158
of vegetable and animal fat are associated with a greater
risk of advanced AMD.
In 2008, a systematic review and meta-analysis was
undertaken with the objective of evidencing the role of
dietary omega-3 fatty acid and fish intakes in the pri-
mary prevention of AMD.
This review included three randomised, controlled,
prospective cohort trials
(45,46,47)
, three case-control stud-
ies
(48,49,50)
and three cross-sectional studies
(51,52,53)
.
The results of these nine studies demonstrated that high
dietary omega-3 fatty acid intakes were associated with a
38% reduction in the risk of late AMD (OR: 0.62; 95 %
CI: 0.48-0.82). Eating fish at least twice a week was asso-
ciated with a reduced risk of both early AMD (OR: 0.76;
95% CI: 0.64-0.90) and late AMD (OR: 0.67; 95% CI:
0.53-0.85).
Several other relevant studies evidence this fact:
A prospective study conducted by
Cho et al
. in 2001 evi-
denced a positive association between total fat intake and
incidence of AMD. A diet rich in fat increases the risk
of advanced AMD. Nevertheless, eating fish 4 or more
times a week (fish is a major source of DHA) decreases
the relative risk of AMD by 35%
(54)
.
A case-control study conducted by
SanGiovanni et al.
concluded that higher omega-3 and fish intakes are asso-
ciated with a decreased risk of neovascular AMD
(55)
.
The objective of
AREDS report n. 20
was to evaluate
the association between lipid intake and age-related mac-
ular degeneration severity at baseline. The results of this
study showed that total dietary intake of total long-chain
omega-3 polyunsaturated fatty acids (LCPUFA) was
inversely associated with neovascular (NV) AMD (odds
ratio (OR): 0.61; 95 % confidence interval (CI): 0.41-
0.90), the same occurring for docosahexaenoic acid, a
retinal omega-3 LCPUFA (OR: 0.54; 95% CI: 0.36-
0.80), when the highest and lowest intake quintiles were
compared, after adjustment for total energy intake and
covariates. Higher fish intakes, both total and broiled/
baked, were also inversely associated with NV AMD
(OR: 0.61; 95% CI: 0.37-1.00, and OR: 0.65; 95% CI:
0.45-0.93, respectively). Dietary intake of arachidonic
acid was directly associated with the prevalence of NV
AMD (OR: 1.54; 95% CI: 1.04-2.29). No statistically
significant relationships were found for other lipids or
groups
(56)
.
More recently, in
AREDS report n. 23
, reduced likeli-
hood of progression from bilateral drusen to CGA was
observed in individuals reporting the highest EPA intakes
(odds ratio (OR): 0.44; 95% confidence interval (CI):
0.23-0.87) and EPA + DHA intakes (OR: 0.45; 95% CI:
0.23-0.9). DHA levels were associated with CGA in age,
gender and calorie adjusted models (OR: 0.51; 95% CI:
0.36-1.00). However, this statistical relationship was not
observed in multivariable models. This study suggested
that dietary intake, of long-chain omega-3 polyunsatu-
rated fatty acids, is associated with a decreased risk of pro-
gression from bilateral drusen to CGA
(57)
.
European study Nat-2, performed at the University
of Créteil
, a double-blind, randomised, parallel, com-
parative study, compared oral DHA supplementation
with placebo in the prevention of exsudative age-related
macular degeneration in 298 patients with any type of
drusen in the study eye and wet AMD in the fellow eye.
Nat-2 supplementation consisted of 10 mg of L, 2 mg of
Z, 1 mg of omega-3 (DHA plus EPA), 500 mg of vita-
min C, 400 IU of vitamin E, 25 mg of zinc and 2 mg of
copper. Patients took no other supplements and were fol-
lowed for three years (2004-2008). The first study results
included in NAT-2 report no. 1, revealed high HDL and
low PUFA levels in exsudative AMD patients. These
findings confirmed the benefits of DHA supplementa-
tion in these AMD patients
(58)
.
Two important prospective observational studies clearly
reveal that fish consumption and omega-3 fatty acid
intake decrease the risk of AMD:
The Blue Mountains Eye Study and the Melbourne
Collaborative Cohort Study.
Blue Mountains Eye Study:
The objective of this longi-
tudinal study was to investigate the association between
baseline dietary fatty acids and 10-year incidence of
AMD in an elderly Australian cohort. Nutrient intakes
were estimated through a semi-quantitative food fre-
quency questionnaire.
The risk of incidence of early AMD was lower in indi-
viduals consuming 1 to 2 servings of nuts per week (RR:
0.65; 95% CI: 0.47-0.91). These results were similar
to those obtained for dietary consumption of long-
chain omega 3 PUFAs, which also show a lower risk of
incidence of early AMD in participants eating 1 serv-
ing of fish per week (RR: 0.69; 95% CI: 0.49-0.98).
Participants consuming below-average amounts of lin-
oleic acid contributed the most to this association (RR:
0.57; 95 % CI: 0.36-0.89). Nut consumption was asso-
ciated with a lower risk of pigmentary abnormalities in
non-smokers, individuals with below-average total to
high-density lipoprotein serum cholesterol ratios, and
individuals with above-average beta-carotene intakes
(59)
.
Melbourne Collaborative Cohort Study
: the aim of
this study, carried out in 1990-1994, was to investigate
the relationship between past dietary fat intake and the
