New population study links higher omega-3 intake to 50% reduction in risk of macular degeneration
by Craig Weatherby
Yet another study has apppeared that affirms the potential for fish and fish-borne omega-3s to protect eye health.
Age-related macular degeneration (AMD) is a progressive eye condition in which the central part of the retina becomes damaged.
AMD is by far the leading cause of blindness and vision impairment. It causes central vision to darken and become blurry. AMD can lead to severe loss of vision and blindness.
As the condition develops from the early “dry” stage to the later “wet” stage—in which blood capillaries leak—retinal pigment cells become damaged and destroyed.
Omega-3s in eye function and healthThe omega-3 fatty acid called DHA, found only in algae and fish, plays key functional and structural roles in all human cells, but is especially important to brain and eye function.
Practically speaking, the retina of the eye is a layer of brain tissue that receives energy from light, which it changes to biochemical and electrical signals to the brain, producing the mental phenomenon called “sight.”
The retina uses specialized photoreceptor cells called rods and cones to process light. Rod and cone cells are extraordinarily rich in DHA. A shortage of dietary DHA leads to a shortage of retinal DHA, which in turn reduces visual acuity.
But lack of dietary omega-3s—from fatty fish or fish oil supplements—can bring more ominous threats, like age-related macular degeneration.
Omega-3 DHA in the retina’s cells is used to make a substance called neuroprotectin D1. This substance protects retinal pigment cells from damage and destruction. In addition, DHA itself helps protect the retina’s pigment cells.
These twin protective actions help explain why people who eat fish more than once a week have significantly lower rates of AMD, according to the results of population studies.
For prior research on this topic, see “Fishy Help for Eye Health Affirmed by Aussie Analysis” and “Fish Seen Helping in Fight to Save Sight.”
New study affirms the role of omega-3s in eye healthThe fish-vision connection has been strengthened by yet another population study linking higher omega-3 intake to reduced risk of age-related macular degeneration (AMD).
The findings show that eating one portion of omega-3-rich fish every week may halve the risk of developing the advanced, “wet” form of AMD (Augood C et al. 2008).
A team led by Astrid Fletcher of the London School of Hygiene & Tropical Medicine recruited 105 people aged 65 years with wet AMD, and 2,170 healthy people to act as controls.
They compared the participants’ dietary habits using questionnaires. Only food sources of omega-3—not fish oil supplements—were considered.
People who reported eating at least one serving of fatty fish per week were 50 percent less likely to have wet AMD, compared to people who ate less than one fatty fish portion per week.
As expected, people whose reported diets contained at least an estimated 300 mg per day of either of the two key omega-3s in fish fat—DHA and EPA—were about 70 percent less likely to have wet AMD, compared to participants with lower estimated DHA or EPA consumptions.
(DHA is the key eye nutrient... EPA intake most likely served as marker for intake of DHA, since both omega-3s occur in fish, in roughly equal proportions.)
The study was funded by the European Commission, the Macular Disease Society UK, and the Thomas Pocklington Trust.
Clinical trials needed for confirmation
To date, there have been no randomized clinical trials (RCTs) testing the potential of omega-3s to reduce the risk of AMD.
While meta-analyses of population studies suggest that eating fatty fish twice or more per week—or taking fish oil regularly—may play an important role in the prevention of AMD, medical associations and public health authorities do not yet routinely recommend omega-3s and fish for this purpose.
This failure of medical authorities to act on the clear implications of ample epidemiological and laboratory evidence on the preventive potential of an essential human nutrient seems irresponsible.
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