Fish Oils/Omega-3 Fatty Acids

Fish Oils/Omega-3 Fatty Acids - adapted from a handout from the Penn State Heart and Vascular Institute

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What are they? Fish oils contain two Omega-3 fatty acids - eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A third less potent kind of Omega-3 fatty acid is alpha-linolenic acid (ALA), which comes from soybeans, canola, walnuts, flaxseed, and oils made from those beans, nuts and seeds. And although the body can make EPA and DHA from alpha-linolenic acid (ALA), this change is believed to be inefficient in many people. This is why we don’t recommend these beans, nuts and seeds, and their oils as treatment – though they are healthy to eat and to cook with.

What do they do? Fish oils have a protective effect on the heart and blood vessels. In fact, they decrease risk of sudden death, irregular heartbeats and non-fatal heart attacks and strokes. Although the mechanisms responsible for Omega-3 fatty acids’ reduction of heart and vascular risk are still being studied, research has shown they:

  • Decrease triglyceride levels (one of the "bad" fats in the blood)
  • Decrease thrombosis (blood clots)
  • Decrease growth of atherosclerotic plaque (the cholesterol deposits that can clog vessels)
  • Improve arterial health
  • Lower blood pressure

How to increase the intake of Omega-3 fatty acids? The FDA issues advisories on which fish are safe to eat. In general, older, larger, predatory fish such as shark, tilefish, swordfish, and king mackerel may contain larger amounts of mercury, PCBs (polychlorinated biphenyls), dioxins and other environmental contaminants. Smaller fish tend to have one-tenth to one-third the amounts of contaminants of the larger fish.

For most people the most efficient way of consuming Omega-3 fatty acids in amounts that will optimize their benefits is through supplements. Most fish oil supplements tested (for instance by are found to have safe levels of mercury and PCBs.

Components of Selected Fish Oil Products

Brand Amount of EPA & DHA (mg per capsule) Cost* # of capsules per day Website
GNC fish body oil 180/120 $6 3-4
Natrol Omega-3 complex 180/120 $6 3-4
Twinlab Omega-3 234/125 $15 3
Mega Twin EPA^ 600/240 $15 1-2
OmegaRx^ 400/200 $25 2
Ultimate Omega^ 350/250 $27 2
TriOmega^ 500 (total) $20 2
Kirkland Fish Oil# 180/120 $5 3-4
Nature Made Fish Oil# 216/144 $7 3-4

* One month supply, supplying 1g of EPA/DHA.
^ Pharmaceutical grade or makes claim regarding manufacturing process.
# United States Pharmacopia-branded

From Robert Oh, MD. Practical Applications of Fish Oil (Omega-3 Fatty Acids) in Primary Care. J Am Board Fam Pract. 2005; 18 (1): 28-36.

How much Omega-3 fatty acids should a person take?

American Heart Association (AHA) Recommendations for Fish Oil*

Patient Population Recommendations
Patients WITHOUT documented cornoary heart disease Eat a variety of (preferably fatty) fish at least twice a week. Include oils and foods rich in linolenic acid (flaxseed, canola, and soybean oils; flaxseed and walnuts).
Patients WITH documented cornoary heart disease Consume approximately 1g of EPA+DHA per day, preferably from fatty fish. EPA+DHA supplements could be considered in consultation with the physician.
Patients who need to lower triglycerides 2-4g of EPA+DHA per day provided as capsules under a physician's care.


Patients taking more than 3 grams of Omega-3 fatty acids from supplements should do so only under a physician’s care. High intakes could cause excessive bleeding in some people.

Fish oil usually comes in 1000 mg soft gel capsules, which normally contain 180 mg of EPA.

Check the label for the amount of EPA! While the ideal amount to take isn't clear, we prescribe anywhere from 360 to 2160 mg of EPA per day. See below for your prescription.

What about side effects? Fish oils are generally well tolerated, but some patients may have initial mild stomach bloating, and burping up a “fishy taste”. Freezing the capsules before taking them may minimize those side effects. There are also “deodorized” versions of the capsules that may help. Very rare are  stomach pain, diarrhea, severe nausea or vomiting, muscle pain or excessive bleeding. Report these if you experience them.

Any special precautions? Let us know if you have gallstones, liver disease, or severe kidney disease. If you are taking Coumadin®(warfarin), you might need more frequent blood tests in the early stages of therapy, as very high intakes of fish oil may result in you needing less Coumadin®. And remember to inform us if you start on Coumadin®.

How much should I take? You should take your fish oil capsule(s) with meals. Remember to check the EPA dosage on the label and don’t let the “serving” size trick you; sometimes the label will list a “serving” as two pills.

If the EPA per pill is 180mg, our recommendation for you is to START with one capsule daily for two - three days; then

Take __ capsule(s) twice daily for one week, then
Take __ capsules(s) twice daily for one week, then
Take __ capsules(s) twice daily for one week, then
Take __ capsules(s) twice daily for one week, then
Take __ capsules(s) twice daily and continue.

We may adjust the dose based on your blood tests. If the fish oil is well tolerated, after two - three days, you may advance to the next step before a week is complete. If you are having troublesome side effects, go back two steps for a week, and then advance the dose only one step if tolerated. Try to take as much fish oil as you can. Use any techniques you find best (e.g. taking before or with your meals or at bedtime).

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