta carotene) was 0.48; for vita-
min C, 0.64; for iron, 0.42; and for zinc,
0.51.13,14 For vegetables, the correla-
tion was 0.39, and for fruit, 0.60. Since
alpha and beta carotene and lutein intake
are well correlated with total vegetable
intake, we presumed equal validity. The
same held for the correlation between
beta cryptoxanthin and vitamin C. It is
possible that other factors can explain
the reported associations. Although
we adjusted for known confounders,
such as smoking and atherosclerosis,
unknown factors associated with a
healthy diet still may have played a role.
The median nutrient intake used as
a cutoff value was at or above the RDA,
so the majority of our population pre-
sumably consumed a healthy diet. A
larger risk reduction was observed for
dietary intake above the RDA for all 4
micronutrients than for individual mi-
cronutrients. To ensure that diet was
the only source of antioxidant intake,
we repeated the analysis excluding per-
sons using antioxidant supplements at
baseline (13.4%) and also investi-
gated the combined effect of antioxi-
dants from food and from supple-
ments. This resulted in similar risk
estimates. The independent associa-
tion between antioxidant supple-
ments and AMD could not be exam-
ined because of the relatively small
number of antioxidant supplement us-
ers in our population and the lack of
data on duration and dosage of use.
Recent data suggest that oxidative
protein modifications may play a criti-
cal role in the formation of drusen.20
This implies that antioxidants may have
their strongest effect at the initiation of
the disease. We studied a cohort that
was free of clinical signs of early-stage
AMD at baseline, and our incident cases
were primarily affected by early AMD.
Early-stage AMD, however, is a strong
predictor of late-stage AMD.10,12 Exclu-
sion of the 42 persons with incident late
AMD did not change the results. We
therefore conclude that dietary anti-
oxidants may delay the development of
early AMD and, possibly, of AMD in
general.
Different antioxidants may act syn-
ergistically3; therefore, we studied the
combined effect of nutrients and used
the combination previously investi-
Figure. Hazard Ratios for Incident Age-Related Macular Degeneration by Quartile
of Energy-Adjusted Dietary Intake of Antioxidant Carotenoids
.89
.06
.63
.47
.04
P Value for Trend
.93
.79
.53
.65
.09
Trace Elements
Iron
Zinc
Vitamins
Vitamin A
Vitamin C
Vitamin E
Carotenoids
Alpha Carotene
Beta Carotene
Beta Cryptoxanthin
Lutein/Zeaxanthin
Lycopene
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Quartile
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
Hazard Ratio
0.5 12
Error bars indicate 95% confidence intervals. Adjusted for age, sex, body mass index, smoking status, pack-
years of smoking, systolic blood pressure, atherosclerosis composite score, serum total cholesterol, and alcohol
intake. The lowest quartile was considered the reference group. For each nutrient, the Pvalue of the test for
trend is given.
ANTIOXIDANTS AND AGE-RELATED MACULAR DEGENERATION
©2005 American Medical Association. All rights reserved. (Reprinted) JAMA, December 28, 2005—Vol 294, No. 24 3105
on March 5, 2008 www.jama.comDownloaded from
gated in AREDS.8We observed a dose-
response relationship with a mean in-
take of beta carotene, vitamins C and
E, and zinc as reference. Persons with
an above-median intake of these nutri-
ents may be different in other aspects.
This residual confounding is inherent
to an observational study and can only
be dealt with in a randomized trial.
However, experimental studies with a
randomized change in food consump-
tion are difficult to perform.
Previous studies have shown vari-
able degrees of protection against AMD
by different antioxidants. Dietary in-
take of vitamin E was not associated
with AMD risk in 1 case-control study
in persons with neovascular late AMD4
but showed an inverse association with
large drusen in a population-based
study.7A high intake of lutein and zea-
xanthin was associated with a 40%
lower risk of late AMD in 1 study4but
history of intake of these 2 nutrients was
not associated in another study.7A ran-
domized controlled trial of vitamin E
supplementation did not show an effect
on the incidence of early AMD after 4
years of follow-up.21 An inverse asso-
ciation between zinc intake and both
prevalent and incident early AMD was
reported in 1 population-based cohort
study22 but could not be confirmed in
another similar study23,24 or in a pooled
study in which late AMD and visual
acuity data were obtained by self-
report.25 In contrast with the aforemen-
tioned studies, our results were based
on long-term follow-up of a large, popu-
lation-based cohort with thorough base-
line assessment of dietary intake.
