[PHNUTR-L] Omega-3 fatty acids protect eyes against retinopathy

[Kathrynne Holden]

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Public release date: 24-Jun-2007
http://www.eurekalert.org/pub_releases/2007-06/nei-ofa061907.php

Contact: Anna Harper
afh at nei.nih.gov
301-496-5248
NIH/National Eye Institute

Omega-3 fatty acids protect eyes against retinopathy, study finds
Retinopathies may be prevented or lessened by a change in diet

Omega-3 polyunsaturated fatty acids protect against the development and 
progression of retinopathy, a deterioration of the retina, in mice. This 
is the major finding of a study that appears in the July 2007 issue of 
the journal Nature Medicine. The study was a collaborative effort by 
researchers at Children’s Hospital Boston, the primary pediatric 
teaching affiliate of Harvard Medical School, Brigham and Women’s 
Hospital, Massachusetts General Hospital, the University of Goteborg in 
Sweden, and the National Eye Institute (NEI) and National Institute on 
Alcohol Abuse and Alcoholism (NIAAA) of the National Institutes of 
Health (NIH).

Paul A. Sieving, M.D., Ph.D., director of the NEI, said, “This study 
explores the potential benefit of dietary omega-3 fatty acids in 
protecting against the development and progression of retinal disease. 
The study gives us a better understanding of the biological processes 
that lead to retinopathy and how to intervene to prevent or slow disease.”

The researchers studied the effect of the omega-3 fatty acids EPA and 
DHA, derived from fish, and the omega-6 fatty acid arachidonic acid on 
the loss of blood vessels, the re-growth of healthy vessels, and the 
growth of destructive abnormal vessels in a mouse model of 
oxygen-induced retinopathy. The retinopathy in the mouse shares many 
characteristics with retinopathy of prematurity (ROP) in humans. ROP is 
a disease of the eyes of prematurely born infants in which the retinal 
blood vessels increase in number and branch excessively, sometimes 
leading to bleeding or scarring. Infants who progress to a severe form 
of ROP are in danger of becoming permanently blind. There are also 
aspects of the disease process that may apply to diabetic retinopathy, a 
disease in which blood vessels swell and leak fluid or grow abnormally 
on the surface of the retina, and age-related macular degeneration 
(AMD), a disease of the macula, the part of the retina responsible for 
central vision, and a leading cause of vision loss in Americans 60 years 
of age and older.

The researchers found that increasing omega-3 fatty acids and decreasing 
omega-6 fatty acids in the diet reduced the area of vessel loss that 
ultimately causes the growth of the abnormal vessels and blindness. 
Omega-6 fatty acid contributes to the growth of abnormal blood vessels 
in the retina.

To further test the apparent beneficial effect of omega-3 fatty acids, 
the researchers studied mice fed a diet modeled after a traditional 
Japanese diet (more omega-3 than omega-6 fatty acids) and mice fed a 
diet modeled after a traditional Western diet (lower amounts of omega-3 
fatty acids). In addition, they studied mice genetically altered with a 
gene which mammals normally lack that converts omega-6 into omega-3 
fatty acids. They found that the mice with higher amounts of omega-3 had 
a nearly 50 percent decrease in retinopathy.

Omega-3 fatty acids create chemical compounds known as bioactive 
mediators, which protect against the growth of abnormal blood vessels, a 
condition that characterizes some forms of retinopathy. In part, this 
occurs because these mediators suppress a type of inflammatory protein 
called tumor necrosis factor alpha (TNF-alpha). TNF-alpha is found in 
one type of cell, called microglia, that can be closely associated with 
retinal blood vessels.

“The retina has one of the highest concentrations of omega-3 fatty acids 
in the body,” said lead author and NEI fellowship recipient Kip M. 
Connor, Ph.D., a postdoctoral research fellow at Children’s Hospital 
Boston. “Given this, it is remarkable that with only a two percent 
change in dietary omega-3 intake, we observed an approximate 40-50 
percent decrease in retinopathy severity.”

“Our findings represent new evidence suggesting the possibility that 
omega-3 fatty acids act as protective factors in diseases that affect 
retinal blood vessels,” said John Paul SanGiovanni, Sc.D., NEI staff 
scientist and the other lead author of the study. “This is a major 
conceptual advance in the effort to identify modifiable factors that may 
influence inflammatory processes implicated in the development of common 
sight-threatening retinal diseases.”

These study results, SanGiovanni emphasized, are important because they 
provide a reasonable biological explanation for findings from a number 
of human studies on diet and retinal disease, and they identify low-cost 
and widely available nutrient-based treatment approaches that may show 
merit in future research on diseases that damage retinal blood vessels 
and nerve cells.

"The purpose of our study was to discover and describe the scientific 
basis for any possible protective role of omega-3 fatty acids against 
retinopathy,” said Lois E. H. Smith, M.D., Ph.D., senior investigator of 
the study and associate professor of ophthalmology at Children’s 
Hospital Boston, an affiliate of Harvard Medical School. “By identifying 
the fatty acids, lipids and growth factors involved in both the disease 
and protective processes, we hope to translate this work to influence 
the outcome in patients. Our study results suggest that increasing 
omega-3 fatty acid intake in premature infants may significantly 
decrease the occurrence of ROP. This changing of lipids by dietary means 
may also translate to AMD and diabetic retinopathy. If clinical trials 
find that supplementing with omega-3 fatty acids is as effective in 
protecting humans against retinal disease as demonstrated by the 
findings of this study, this cost effective intervention could benefit 
millions of people."

The NEI is currently conducting the Age-Related Eye Disease Study 2 
(AREDS2) that will, in part, assess the effect of omega-3 fatty acids 
DHA and EPA on the progression of AMD. In addition, an upcoming clinical 
trial at Children’s Hospital Boston will test the effects of omega-3 
supplements in premature infants.
-- 
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
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