Is Your Fish Oil Supplement Safe?

Friday Jan 31, 2014 | BY |
| Comments (21)

Fish OIl Supplements

A recent study of fish oil supplements found that 21 of the 30 products had omega-3 levels that varied by over 10% off their label claims, and 15 were 25% off the actual versus claimed content.

It was a bitter cold January in Chicago when I attended an invitation-only conference on biological therapies at Loyola University. As I listened to one brilliant presentation after the next, one got my attention more than the others.

A distinguished professor—who held both MD and PhD degrees as well as being a Jesuit priest—held up a white foam cup, the kind you get for hot drinks at a takeout place, squeezed the amber liquid from several fish oil gel capsules into the cup, set in on a napkin on the table in front of him, and carried on his presentation.

In three minutes, he held the cup up and turned it sideways so we could see through it. It was like a tunnel. The bottom had dissolved and fallen off!

I know no one takes a handful of fish oil capsules. But because omega-3s are so important, especially for those who don’t eat fish or shellfish, it’s good to know what’s in your fish oil supplements!

What Happened?

As fish oil spoils, it generates acidic compounds. Weak acidic compounds, but acidic, nonetheless. The over-the-counter fish oil used by the professor was likely rancid, and therefore strong enough to melt through the cup.

What would that do to your stomach? Fortunately, the stomach lining is built for strong acids that help breakdown proteins and prepare minerals for digestion and absorption.

The professor’s point was well made: do you know what’s in your fish oil?

Health Benefits of Omega-3 Fatty Acids

The main omega-3 fatty acids in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are precursors for eicosanoids, a molecule necessary for life, and are known to modulate inflammation in the body, as well to deliver other health benefits.

The US National Institute of Health’s MedlinePlus provides an impressive list of medical conditions for which EPA is considered useful. Most of these are associated with the ability of omega-3s to dampen inflammation.

EPA also has an inhibitory effect on CYP2C9 and CYP2C19 liver enzymes. At high doses, it may also inhibit the activity of CYP2D6 and CYP3A4, important enzymes involved in drug metabolism. Research suggests it improves the response of patients to chemotherapy.

Some Conditions Helped by Omega-3s

  • Alzheimer’s disease
  • Arrhythmia
  • As prenatal supplementation to improve fetal health
  • Asthma
  • Autism spectrum disorder
  • Brain fog
  • Chronic fatigue syndrome
  • Depression
  • Fatty liver disease
  • Hyperactivity syndromes
  • Lowers triglycerides
  • Reduces incidence of heart attacks
  • Rheumatoid arthritis
  • Schizophrenia
  • Stimulates circulation

Tainted Omega-3 Products

No doubt fish oil has health-giving benefits. If you don’t like taking pills, you can eat more fatty fish like sardines, tuna, and salmon. Fish tend to concentrate toxic end products like mercury, however, and so do fish oil supplements.

A recent New York Times article calls attention to why it’s important to know what’s in your supplements. Not only do supplement consumers have to be aware of mercury-tainted products, but need assurance that they’re getting biologically available—non-rancid—fish oil, and that what’s on the label matches the content in the capsule.

LabDoor, an internet-based independent supplement testing company, analyzed 30 best-selling fish oil supplements, measuring total omega-3 content, EPA and DHA quantities, vitamin D and CLA amounts, as well as methylmercury concentration and total oxidation value.

Total oxidation value (TOTOX) measurement is used as an indicator of marine oil freshness. Besides the TOTOX value, a high quality fish oil product should involve more than one set of parameters in determining the quality or rancidity of marine oil. Natural antioxidants, like vitamin E, are often added to maintain stability over the product’s shelf life.

The results of the LabDoor’s survey was shocking: 21 of the 30 products of the tested had omega-3 levels that varied by over 10% off their label claims, and 15 were 25% off the actual versus claimed content. Total omega-3 (EPA + DHA) content showed significant ingredient variance, ranging from less than 50% to more than 90% versus stated label claims.

Here’s the really bad news—every product contained mercury, with 3 products recording 50% or greater of the allowable mercury content per serving.

