[PHNUTR-L] Omega-3 fatty acids protect eyes against retinopathy
fivestar at nutritionucanlivewith.com
Mon Jun 25 10:27:19 PDT 2007
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Public release date: 24-Jun-2007
Contact: Anna Harper
afh at nei.nih.gov
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
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 >
"Ask the Parkinson Dietitian" http://www.parkinson.org/
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