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Fish oil and omega-3 fats:
How to be safer with your supplements.


Everyone knows that fish oil is awesome. It’s full of omega-3 fatty acids, which do so many fantastic things in the body.

However fish oil has come under fire. Some claim that it could be hurting instead of helping us. That we’re consuming too much. That we’re in danger.

In today’s article, we’ll review the latest research paper that’s confused and bewildered many people. And we’ll help you make sense of the controversy.

[Note: We’ve also prepared an audio recording of this article for you to listen to. So, if you’d rather listen to the piece, click here.]


I have to admit, I’ve been a big fish oil pusher over the years.

I’ve recommended it to everyone from little kids to little old ladies and I’ve taken more than my fair share of the stuff. Recently, though, I started to reconsider.

It all began with a scientific review called “Why Fish Oil Fails”. Here’s the reference, in case you’d like to see what the fuss is about:

Peskin, BS; J Lipids. Why Fish Oil Fails: A Comprehensive 21st Century Lipids-Based Physiologic Analysis. 2014;2014:495761. Epub 2014 Jan 16. Review.

This paper questions whether we need the essential fatty acids from fish in the first place. It also suggests that these fats might be downright harmful.

First, a little background

To get me to question my own faith about fish oil, this research review must have been rock-solid … right? Actually, no. It was terrible. And I’d like to tell you why.

First, let’s talk about the author’s credibility.

In investigating the author, I learned that, years ago, he made unsubstantiated claims about his academic credentials. There were serious legal ramifications. Fines were paid. Reputations ruined.

Not good.

Then there’s the journal itself: It’s possibly less scientifically credible than the author.

For you science nerds out there, the impact factor of this journal — if you can believe it — is zero. (If you’re not sure what I’m talking about, impact factors indicate how important a journal is to the scientific community).

For the sake of comparison, blogs have a scientific impact factor of zero. So does my daughter’s coloring book. The highly respected New England Journal of Medicine, on the other hand, has an impact factor of around 35.

This is something to keep in mind next time you’re doing research. The scientific credibility of a journal, determined by members of the scientific community, matters.

Of course, I’ll point out that the author’s questionable credibility, and the journal’s non-existent impact factor, don’t necessarily prove that the author’s ideas are invalid.

That’s why I’ll base my critique of this paper on the arguments themselves, which were full of faulty logic, an incomplete understanding of the literature, inappropriate analyses, and cloudy judgement.

You may be thinking “If the paper was so bad, why even discuss it at all?” Well, I wanted to give it some attention for two reasons.

First, the media paid a lot of attention to the research paper. It’s sensational and scary and that drives readership. The problem: Their coverage frightened a lot of people unnecessarily. So I wanted to set the record straight.

Also, for all its flaws, the review did bring up a few good questions, including:

  1. Do we really need fish oil?
  2. If so, how much is enough? How much is too much?
  3. Can fish oil, even in low doses, be harmful to health?

These are important questions that too few people consider when making dietary decisions. So let’s discuss them now.

More about the omega 3 fatty acids

Everyone knows omega-3 fatty acids are good for us. And, if you don’t, I think you’d better recognize.

These fats support cardiovascular function, nervous system function, brain development, and all around immune health. Plus a whole lot of other stuff.

When we talk about omega-3s, generally we’re referring to:

  • eicosapentaenoic acid (EPA),
  • docosahexaenoic acid (DHA), and
  • αlpha-linoliec acid (ALA).

EPA and DHA are the omega-3 powerhouses that have been shown to be the most beneficial in all of the research.

ALA, on the other hand, is considered a “parent” omega-3. That’s because ALA has to be converted to EPA and DHA. Only then can these critical fats do their health-promoting work.

In terms of diet, EPA and DHA are primarily available in marine animal sources (i.e. fish). And ALA is available in plant-based sources such as flax, walnuts, chia and hemp.

In the end, when you eat ALA containing foods like flax or chia or walnuts, you’re crossing your fingers and hoping enough of it gets converted to EPA and DHA. (Eating fish and taking fish oil supplements gets you the EPA and DHA directly).


Do we really “need” EPA and DHA in the diet?

The paper “Why Fish Oil Fails” makes the interesting claim that we don’t need to eat EPA or DHA. That’s right: no fish oil, and no fatty fish.

According to the author…

We make all the EPA and DHA we need

The argument goes like this: since your body can convert ALA into EPA and DHA, if you eat adequate sources of ALA, all your essential fatty acid needs will be met.

In other words: eat the ALA and you’ll end up making all the EPA and DHA you need.

Unfortunately, that assumption doesn’t reflect how the human body works. In fact, conversion from ALA to EPA and DHA is surprisingly low. Which means that you’d need to eat unreasonable amounts of ALA containing foods to get a healthy dose of EPA and DHA each day.

Furthermore, I should point out that the “if your body makes it, you don’t need to eat it” argument is a little weak in general.

After all, we can make glucose without eating carbohydrates, many amino acids without eating protein, and many fatty acids without eating fats. Yet, eating specific carbohydrates, proteins, and fats tend to offer health and performance benefits that help us thrive.

