July 10, 2006
Fish Lowers Aging Eye Disease Risks
Eat fish and do not smoke if you want to avoid age-related macular degeneration of the eyes.
BOSTON (July 10, 2006) -- Researchers in Boston studied elderly male twins and found that those who smoke or have a history of smoking had an increased risk of developing age-related macular degeneration as compared to those who never smoked. At the same time, those who ate more fish and had diets with higher levels of omega-3 fatty acids reduced their risk of this blinding disease. Their findings are published in the July 2006 issue of the Archives of Ophthalmology.
Researchers at the Massachusetts Eye and Ear Infirmary and Department of Biostatistics at Harvard Medical School studied 681 male twins from the National Academy of Sciences-National Research Council World War II Veteran Twin Registry. To determine genetic and environmental risk factors for AMD, twins were surveyed for a prior diagnosis of AMD and underwent an eye examination, fundus photography, and food frequency and risk factor questionnaires. The study included 222 twins with intermediate and late stage AMD and 459 twins with no signs of the disease.
“Current smokers had a 1.9-fold increased risk of developing AMD, while past smokers had about a 1.7-fold increased risk,” said Johanna M. Seddon, M.D., director of the Epidemiology Unit at the Massachusetts Eye and Ear Infirmary and an associate professor of ophthalmology at Harvard Medical School. “We also found that increased intake of fish reduced the risk of AMD, particularly if they ate two more servings per week. Dietary omega-3 fatty intake was also inversely associated with AMD. This study of twins provides further evidence that cigarette smoking increases risk while fish consumption and omega-3 fatty acid intake reduce risk of AMD.”
The effects of cigarettes are no surprise. Previous studies have shown a beneficial effect of fish for AMD. This study strengthens the evidence for that finding.
The problem: The oceans are getting depleted of fish. We really need genetic engineering done on crop plants in order to make more scalable and cheaper land-based sources of omega 3 fatty acids.
Before concluding that the beneficial effects are strictly due to omega-3 oils, we should determine whether consumption of fresh water fish (which are low omega-3's) has a similar influence.
Both fresh water and deep ocean fish are high in both omega-3's and the amino acid taurine.
A quick google search on "macular taurine" turns up many items purporting to show that taurine reduces AMD incidence.
BTW, a similar, possibly confounding, effect may occur in some heart disease studies, since atherosclerosis seems to be reduced by consumption of fresh water fish.
Flax seed oil is a very good source.
Lou, replace "concluding" with "investing" and you may see the problem with your statement. We can't wait for conclusive proof that the hypothesis under investigation is true before investing in it. Indeed, to study it is to invest in it.
Given the raft of other benefits apparently due to omega-3's it is indeed likely that consumption of fish in the environment of evolutionary adapatation was relatively high, and if there are other substances found primarily among fish that are absent from our post-neolithic diet then there may be other substances, such as you describe. I think it is a safe bet that enhancing omega-3 oils as a matter of health policy is a reall good idea. The worst that is likely to happen is the discovery of additional deficits such as you describe, but since one of the easiest ways to get omega-3 is to grow algae and the easiest way to convert algae into human consumable form is to feed it to fish, I don't think there is much cause to be concerned so long as the fish themselves are eating a natural source of food.
PS: Flax seed oil is not EPA/DHA but a precursor which is an order of magnitude less efficient at conversion to the desired omega-3.
Probably, long chain omega-3's are largely responsible - waiting for conclusive proof is a bad bet.
In the meantime, I would also like to see continuing studies on taurine.
My above comment:
"Both fresh water and deep ocean fish are high in both omega-3's and the amino acid taurine."
was typed too hastily, and is not correct. It should have been:
"Both fresh water and deep ocean fish are high in the amino acid taurine."
So, if fresh water fish consumption protects against AMD nearly as well as deep water ocean fish consumption, another factor present in both, like taurine, may be responsible.