Recently, a meta-analysis of 19 clini-
cal trials including AREDS showed that
high-dosage (ⱖ400 IU/d) vitamin E
supplementation may increase all-
cause mortality.26 This finding would
challenge recommendations for supple-
ment use.8It should be noted that most
trials were performed in patients with
chronic diseases, in contrast with the
general population in our study sample.
The mean amount of vitamin E con-
sumed in diet in the highest quartile of
our cohort (20.2 mg/d [30 IU/d]) was
still considerably lower than high-
dose supplementation, and the bio-
availability of dietary antioxidants may
be different from that in supplements.
Dietary replacement also may be less ex-
pensive than supplement use.
This study suggests that the risk of
AMD can be modified by diet; in par-
ticular, by dietary vitamin E and zinc.
A higher intake of vitamin E can be
achieved by consumption of whole
grains, vegetable oil, eggs, and nuts.
High concentrations of zinc can be
found in meat, poultry, fish, whole
grains, and dairy products. Carrots,
kale, and spinach are the main suppli-
ers of beta carotene, while vitamin C
is found in citrus fruits and juices, green
peppers, broccoli, and potatoes. Based
on this study, foods high in these nu-
trients appear to be more important
than nutritional supplements. Until
more definitive data are available, this
information may be useful to persons
with signs of early AMD or to those with
a strong family history of AMD.27 Al-
though in need of confirmation, our ob-
servational data suggest that a high in-
take of specific antioxidants from a
regular diet may delay the develop-
ment of AMD.
Table 4. Risk of Age-Related Macular Degeneration by Category of Combined Intake of 4
Predefined Antioxidant Nutrients (Vitamins C and E, Beta Carotene, and Zinc)
Category of Dietary Intake*
Low
(n = 466)
Middle
(n = 3270)
High
(n = 434)
Cases of age-related macular degeneration,
No. (%)
76 (16.3) 442 (13.5) 42 (9.7)
Hazard ratio (95% confidence interval)
Unadjusted 1.31 (1.03-1.67) 1.00 0.65 (0.48-0.89)
Age- and sex-adjusted 1.23 (0.97-1.58) 1.00 0.68 (0.49-0.93)
Fully adjusted† 1.20 (0.92-1.56) 1.00 0.65 (0.46-0.92)
*Categories were defined by using the median energy-adjusted daily intake per nutrient as a cutoff value and classi-
fying above-median intake of all nutrients as high intake and below-median intake of all nutrients as low intake. Cut-
off values were 114 mg for vitamin C, 13 mg for vitamin E, 3.6 mg for beta carotene, and 9.6 mg for zinc.
†Adjusted for age, sex, body mass index, smoking status, pack-years of smoking, systolic blood pressure, athero-
sclerosis composite score, serum total cholesterol, and alcohol intake.
Table 5. Risk of Age-Related Macular Degeneration by Category of Combined Intake of 4
Predefined Antioxidant Nutrients (Vitamins C and E, Beta Carotene, and Zinc), Excluding
Supplement Users and Stratified by Smoking Status
Category of Dietary Intake*
Low Middle High
Excluding supplement users n = 419 n = 2816 n = 376
Cases, No. (%) 67 (16.0) 396 (14.1) 37 (9.8)
HR (95% CI)† 1.11 (0.84-1.46) 1.00 0.62 (0.43-0.90)
Smoking status
Never n = 128 n = 1096 n = 160
Cases, No. (%) 17 (13.3) 144 (13.3) 16 (10.0)
HR (95% CI)‡ 0.85 (0.48-1.50) 1.00 0.74 (0.42-1.31)
Former n = 182 n = 1434 n = 193
Cases, No. (%) 31 (17.0) 199 (13.9) 18 (9.3)
HR (95% CI)‡ 1.26 (0.84-1.99) 1.00 0.58 (0.34-0.98)
Current n = 154 n = 727 n = 77
Cases, No. (%) 28 (18.2) 97 (13.3) 8 (10.4)
HR (95% CI)‡ 1.44 (0.93-2.22) 1.00 0.65 (0.30-1.40)
Abbreviations: CI indicates confidence interval; HR, hazard ratio.
*Categories were defined by using the median energy-adjusted daily intake per nutrient as a cutoff value and classi-
fying above-median intake of all nutrients as high intake and below-median intake of all nutrients as low intake. Cut-
off values were 114 mg for vitamin C, 13 mg for vitamin E, 3.6 mg for beta carotene, and 9.6 mg for zinc.
†Adjusted for age, sex, body mass index, smoking status, pack-years of smoking, systolic blood pressure, athero-
sclerosis composite score, serum total cholesterol, and alcohol intake.