So, while the author is probably right, we don’t need to eat EPA and DHA to survive, health is often improved when we get these marine fatty acids in our diet. And since I’m all about thriving, not just surviving, I’m going to make sure I’m getting mine.

However, the author goes one step further to suggest that…

EPA and DHA from fish are possibly dangerous

This is a strange claim because, from a historical perspective, people have been eating naturally occurring foods with DHA and EPA for a long time.

In many cultures around the world, oily fish like salmon and sardines are dietary staples. Heck, even newborn babies get 300 mg of DHA daily from their mother’s breast milk.

Indeed, from my perspective, I haven’t seen any evidence to suggest that omega-3 fats like EPA and DHA from fish are anything but health promoting. Even in cultures that eat a lot of fish, and therefore lots of EPA and DHA, there don’t seem to be any problems.

The author goes one step further to also suggest that fish oil in excess could be dangerous because there’s no way for your body to regulate it. And that’s a fair statement because eating too much of just about anything probably isn’t good for us.

Of course, that brings us to the next question: How much is too much?

How much fish oil is too much?

Let’s say you look to the research, like I did, and decide that some dietary EPA and DHA is good for you. What about the next logical question: Would more be better?

Should you start eating baskets of salmon, sardines, and herring? Probably not. Aside from the fact that a large portion of our fish supply is contaminated with heavy metals and other potential toxins, when it comes to dietary fats, balance is probably more important than anything.

One example of why this matters: Cell membrane fluidity.

It’s interesting to note that the fat you eat ends up embedded in your cell membranes. When you eat more saturated fat, your membranes are built using saturated fats and therefore get “stiffer”. And when you eat more unsaturated fat (including omega-3 fats) the membranes get built with unsaturated fats and therefore get more “flexible”.

Interestingly, cold water fish, like salmon, have a lot of unsaturated fat in their membranes. That acts sorta like anti-freeze. The extra fluidity from the unsaturated fat saves salmon cells from becoming really stiff, brittle and rupturing in cold water.

You can test this out for yourself. Take some lard (saturated) and some fish oil (polyunsaturated) and put them in the freezer overnight. In the morning you’ll find that the lard is rock-solid while the fish oil is still liquid. The same thing can happen in living organisms.

This cell membrane fluidity is important when it’s in balance. Too little fluidity and molecules can’t move into and out of cells as they should. Too much fluidity and the membranes become “leaky”, allowing molecules to pass back and forth unchecked.

We achieve this balance by taking in a mixed diet, one that contains a variety of fats including saturated, polyunsaturated, and monounsaturated. Which is why it seems odd when people object to taking in a few grams of DHA and EPA rich omega-3 fatty acids.

After all, if the average person eats around 100 grams of fat each day and they strive for a balance of saturated, polyunsaturated, and monounsaturated fats, they’d get around 30-40 grams of each kind.

So, think about it: If you’re eating 30-40 grams of polyunsaturated fat each day, 3 grams of EPA and DHA is less than 10% of your polyunsaturated fat intake and just 3% of your total fat intake.

That’s why even conservative groups suggest that intakes of a few grams of EPA and DHA each day are safe and healthy.

For example, the US Food and Drug Administration (FDA) tells us that up to 3 g of EPA and DHA a day is just fine. And the European food safety authority figures that up to 6 g of EPA and DHA a day is completely safe.

For the record, an 8 oz piece of salmon contains about 3.75 grams of EPA+DHA. (So does a tablespoon of fish oil, something like Precision Nutrition’s recommended Super EPA Fish Oil Complex). And, in one research paper, only positive effects were shown with 7.5 grams of DHA supplementation each day.

Salmon filet on a wooden carving board.

The omega-3 index

If you want to get really fancy and determine the exact amount of fish oil best for you, consider testing your omega-3 index.

The omega-3 index is the percent of EPA and DHA combined in the membranes of your red blood cells. This measure gives a picture of your overall omega-3 status. As well as the fluidity of your cell membranes, which we talked about earlier.

The omega-3 index test will also show your level of risk for sudden cardiac death. For example:

  • Below 4% on the omega-3 index = high risk
  • Between 4-8% = intermediate risk
  • Over 8% = low risk.

Find yourself in risky territory and want to increase your omega-3 index? That’s easy: Eat more omega-3 rich fish. Or take a fish oil supplement.

Of course, the results of eating EPA and DHA on your omega-3 index will depend on certain physical factors, like your body weight, age, sex, physical activity level, and starting omega-3 index.

For example, an older woman with a low body weight, low starting omega-3 index, and a high physical activity level would see the greatest increase in her omega-3 index by eating more EPA and DHA.

How much of an index increase is even possible? One recent study found that consuming 1.8 grams of EPA and DHA (combined) each day for 5 months could boost a person’s omega-3 index by over 5%.

In other words, eating a small amount of EPA and DHA daily has the potential to move an individual from high risk to low risk of sudden cardiac death. Huh… less risk of death? Sign me up.

