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DHA for dry eye syndrome

DHA for dry eye syndrome

Many years ago I went through a severe bout of Dry Eye Syndrome (DES). I was at wits end. I live in a dry climate, which didn’t help. I had a test to measure tear production. Result: zero tears. What to do?

Some research pointed me in the direction of omega-3 supplements, so I tried them. The effect was miraculous (to me anyway); I could feel tears flowing into my eyes. It took several weeks of supplements for the extreme redness and inflammation to resolve.

At the time I wasn’t very familiar with the Ins and Outs of omega-3 fatty acids, but I made it my business to learn all I could. Since then, research has shown that omega-3 fats, particularly DHA, are critically important for eye health.

First a review

DHA is one of the three omega-3 fatty acids that are important for human health.

  1. Alpha Linolenic Acid (ALA): found in canola oil, walnuts, flax and smaller amounts in other oils and some foods. The 18-carbon ALA molecule must be elongated (carbon atoms added to the chain) to be metabolically useful. This elongation process is limited in humans. ALA is not typically featured in omega-3 supplements.
  2. Eicosapentaenoic Acid (EPA): 20 carbon chain. Important for inflammation and other metabolic processes. Found in fatty fish like salmon. Omega-3 supplements derived from fish are good sources of EPA.
  3. Docosahexaenoic Acid (DHA): 22 carbon chain, key component of eye and brain tissue and function, and important for nerve function. Typically sourced from fatty fish like salmon or cod liver. Vegetarian DHA supplements are sourced from varieties of algae that produce DHA.

In the eyes, DHA supports the health and integrity of retinal structure and plays a key role in many of the metabolic processes that control vision. It’s critically important for tear production. Tears are made in the Meibomian glands, located in the upper and lower eyelids. Dysfunctional glands fail to produce sufficient tears, leading to dry eye syndrome and other eye problems.

That’s where DHA supplements come in. If you don’t consume much fatty fish, over time you may develop a deficity of DHA, which can impact tear production, among other things. Taking supplements can help. But which supplements? How much? When?

Sorting through supplements

  • Omega-3 supplements are best as gel caps, not tablets. You can also buy liquids you take with a spoon. They’re usually flavored to mask the slightly fishy taste. The main drawback of liquids is that you can’t really travel with a bottle of fish oil. Whether you buy gel capsules or liquid, keep them in the refrigerator.
  • Always take omega-supplements with a meal that contains fat, to promote absorption. No use buying expensive supplements if they aren’t absorbed.
  • You can choose a supplement formulated specifically for eye health, or a general omega-3 supplement. Eye health supplements will likely be higher in DHA, and may have other components, such as nutrients or plant extracts like lutein. General purpose omega-3 supplements will likely have a higher ratio of EPA to DHA, and few or no other nutrients.
  • Some optometrist and opthalmology offices sell omega-3 supplements. Those are likely fine, but you might prefer to shop around. Word of Caution: omega-3 fatty acids are very fragile and susceptible to heat damage. Products that are mishandled or kept too long may turn rancid. Unfortunately there’s no good way to know about rancidity until you open the bottle. Having experienced this, I have a little trick. Pick up the bottle of capsules and give it a little shake. If you don’t hear the capsules rattling around, it may be that they are all glommed together due to mishandling. Pick another bottle.
  • Omega-3 fatty acids in supplements are typically extracted from fish. Several years ago, a process to extract DHA from special types of algae was developed. This type of omega-3 is acceptable to vegetarians and vegans. The catch is that the algae are good at making DHA, but not so good at making EPA. But for people with dry eye, the algae-sourced DHA is a great choice. All such supplements will be labeled as “algae sourced” or “suitable for vegans and vegetarians”.
  • Krill as an omega-3 supplement source? Not in my house.

How much DHA?

There is no official DHA dose recommendation for dry eye. Actually there’s no official daily intake recommendation, period. Your opthalmologist may have a recommendation, based on experience with other patients. In research studies, doses ranging from just over 200 mg/day to over 1000 had some benefit over several weeks to a few months.

Unfortunately these studies don’t always assess whether the DHA was actually absorbed. Another drawback is that omega-3 extraction techniques vary from one company to another. Different supplemental forms of omega-3 fats may be absorbed less effectively.

Supplement dosages are all over the map. One company’s eye health supplement provides over 800 mg. Another company’s eye health formula has 200 mg DHA plus several other vitamins. If dry eye is your concern, the best bet is to find a supplement that provides 300-500 mg DHA per day, whether or not it’s labeled “eye health” or “vision support”. Big doses aren’t necessarily better, although your eye doctor may have a different opinion, depending on your situation.

Omega-3 from food?

Theoretically you can get omega-3 fats from food, particularly fatty fish like salmon, mackerel, herring and sardines.* Along with cod liver oil, these are common in certain countries. But if you don’t eat much of those foods, your intake of DHA will be limited. It’s not present in any plant foods. ALA is found in a few plant foods, but as I noted, it must be metabolized to DHA before it’s useful, and that process is very inefficient in humans.

If you have a tendency to dry eye, you need to think of omega-3 intake as long term, not as a quick fix. DHA, like all nutrients, is used up by various tissues, and needs to be replenished. If you’ve been advised to take a large dose to deal with dry eye symptoms, you could cut back to a lower maintenance dose after acute symptoms resolve. In that case, a general purpose omega-3 supplement providing about 500 mg EPA/DHA total would be appropriate.

*While these fish are assumed to be good sources of omega-3 fats, different varieties of those fish from different locations (or from a fish farm) may have different omega-3 content.