Summer 2001 Issue — Can omega-3 prevent age-related changes in the eye leading to blindness?

Morton Bryhn

R&D Director
Pronova Biocare

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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 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 seldom 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 hypothesized 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 (published 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 prostaglandin's which interact with the preservation of the intra-occular 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 intra-occular pressure.

A placebo controlled clinical study in 40 patients was able to demonstrate improvement of function in those treated with EPA/DHA.

Cellini et al¹ randomized 40 patients with elevated intra-occular pressure (mean value 322.4 +/- 2.6mmHg) to treatment with 1.16g 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 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 questionnaires 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 coworkers² studies 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, 597 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 a 35% lower risk compared to those who 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 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 life 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 acids can offer prevention of a series of degenerative diseases coming into full effect in the elderly population. The evolution of these diseases comprising cardio-vascular 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 cardio-vascular 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-threatening 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.

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