But wait, there’s another concern, specifically with fish oil supplements, that we haven’t talked about yet: Oxidation.

Spontaneous oxidation of fish oil supplements

One of the most compelling arguments in the “Why Fish Oil Fails” paper is that fish oil supplements could actually harm our health if they contain oxidation products.

You see, fish oil is more vulnerable to chemical oxidation than more saturated fats. And when fats are oxidized, their byproducts can do some nasty things in the body.

As the term suggests, oxidation requires oxygen. This means that when fats like those in fish oil are exposed to oxygen they start breaking down.

Other factors can affect oxidation too: The more unsaturated a fat is, exposure to heat, exposure to light, and exposure to metal can all speed up oxidation.

Why oxidation is bad

There are two parts to oxidation: primary and secondary. The details of the chemical reactions aren’t important here but the products are: hydroperoxides, aldehydes and ketones.

Too much of any one of these can be bad, as they have been linked to cancer, inflammation, toxicities, and more.

In the scientific community, there are a few measures that help us determine how much fish oil has oxidized, including:

  • peroxide value (PV),
  • anisidine value (AV), and
  • TOTOX (2 X PV + AV).

And, when it comes to the fish oil in your fridge, the lower of each the better.

As always, there is some debate about what the upper safe limits should be. After all, it’s impossible to totally eliminate these from any oil.

But most people agree on these standards:

  • PV ≤ 10 meq/kg,
  • AV ≤ 20 and
  • TOTOX ≤ 30.

Since you don’t have a lab in your basement, how the heck can you find out if your fish oil is within these safe limits?

Fortunately, a host of independent companies test fish oil. In addition, most manufacturers test their own products as well.

In fact, many will have the results on hand for each lot number they’ve made. To inquire, contact the manufacturer directly. Or check with the International Fish Oil Standards program.

Avoiding oxidation

There are also steps you can take, as a consumer, to protect your fish oil from oxidation.

  1. Buy high quality fish oil with an expiry date and use before that date.
  2. Keep it in the fridge or better yet in the freezer. Fish oil stays pretty stable at 4◦C (temperature of your fridge) for about 40 days and more than 100 days in the freezer.
  3. Get smaller bottles (250-300 mL) rather than big bottles. You finish smaller bottles quicker so less breakdown (oxidation) can happen.
  4. Pump out the air using a wine saver pump (available at kitchen supply stores and wine shops) to remove oxygen from an open bottle.
  5. If it smells/tastes bad (not fishy but ‘off,’ like mushroom, cucumber, or generally rancid or weird), toss it.
  6. Wrap your fish oil with aluminum foil to reduce exposure to light. That is what scientists do in labs to protect chemicals that are sensitive to light.

What you need to know

Keep taking your fish oil and/or eating oily fish.
Don’t let the fear mongers scare you off and prevent you from doing something that’s inherently healthy. Get at least 1 g of EPA and DHA combined each day.

Conservative estimates suggest you can get up to 6 g of EPA and DHA a day safely. And, possibly, for short periods of time, even more. Just be sure to consult an expert to see what’s safe for you.

Make sure the fish you’re eating has a healthy balance of fats.
Not all fish have a healthy balance of fat. For example, farm-raised fish that’s fed a diet high in non-marine foods may contain far fewer omega 3 fats and far more omega 6 fats.

And, of course, even if the fatty acid profile is good, all those environmental pollutants and heavy metals won’t do you any favors. So investigate where your fish comes from, rotate fish sources, and avoid the sources high in contaminants.

If you decide to supplement, make sure your fish oil is high quality.
One advantage of using a supplement is that most supplements have very low amounts of environmental pollutants and heavy metals. But you still need to consider oxidation.

Prior to purchase, check the expiration date and look up the oxidation values from either a third party tester or an in-house report. Check that the chemical products are at or below the following: PV ≤ 10 meq/kg, AV ≤ 20 and TOTOX ≤ 30.

Buy smaller bottles of fish oil.
The small size bottles ensure you’ll finish them sooner after opening. Which means less chance of oxidation over time.

Once you’ve opened your fish oil, keep it in the fridge and use it within 40 days, or keep it in the freezer no more than 120 days. Longer than that and the chances of oxidation go up.

Find your balance

In the end, whenever any particular food or health intervention gets really popular the loudest people end up in one of two camps.

Camp A: This food is amazing! It cures everything! It’s for everyone! And, of course there’s nothing to be careful about!

Camp B: Those idiots! This food can be really bad for you! And I’ve gotta tell everyone! Look out, I’m going to rooftops! Listen for the shouting!

Smart folks, however, end up in the middle.

Yes, the right kind of fish oil can be really beneficial. For the right people. In the right amounts. But caution is warranted. Use the wrong kind of oil, in the wrong amounts, and instead of improving your health you could be increasing your risk.

So take advantage of the strategies outlined here. And try not to freak out next time the media explodes over a new study written by a questionable author in a terrible journal.


Click here to view the information sources referenced in this article.

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