‡Adjusted for all of the above except smoking status and pack-years of smoking.
ANTIOXIDANTS AND AGE-RELATED MACULAR DEGENERATION
3106 JAMA, December 28, 2005—Vol 294, No. 24 (Reprinted) ©2005 American Medical Association. All rights reserved.
on March 5, 2008 www.jama.comDownloaded from
Author Contributions: Dr de Jong 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.
Study concept and design: Klaver, Hofman, de Jong.
Acquisition of data: van Leeuwen, Boekhoorn,
Vingerling, Witteman, Klaver.
Analysis and interpretation of data: van Leeuwen,
Boekhoorn, Vingerling, Witteman, Klaver, Hofman,
de Jong.
Drafting of the manuscript: van Leeuwen, Klaver.
Critical revision of the manuscript for important in-
tellectual content: Boekhoorn, Vingerling, Witteman,
Klaver, Hofman, de Jong.
Statistical analysis: van Leeuwen, Boekhoorn, Klaver.
Obtained funding: Hofman, de Jong.
Study supervision: Vingerling, Witteman, Klaver,
Hofman, de Jong.
Financial Disclosures: None reported.
Funding/Support: This study was supported by unre-
stricted grants from the following organizations: Neth-
erlands Organization for Scientific Research, the Hague;
Optimix, Amsterdam; Physico Therapeutic Institute, Rot-
terdam; Blindenpenning, Amsterdam; Sint Laurens In-
stitute, Rotterdam; Bevordering van Volkskracht, Rot-
terdam; Blindenhulp, the Hague; Rotterdamse
Blindenbelangen Association, Rotterdam; Oogheelkun-
dige Ondersteuning, the Hague; kfHein, Utrecht; Oo-
glijders, Rotterdam; Prins Bernhard Cultuurfonds, Am-
sterdam; Van Leeuwen Van Lignac, Rotterdam;
Verhagen, Rotterdam; General Netherlands Society for
the Prevention of Blindness, Doorn; Landelijke Sticht-
ing voor Blinden en Slechtzienden, Utrecht; and Elise
Mathilde, Maarn. An unrestricted grant was obtained
from Topcon Europe BV, Capelle aan de IJssel.
Role of the Sponsors: The study’s sponsors had no role
in the design and conduct of the study; in the collec-
tion, analysis, and interpretation of the data; or in the
preparation, review, and approval of the manuscript.
Acknowledgment: We thank Astrid E. Fletcher, PhD,
London School of Hygiene and Tropical Medicine,
University of London, and Edwin M. Stone, MD, PhD,
Department of Ophthalmology and Visual Sciences,
University of Iowa, for their critical and valuable com-
ments.
REFERENCES
1. Eye Disease Prevalence Research Group. Preva-
lence of age-related macular degeneration in the United
States. Arch Ophthalmol. 2004;122:564-572.
2. Zarbin MA. Current concepts in the pathogenesis
of age-related macular degeneration. Arch
Ophthalmol. 2004;122:598-614.
3. Beatty S, Koh H, Phil M, Henson D, Boulton M.
The role of oxidative stress in the pathogenesis of age-
related macular degeneration. Surv Ophthalmol. 2000;
45:115-134.
4. Seddon JM, Ajani UA, Sperduto RD, et al; Eye Dis-
ease Case-Control Study Group. Dietary carot-
enoids, vitamins A, C, and E, and advanced age-
related macular degeneration. JAMA. 1994;272:1413-
1420.
5. Snellen EL, Verbeek AL, Van Den Hoogen GW,
Cruysberg JR, Hoyng CB. Neovascular age-related
macular degeneration and its relationship to antioxi-
dant intake. Acta Ophthalmol Scand. 2002;80:
368-371.
6. Goldberg J, Flowerdew G, Smith E, Brody JA, Tso
MO. Factors associated with age-related macular de-
generation: an analysis of data from the first Na-
tional Health and Nutrition Examination Survey.
Am J Epidemiol. 1988;128:700-710.
7. VandenLangenberg GM, Mares-Perlman JA, Klein
R, Klein BE, Brady WE, Palta M. Associations be-
tween antioxidant and zinc intake and the 5-year in-
cidence of early age-related maculopathy in the Bea-
ver Dam Eye Study. Am J Epidemiol. 1998;148:
204-214.
8. Age-Related Eye Disease Study Research Group.
A randomized, placebo-controlled, clinical trial of high-
dose supplementation with vitamins C and E, beta caro-
tene, and zinc for age-related macular degeneration
and vision loss: AREDS Report No. 8. Arch Ophthalmol.