The good news was that a majority of products passed oxidation (freshness) assays, with only 1 product recording a TOTOX score above the upper limit and 6 more measuring within 5% of the upper limit.

Pharmaceutical Grade “Next Generation” Versus Typical Consumer Products

I try to steer my patients away from the unregulated supplement marketplace. I know consumer clubs and direct sales companies offer lower prices, but are they better or worse for you?

For my patients, I recommend pharmaceutical grade fish oil using the supercritical extraction process. I want no mercury in the products I recommend. Supercritical extraction boosts biological value and reduces health metals like mercury and arsenic, while guarding against oxidation. Expiration date, and when possible manufacture date, should be labeled on the bottle.

Environmental Impact of Fish Oil Manufacturing Practices

Sustainable harvesting of non-endangered species like sardines, anchovies, and mackerel are better choices for fish oil supplements. Not only are they high in EPA and DHA, but harvesting these fish creates a lower environmental impact on sea life and ocean health. Other sustainable options include using fish and shellfish by-products from the processing of wild salmon and green mussels.

Next generation fish oil production involves 75% less carbon emissions than other methods of fatty acid extraction and purification. I don’t know about you, but I’ll always purchase a product that has lower negative environmental impact.

Criteria For Fish Oil Supplements

  • Next-generation fish oils produced using advanced green technology
  • Solvent-free, supercritical extraction
  • High EPA concentrate for advanced biological support
  • Low temperature, oxygen-free processing to prevent oxidation
  • Stringent purity guidelines
  • Full disclosure labeling
  • Low acidity
  • Low TOTOX value
  • No heavy metals

Does Your Omega-3 Supplement Work?

Because omega-3s are important for heart, brain, and joint health, and help modulate inflammation, it’s important to know if your supplement is working. Besides safety and environmental impact, your omega-3 supplement has to be biologically efficient enough to get into your bloodstream. The best way is to test your omega-3 level in the red blood cells.

In my practice, I evaluate the omega-3 index measured as a percent, as well as the omega 6:omega-3 ratio. For my patients, I want nothing less than optimal. A desirable omega-3 index is greater than 8%, but my patients taking supercritical extracted fish oils are optimal at 10% or higher.

Chart 1from Omega-3 Index.

Are Fish Oil Supplements Dangerous?

High quality fish oil products in dosages less than 3,000 mg daily are considered safe. The higher dosages used to treat a medical problem should be supervised by your doctor.

There are a few studies suggesting that fish oil supplementation increases the risk for prostate cancer. High dosages over long periods of time, without balancing fish oil with antioxidants like vitamin E and selenium, may have a reverse effect on the immune system. Since omega-3s have an anticoagulant effect, combining fish oil supplements with aspirin or anticoagulant drugs is a concern. Other possible drug interactions include high blood pressure drugs and birth control pills.

Action Steps

  • Always take fish oil supplements with food.
  • Add vitamin E to balance the oxidative effect of fish oil.
  • If you have GERD or other hyperacidity condition, take less fish oil.
  • Use pharmaceutical grade fish oil to assure purity and low acidity.
  • Take super critical extracted fish oil for best absorption.
  • Take 1,000 mg of mixed EPA and DHA once daily.
  • To treat conditions like depression, diabetes, or manage inflammation take 3,000 to 6,000 mg in divided dosages daily.
  • Be careful with fish oil supplements if you take blood-thinning drugs. Reduce dosage if you notice easy bruising or reduced clotting time.
  • Get your Omega-3 Index tested.
Dr. J. E. Williams


Dr. J. E. Williams is a pioneer in the field of integrative medicine, longevity, and natural health. Dr. Williams is the author of six books and more than two hundred articles. During his thirty years of practice, Dr. Williams has conducted over 100,000 patient visits. Formerly from San Diego, he now practices in Sarasota, Florida and teaches at the University of Miami Miller School of Medicine, Division of Complementary and Integrative Medicine, NOVA Southeastern University, and Emperor’s College in Los Angeles.

He is also an ethnographer and naturalist. Since 1967, he has lived and worked with indigenous tribes, and spends as much time in the high Andean wilderness and deep Amazonian rainforest as possible. In 2010, he founded AyniGLOBAL, a non-profit organization dedicated to protecting indigenous cultures, environments, and intellec¬tual rights. His current work is with the Q’ero people of the Peruvian Andes, where he teaches Earth-based wisdom and heart-centered spirituality.

