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Frank A. Bures: Possible fish oil benefits for eyes

April 1, 2018 GMT

I was asked a question about the need or benefit of fish oil for vision because the person had been instructed by an ophthalmologist to take the fish oil because it was “good for eyes.” How is it good for eyes? Good question. Here’s a stab at the answer (no reference to avoid running with something sharp that would put your eye out.)

There is some pretty good evidence that fish oil can relieve some symptoms of dry eye. Whether it can influence age related macular degeneration (ADM) is less clear. Claims in general are that the so-called omega fatty acids in plants and fatty fish contain multiple health benefits, including lowering heart disease risk (not for this discussion) and reducing chronic inflammation to alleviate several serious conditions like cancer, stroke, osteoarthritis, and Alzheimer’s. A smidge miraculous, wouldn’t you say? No mention was found about preventing or slowing cataract or other eye problem development.

Fish oils — and the fish — contain omega-3 fatty acids. Flax seed, a nutritional poster child, contains omega-6 fatty acids. Omega acids are some of the fatty or lipid compounds that are part of all cell membranes. A fatty acid is a compound with a long chain of 16-24 carbons or those c letters in a line. The last one is the omega c, from the last letter, omega, of the Greek alphabet. These are polyunsaturated fatty acids (PUFA) because they have three or more double bonds in the carbon chain. (Getting all nervous like a test is coming?) In the plant PUFA the first one is six carbons from the omega c, and in the fish ones it’s three carbons from the end. Thus, the labels omega-3 or -6. (We’re through the hard part.)

The main omega-3 PUFAs in fish are DHA acid (docosahexaenoic acid) and EPA (eicosapantaenoic acid). The plant omega-6 PUFA is ALA (alpha linolenic acid). We humans cannot synthesize these very necessary compounds, and must consume them from a food source. Hence, they’re considered “essential” food stuffs (like chocolate?). The fish ones can be formed from the flax ALA, in our cells, but not very efficiently. Omega-3’s are considered to be more anti-inflammatory than ALA.

Dry eye is a confusing subject because SO many people experience it as they “mature.” It is considered a result of something causing inflammation in the tears glands. One reference from a Mayo Clinic dietician discusses fish oil relieving symptoms of dry eye rather positively, as do other references.

Another 2012 technical reference from a Harvard ophthalmologist discussed DHA and EPA favorably on a molecular level. He cites newer research in the last 5-10 years that has founds other anti-inflammatory compounds metabolized from DHA and EPA, called resolvins. (Someone must stay up late concocting these names.)

The fish that contain a lot of these omega-3’s are catfish, halibut, salmon, striped sea bass, albacore tune, and anchovies. Many opinions believe these provide a more usable source than the capsule supplements. The nay-sayers bring up the argument that fish may contain unhealthy amounts of mercury. Pick your poison.

Whether fish oil slows developing age related macular degeneration (AMD), is also not resolved yay or nay, Currently, the opinion is it has no positive influence according to studies from the National Eye Institute of the NIH in Washington. These were designated Age Related Eye Disease Study (AREDS and AREDS2. You see these initials used on eye supplements sold over the counter.) Certain vitamins like zinc, vitamin C, vitamin E, copper, and two nutrients found in large amounts of green leafy vegetables, lutein, and zeaxanthin (LOO-teen, ZEE-ah-AAN-theen) are the AREDS2 recipe.

But another paper from 2015 compared the 2013 nutritional AMD treatment study 2, NATS2, to the AREDS, and found positive results from fish oil slowing new blood vessel formation in wet age related macular degeneration which is good. (Is that good or bad?)

On the Mayo Clinic dietician reference one comment was posted at the bottom. The person wrote: “I have a winter and summer residence and PCPs (primary care providers) at both (and good insurance, I hope). One increased my fish oil intake to 3,000 mgs and added vitamin D3, while the other took me off both. What am I to believe?”. There was no reply written ... .

There really doesn’t seem to be a clear answer about absolute ocular benefits. Consult with your doc, whom you trust. Maybe just go fishing more, and try not to be like the health nut lying in bed, dying, but not knowing from what?