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Fish Oil

Should I Take Fish Oil Supplements? Benefits and Harms

12 minute read

Topics Covered:

  • Why should I take fish oil?
  • Is fish oil hype?
  • Is fish oil even safe?
  • The one thing you need to see on any fish oil supplement label before buying it.
  • Healthy people can make their own “fish oil.”

Quick Summary:

This article will help you understand what supplement companies don’t tell you about their product: processing can turn beneficial omega-3 fatty acids into toxins. You’ll learn why fish oil hasn’t lived up to its hype and get tips for finding the best fish oil supplements.

Why it’s time to talk about fish oil.

In the late 1990s, doctors learned that oily fish contains beneficial fatty acids not easily found in the food supply and started recommending oily fish and fish oil supplements to their patients. Twenty years later, fish oil became America’s most popular dietary supplement. Eight percent of all US adults are now taking fish oil, which is pretty astounding when you consider that nobody had heard of fish oil 25 years ago and pretty much zero percent of people were taking it. 

Other supplements that are the same idea as fish oil, meaning they’re supposed to have the same benefits and can have the same drawbacks, are krill oil, DHA/EPA, algae oil, and good old-fashioned cod liver oil.

Why would anyone want to take fish oil?

The reason people take fish oil is for the special set of omega-3 fatty acids: DHA and EPA. These letters stand for the chemical names for two specific kinds of omega-3 fatty acids that our bodies need to help control inflammatory reactions, prevent blood clotting, and build healthy cells, especially in our nervous system. 

Marketing claims around fish oil include:

  • Anti-inflammatory benefits
  • Brain building effects
  • Help for dry eyes
  • Helps to prevent AMD (the most common cause of blindness)
  • Helps people with fatty liver
  • Helps reduce pain in rheumatoid arthritis
  • Reduces triglycerides
  • Prevents heart attacks
  • Prevents strokes
  • Prevents the onset of mental disorders in those at risk
  • Prevents Alzheimer’s

That’s a lot of wonderful things! But is it possible that one little capsule could really do all this?

Fish oil: Hype or Scam

A decent question, one that I’ve seen a lot of people asking on google because more and more we’re learning the supplement industry is rife with profiteering bandits—just like the pharmaceutical industry. So let’s take a look at the complete answer to the hype or scam question.

The bottom line is it’s not just hype.

Fish oil’s supposed benefits are not completely fraudulent claims because there is some basis in reality. 

It is totally true that omega-3 fats represent a family of nutrients our body requires but cannot make on its own so we need to eat, drink, or otherwise consume these nutrients in order to be healthy. If we don’t, we’ll be deficient in nutrients and by definition malnourished. When we’re nutrient-deprived and malnourished, all kinds of things can go wrong with our health.

Conversely, if we are malnourished and have developed any of the many medical problems that develop due to lack of the omega-3 family of fatty acids and suddenly start getting plenty, then that one change can reverse many medical problems. This is why the many health claims made by the fish oil supplement companies are not complete fiction. 

Unfortunately, the reality of fish oil supplementation does not come close to the potential.

The reason you should NOT take MOST fish oil supplements.

The sad truth is that most fish oil supplements are actually bad for you.

Multiple studies show that fish oil supplements are loaded with toxins. You may think I’m talking about environmental toxins, like PCBs or mercury, and other pollutants. Those are in fish, too, but that’s not what I’m talking about. The kinds of toxins I’m talking about are actually more harmful than heavy metals and PCBs.

We have to consider that fish oil is a processed food product. We’re not necessarily getting that special omega-3 family of fatty acids that we think we’re getting when we’re taking fish oil instead of eating oily fish. It has to do with the impact of processing on the omega-3 family of fats.

Numerous toxins develop during fish oil processing.

These toxins are not environmental pollutants and don’t exist in fish. After processing, they are present in fish oil in much greater quantity than any environmental pollutants, which makes these toxins a more serious threat to your health. 

If fish oil supplements contained fish oil in the form that nature made it, fish oil supplements truly could work well to alleviate numerous ailments. The reason most fish oil supplements not only fail to show benefits when studied and may do you more harm than good is that very few fish oil supplements contain fish oil in the form that nature made it.

What do I mean by that?

Fish oil undergoes a chemical change during processing. The omega-3 fatty acids in oily fish are very fragile and the process of extracting oil from fish damages the oil. The chemical fragility of omega-3 fatty acids presents a manufacturing challenge that is not easily surmounted and only a few companies currently appear to make the effort to mitigate those technical challenges. The rest are selling fish oil supplements that are actually more likely to be harmful to your health than beneficial.

