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Can
Omega-3s Prevent Age-Related Changes in the Eye Leading
to Blindness?
By
Morten Bryhn, MD, PhD
3/26/2001
High intra-occular pressure,
glaucoma, is still a major cause of blindness. Initially
there are no symptoms but when visual impairment occur treatment
often comes too late. Early diagnoses and prophylaxis is
essential to prevent blindness.
Glaucoma
is a disease of the eye caused by increased intra-occular
pressure leading to irreversible defects in the retina.
Untreated the retinal changes will inevitably lead to permanent
blindness. Today routine control of the intra-occular pressure
can reveal elevated pressure which then can be lowered by
several well documented pharmaceuticals. Due to early intervention
the prevalence of blindness caused by glaucoma has therefore
decreased.
Still about 50 000 people are blind due to glaucoma in the
US. High intra-occular pressure does not go with any symptoms
and when visual disturbance occur treatment often comes
in too late. It is therefore important to measure the intra-occular
pressure in people aged 50 or more and pay attention to
members of families with frequent occurring glaucoma.
Glaucoma is seldomly seen in Greenland inuites. Omega-3
fatty acids have pressure reducing effects on the eye. This
was demonstrated in a study on healthy individuals using
EPAX 5500TG.
Epidemiological studies in Greenland inuites have shown
a low prevalence of glaucoma compared to the white population
in Europe. Due to the high intake of omega-3 fatty acids
in their diet it was hypothesised that these fatty acids
could induce pressure lowering effects. Animal studies in
rabbits could confirm this theory. In 1997 studies with
omega-3 capsules in 17 healthy individuals at the University
of Copenhagen given 5g daily demonstrated a significant
reduction of intra-occular pressure even if their baseline
values were normal (unpublished results). Even if the mode-of-action
has not been fully revealed omega-3 fatty acids especially
eicosapentaenioc acid (EPA) serving as a substrate for the
production of prostaglandins which interact with the preservation
of the intraoccular pressure could interfere with pressure
regulation in a therapeutic way. A pharmaceutical latanoprost,
a prostaglandin derivative, was recently introduced to the
market based on consistent clinical reports on lowering
of intraoccular pressure.
A placebo
controlled clinical study in 40 patients was able to demonstrate
improvement of function in those treated with EPA/DHA Cellini
et al (1) randomised 40 patients with elevated intra-occular
pressure (mean value 22.4 +/- 2.6mmHg) to treatment with
1.16 g of EPA and DHA (DHA is the second most abundant of
the omega-3 fatty acids) or placebo. Functional analysis
of the retina by so called blue-on-yellow perimetry showed
a statistical improvement in the patients treated with omega-3
fatty acids compared to the controls and also an improvement
in the active treatment group compared to their baseline
values. The authors concluded that treatment with omega-3
fatty acids must be considered a sound supportive therapy
in the prevention and treatment of glaucoma.
Maculopathia
is the leading cause of blindness today. The risk factors
of getting the disease seem to be the same as for developing
cardio-vascular disease, especially high intake of saturated
fat and high cholesterol.
Another age-related disease of the eye is maculopathy which
today is the leading cause of irreversible blindness in
the US. The cause of this disease is unknown but smoking
and other cardio-vascular risk factors have shown statistically
associations with the development of maculopathy.
A study
in 3654 individuals older than 49 years revealed that about
6% had maculopathia. Correlations with parameters from dietary
questionaires revealed that a regular fish intake seemed
to prevent from having the disease while a high intake of
saturated fat and cholesterol predisposed to a higher risk
of getting the disease
Smith and coworkers (2) studied a cohort of 3654 individuals
older than 49 years in order to reveal clinical signs of
senile maculopathy. At the same time dietary questionnaires
were collected to correlate the intake of certain nutrients
with the occurrence of the disease. 229 of the participants
were found to have clinical signs of maculopathy in different
stages of disease development. Correlation with the dietary
intake of the participants in the study clearly showed that
a regular intake of fish (1-3 fish meals per month) prevented
development of maculopathy while a high intake of saturated
fat and cholesterol predisposed to a higher risk of contracting
the disease.
The
Nurses' Health Study from Boston documented that a high
intake of fish lowered the risk of getting maculopathia
by 35% compared to non-fish eaters In the large Nurses'
Health Study from Boston including 42 743 women and 29 746
men followed for almost 10 years, 567 developed senile maculopathy
(3). Fat intake in the study was assessed with a food-frequency
questionnaire. As in the study by Smith total fat intake
was positively associated with risk of maculopathy while
a high intake of fish was associated with a 35% lower risk
compared to those who only seldomly had fish meals.
Conclusions from cohort studies should be treated cautiously
and only be used for generation of hypothesis. However,
these two latter large population studies are showing the
same results indicating a possible solution for prevention
of this degenerative disease of the eye by use of omega-3
fatty acids.
Regular
intake of omega-3 fatty acids may have a prophylactic effect
on the two most common eye diseases leading to blindness:
maculopathia and glaucoma. The principle of using omega-3
fatty acids early in lifte may be very important not only
to prevent these diseases but also other degenerative diseases
caused by sub-optimal lifestyle such as coronary artery
disease and Alzheimer's Dementia. Integrated in our cells
the omega-3 fatty acids have multiple effects on different
organs in the human body.
The three studies presented and other intervention studies
demonstrate that regular use of omega-3 fatty can offer
prevention of a series of degenerative diseases coming into
full effect in the elderly population. The evolution of
these diseases comprising cardiovascular disease, Alzheimer's
disease and now also glaucoma and maculopathy starts probably
decades prior to the generation of symptoms registered by
the individual. In fact early stages of cardiovascular disease
has been documented already in young adults. It is therefore
important for the individual and for the population in general
to induce measures to prevent these disabling and life-treatening
diseases. The principle of prophylactic treatment with omega-3
fatty acids should be introduced early in life to prevent
the development of degenerative diseases which could shorten
life expectancy and severely reduce quality-of-life in the
autumn of life.
REFERENCES:
1) Cellini M, Rossi A and Moretti M. The use of polyunsaturated
fatty acids in ocular hypertension.
Acta ophtalmol Scand 1999;77 (suppl. 229):54-55
2) Smith
W et al. Dietary fat and fish intake and age-related maculopathy
Arch Ophtalmol 2000;118:401-404
3) Cho
E et al. Prospective study of dietary fat and the risk of
age-related macular degeneration
Am J Clin Nutr 2001;73:209-218
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