2001;119:1417-1436.
9. Hofman A, Grobbee DE, de Jong PT, van den
Ouweland FA. Determinants of disease and disability
in the elderly: the Rotterdam Elderly Study. Eur J
Epidemiol. 1991;7:403-422.
10. Van Leeuwen R, Klaver CC, Vingerling JR, Hof-
man A, De Jong PT. The risk and natural course of age-
related maculopathy: follow-up at 6½years in the Rot-
terdam Study. Arch Ophthalmol. 2003;121:
519-526.
11. The International AMD Epidemiological Study
Group. An International Classification and Grading Sys-
tem for age-related maculopathy and age-related
macular degeneration. Surv Ophthalmol. 1995;39:
367-374.
12. Klein R, Klein BE, Jensen SC, Meuer SM. The five-
year incidence and progression of age-related macu-
lopathy: the Beaver Dam Eye Study. Ophthalmology.
1997;104:7-21.
13. Goldbohm RA, van den Brandt PA, Brants HA, et al.
Validation of a dietary questionnaire used in a large-
scale prospective cohort study on diet and cancer. Eur
J Clin Nutr. 1994;48:253-265.
14. Klipstein-Grobusch K, den Breeijen JH, Gold-
bohm RA, et al. Dietary assessment in the elderly: vali-
dation of a semiquantitative food frequency
questionnaire. Eur J Clin Nutr. 1998;52:588-596.
15. Dutch Food Composition Table [in Dutch]. Rev
ed. The Hague, the Netherlands: Voorlichtingsbu-
reau voor de Voeding; 2001.
16. Van Leeuwen R, Ikram MK, Vingerling JR, Wit-
teman JC, Hofman A, de Jong PT. Blood pressure, ath-
erosclerosis, and the incidence of age-related macu-
lopathy: the Rotterdam Study. Invest Ophthalmol Vis
Sci. 2003;44:3771-3777.
17. Ott A, Breteler MM, van Harskamp F, Stijnen T,
Hofman A. Incidence and risk of dementia: the Rot-
terdam Study. Am J Epidemiol. 1998;14:574-580.
18. Willett W. Nutritional Epidemiology. 2nd ed. New
York, NY: Oxford University Press; 1998.
19. Seddon JM, Rosner B, Sperduto RD, et al. Di-
etary fat and risk for advanced age-related macular
degeneration. Arch Ophthalmol. 2001;119:1191-
1199.
20. Crabb JW, Miyagi M, Gu X, et al. Drusen pro-
teome analysis: an approach to the etiology of age-
related macular degeneration. Proc Natl Acad Sci
USA. 2002;99:14682-14687.
21. Taylor HR, Tikellis G, Robman LD, McCarty CA,
McNeill JJ. Vitamin E supplementation and macular
degeneration: randomised controlled clinical trial. BMJ.
2002;325:11.
22. Mares-Perlman JA, Klein R, Klein BE, et al. Asso-
ciation of zinc and antioxidant nutrients with age-
related maculopathy. Arch Ophthalmol. 1996;114:
991-997.
23. Smith W, Mitchell P, Webb K, Leeder SR. Di-
etary antioxidants and age-related maculopathy: the
Blue Mountains Eye Study. Ophthalmology. 1999;106:
761-767.
24. Flood V, Smith W, Wang JJ, Manzi F, Webb K,
Mitchell P. Dietary antioxidant intake and incidence
of early age-related maculopathy: the Blue Moun-
tains Eye Study. Ophthalmology. 2002;109:2272-
2278.
25. Cho E, Stampfer MJ, Seddon JM, et al. Prospec-
tive study of zinc intake and the risk of age-related
macular degeneration. Ann Epidemiol. 2001;11:328-
336.
26. Miller ER III, Pastor-Barriuso R, Dalal D, Riem-
ersma RA, Appel LJ, Guallar E. Meta-analysis: high-
dosage vitamin E supplementation may increase
all-cause mortality. Ann Intern Med. 2005;142:
37-46.
27. Klaver CC, Wolfs RC, Assink JJ, van Duijn CM,
Hofman A, de Jong PT. Genetic risk of age-related
maculopathy: population-based familial aggregation
study. Arch Ophthalmol. 1998;16:1646-1651.
ANTIOXIDANTS AND AGE-RELATED MACULAR DEGENERATION
©2005 American Medical Association. All rights reserved. (Reprinted) JAMA, December 28, 2005—Vol 294, No. 24 3107
on March 5, 2008 www.jama.comDownloaded from