For more information:

Follow him on Twitter:


Comments are closed for this post.

  1. jennifer says:

    Which fishoil brands do you recommend?

  2. rox says:

    I just bought Flora 7 Sources. Clean, plant based, vegan.

  3. Karen Bryson says:

    Found your article very interesting. Are you able to recommend a couple of fish oil supplements that you like? I’ve been taking Garden of Life – Oceans 3, but Labdoor did not test this brand.

  4. Catherine says:

    Fantastic article! What brands of fish oil do you use and recommend?
    Thank you

  5. Mary says:

    I have seen several others saying DHA is even more important than EPA.

    Your focus seems to be more on EPA.

    What is your opinion, then?

  6. Dani says:

    I respect renegade health immensely. Therefore I also respect Dr. Williams. However I’m very skeptical of the term “pharmaceutical grade”. The only place I see this is when people are selling supplements. I’ve never been able to confirm what that term actually means. I’ve Searched the Internet for a specific definition and one does not exist. Supplement seller and supposed raw food guru Lou Corona used to use it all the time and his sales pitches. I find it disingenuous therefore when people give health lectures or write articles referring to so called “pharmaceutical grade” products as it’s the same (IMHO) as big food companies calling their products “natural.” There is in fact no scientific or legal definition of the term.

  7. Lilija says:

    Thanks for great info! What do you say about krill oil? Theoretically it should be a better option, because it is a zooplankton, therefore lower in food chain, therefore contains less bio-accumulated pollutants, including heavy metals.

  8. Kym says:

    Thanks, Dr. Williams. Particularly for the link to LabDoor. According to their information, they actually test the products themselves. Hopefully, the results are reliable. I wonder if you have any comments on plant sources for omega-3, etc.? Are marine sources your basic recommendation?

  9. Kris says:

    Please tell us what fish oil supplements you are taking.

  10. Karen says:

    Thank you very much for this interesting article. I wonder if you could let me know what you think of Green Pasture Blue Ice Royal Butter Oil / Fermented Cod Liver Oil Blend? Thank you!

  11. Rhonda says:

    I am wondering about MOXXOR – green lipped muscle oil and if it was a part of this test and if so the results.

  12. Marja says:

    What about omega3 from algae? My husband and I take a product called Opti3 ( It provides 200 mg EPA and 400mg DHA per 2 capsules.
    Fish consume algae so I suppose this is a good source and it is suitable for vegetarians and vegans!

  13. Jody says:

    Can you recommend some trusted brands of fish oils, that meet all the above criteria? I take Nordic Naturals Ultimate Omega…

  14. Beatrice says:

    Please give the names/brands of fish oil supplements that meet your criteria.

  15. Florence Green says:

    I just started taking a cold water fish oil that contains 800mg. EPA and 400mg. DHA
    However, I’m taking several blood pressure pills which I’m anxious to discontinue–Spironolactone, Amlodipine
    Besylate, and Indapamide.
    According to your article, these drugs might not interact well with the fish oil.
    What is your suggestion?
    Florence Green

  16. tessa says:

    So which brands do you recommend?
    Would you suggest the new “Red super krill” they are advertising everywhere these days in drug stores?


  17. winifred rajsic says:

    How about seal oil Omege 3 capsules??? Processed from seals harvested in the western North Atlantic Seal animals kept humans alive and healthy (and warm) for 10,000 years in the Arctic.

  18. Ken says:

    I take Natural Factors, Dr. Murrays, RXOmega-3 Factors and my index is 7.7%. Is this a good fish oil? Which ones do you recommend? When is the best meal to take fish oil?

  19. Ken says:

    Does the vast amount of radiation from Fukushima which is killing polar bears in alaska, starfish in california, affect the quality of fish oil? Strange that the EPA raised the acceptable radiation limit by over 1000 percent. Does anyone really measure radiation in fish?

  20. jasmine says:

    I think, like everyone else…we were expecting some recommended brands at the end of the article.

    Comments are closed for this post.