The image below is from a study that looked at three over-the-counter brands and one prescription brand of fish oil. They measured how many toxins were present in each and presented their results in this graph.

study finds toxic compounds in most popular fish oils
If you’re buying a popular brand of fish oil, you may be getting a belly of toxins. Watch the youtube video below for a more detailed discussion of this image. Image with permission from source:

It shows that three of the four supplements tested far exceed the threshold of acceptable levels of toxin present on a percentage basis in the oil. All three over-the-counter brands exceed the level dramatically.

It also shows that the prescription omega-3, the stuff a doctor has to prescribe and costs about $200 per month (and insurance may pay for it), actually did not have so much toxin that it exceeded the threshold. But it still had some so that just shows you that these omega-3 fatty acids are very very fragile and they break down very easily and even under the best possible controlled environment of a prescription quality lab you still get some toxins.

Why does processing damage fish oil?

The chemical challenge fish oil manufacturers face is called oxidation. Oxidation is the reason fish oil supplementation has not lived up the expectations. Oxidation transforms the beneficial omega-3 into toxins. This poses two problems to you, the consumer.

First, oxidation destroys the beneficial omega-3 fatty acids. Not all of them, but a lot of them. This loss of omega-3 occurs during the normal heating and refining steps that most manufacturers employ to make their fish oil.

Second, oxidation creates toxins. Oxidation chemically changes the beneficial compounds, creating new ones that don’t exist in fish and in some cases wouldn’t exist without the heating and refining steps of processing. Oxidizing fish oil creates many hundreds of new compounds that simply don’t exist to any measurable level in the fish itself, some of which are extremely toxic.

Unless you know what to look for, any fish oil supplement you buy is very likely to contain unacceptably high levels of toxic breakdown products of fish oil with known cell killing, telomere shortening, mitochondrial and microbiome damaging, as well as DNA-mutating properties. This makes most fish oil supplements worse than a waste of money. They really should not be available to consumers because they’re loaded with toxins.

The one thing you need to see on any fish oil supplement label before buying it.

Any fish oil supplement company that’s not a complete fraud will be able to speak to this problem of oil oxidation. What you want to look for in the marketing is that the company specifically mentions controlling for oxidation. The actual language may say “non-oxidized” like the supplement in the image below.

The actual technology that they use is called “supercritical extraction with carbon dioxide.” That’s a mouthful, and it’s not just hype actually that’s a real thing. They use carbon dioxide that they pump in to the processing environment to replace the oxygen normally present in the air. That’s one way you can control oxygenation reactions; you just remove the oxygen.

Make sure to buy fish oils that say this on the label
Make sure to buy fish oils that detail how they control oxidation. Supercritical extraction is not a really unkind form of extraction, but rather a new technology that displaces the oxygen-rich air with CO2 that won’t damage the fish oil.

Keep in mind, that this language is a good sign but it’s not a guarantee. It doesn’t necessarily mean that they actually do control for oxidation and that is because this is an essentially unregulated industry. But it does mean that I wouldn’t touch a fish oil that doesn’t say that it’s “non-oxidized” and ideally they would also say how they ensure it’s not oxidized, as this one does: Supercritical extraction with CO2.

If Your Metabolism is Healthy Your Body Can Make “Fish Oil.”

Not all omega-3 is created equal.  There’s a common form of omega-3 and a very special form of omega-3. Omega 3 is a kind of fatty acid and it comes in different lengths. Lots of plant and animal foods contain shorter omega-3, but the omega-3 in fish oil is unusually long. Our bodies need both the shorter, 18 carbon form and the unusually long, 20 carbon-plus forms.

If your metabolism is healthy, you can elongate any 18 carbon omega-3 fatty acid into a 20 plus carbon omega-3 fatty acid, thus in a sense manufacturing your own fish oil. If your metabolism is not healthy, the enzymes that elongate omega-3 are not functional.

There’s actually a blood test that you can easily get that will give you a good idea as to whether your body can elongate omega 3 fatty acids. I talk about that in the video below as well as the simple blood test you’ve probably already had that will tell you if your metabolism is healthy enough to make its own “fish oil” from ordinary foods containing omega-3.

Why Trust Me?

Here are a few reasons:

  1. I’m an MD and the advice given here on is the same I give my patients. If something works, I share it here. If something doesn’t work, I share that here too.
  2. I studied biochemistry at Cornell U before medical school. That matters becuase the biochemical value of our foods will be altered by processing, and most folks live off processed oils whether they know it or not.
  3. I don’t sell any supplements so I have no conflicts of interest. This website is purely educational and so if the information I give out is incorrect, this website does nothing for anyone.

References and Resources

NIH article on Omega-3 Supplementation

Articles about Toxins in Fish Oil

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Dr. Cate

With over two decades of clinical experience and expertise in genetic and biochemical research, Dr. Cate can help you to reverse metabolic disease and reshape your body.

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