Should You Take Fish Oil?

cod liver oil fish oil

These days, fish oil is all the rage. Everyone has a reason to take some. Depressed? Moody? Anxious? Take some fish oil! At risk for a heart attack? Take some fish oil! Eat too many Omega-6 fats? Take some fish oil! Perfectly healthy? Take some fish oil!

Is fish oil really all that good for you? The answer is complicated. Yes, fish oil can be a helpful supplement. But it should be taken with caution. In this case, there really is such a thing as too much of a good thing.

The Standard American Diet (SAD) has many things wrong with it. Yet in regards to the essential fatty acids, the two biggest dietary sins are:

1) eating far, far too many of them (more than 4% of total calories), and
2) eating the Omega-6 and Omega-3 fatty acids in the wrong ratios (an n6:n3 of more than 4:1).

In light of the second point, many doctors recommend supplementing with extra Omega-3 fatty acids from fish oil. The idea is that by increasing the intake of Omega-3 fats, you’ll get the ratio of Omega-6 to Omega-3 fats in balance. Pretend, for example that in your diet, you consume about 30g of Omega-6 fats and only 2g of Omega-3 fats. That’s an n6:n3 of 15:1. You want to get it down to 4:1 or less, so you supplement with 6g of Omega-3s. Now you’re consuming 30g of Omega-6 fats and 8g of Omega-3 fats, for an n6:n3 of 3.75:1.

The problem with this, of course, is that by “correcting” #2 this way, you run afoul of #1.

Furthermore, regularly supplementing with high doses of fish oil long-term may be dangerous:

Researchers in the 1970s suggested that the high content of omega-3 fatty acids in the diet of the Greenland Inuit may have protected them from heart disease by lowering their cholesterol and triglyceride levels.75 Since then, dozens of randomized, controlled trials have tested the effect of fish oil supplementation on total and cardiovascular mortality…. These studies suggested that about one gram of long-chain omega-3 fatty acids per day may prevent arrhythmia in patients prone to chronic heart failure or in patients recovering from a recent heart attack. They also suggested that long-term use of fish oils for more than four years may actually increase mortality from heart disease and all causes. (source)

Why is that? How can something that’s good for you in the short term be bad for you in the long term? My theory is that in the short term, the better balance of Omega-6 to Omega-3 fats reduces the symptoms of Omega-3 deficiency since the Omega-6 fatty acids are no longer out-competing the Omega-3 fatty acids in the body. Yet in the long term, the excess polyunsaturated fat content of the diet is causing a rise in systemic inflammation. Over time, the excess inflammation leads to the development of heart disease, diabetes, and even cancer.

Furthermore, the low incidence of heart disease among the Greenland Inuit probably has very little to do with the Omega-3s in their diet:

Many other groups eating traditional diets appear to be free or nearly free of heart disease, and a high intake of marine oils is not a universal trait of these diets. The main source of fat for the Masai, for example, is highly saturated butterfat. The inhabitants of Tokelau consume a diet based mostly on coconut and to a lesser extent on seafood, and even the seafood they prepare contains only two percent of its calories as long-chain omega-3 fatty acids.76 The inhabitants of Kitava consume about two percent of their total calories as omega-3 fatty acids,77 which is greater than the amount that Tokelauans consume but much lower than the amount that the Inuit consume. The traditional diet of Crete provides most of its fat as saturated butterfat from cheese and as monounsaturated olive oil, and contains very little fish.78 If we are to offer a hypothesis about what protects all these groups from heart disease, we must first identify what their traditional diets share in common. The most obvious place to start is the complete absence of refined foods. A very high intake of marine oils, by contrast, is a specific peculiarity of the Inuit diet. (source)

So what’s the solution?

In his own summary of this topic, Chris Kresser of The Healthy Skeptic concluded:

That is why the best approach is to dramatically reduce intake of omega-6 fat, found in industrial seed oils and processed and refined foods, and then eat a nutrient-dense, whole-foods based diet that includes fatty fish, shellfish and organ meats. This mimics our ancestral diet and is the safest and most sane approach to meeting our omega-3 needs – which as Chris Masterjohn points out, are much lower than commonly assumed.

Some may ask why I continue to recommend fermented cod liver oil (FCLO), in light of everything I’ve shared in this article. There are a few reasons. First, I view FCLO as primarily a source of fat-soluble vitamins (A, D, K2 and E) – not EPA and DHA. Second, in the context of a nutrient-dense diet that excludes industrial seed oils and refined sugar, and is adequate in vitamin B6, biotin, calcium, magnesium and arachidonic acid, the risk of oxidative damage that may occur with 1g/d of cod liver oils is outweighed by the benefits of the fat-soluble vitamins.

So I still recommend eating fatty fish a couple times per week, and taking cod liver oil daily, presuming your diet is as I described above. What I don’t endorse is taking several grams per day of fish oil, especially for an extended period of time. Unfortunately this advice is becoming more and more common in the nutrition world.

More is not always better, despite our tendency to believe it is.

Well said, Chris! If you’re interested in trying Fermented Cod Liver Oil, check out the listings here.

(photo by bizzzarro)


  1. says

    Thanks for the article. I used to take fish oil supplements years ago, but have since stopped mostly because I’m not good at remembering to take supplement. Now I have a better reason to have stopped. My family has started eating more seafood recently. We used to not eat any fish at all.

    I’m interested in knowing what you think of krill oil too.

  2. says

    I’ve taken fish oil off and on for a number years. I am honestly not looking for long term benefits from it. But rather something to help with the issues I have now. Recently, based on some reading, I’ve doubled the dose I was taking. Suddenly my skin cleared up. I’m 31 and have had bad skin since my early teens (including while taking the lower dose fish oil). I’m pretty shocked since that was not an effect I was expecting. Now other than the fabulous hormone issues I deal with monthly, my skin stays mostly clear(ish).

  3. says

    I am always wary about taking any supplements, since our bodies expect to get nutrients from whole foods, which contain many substances that are not included in the supplement. Our ancestors did not take fish oil capsules, though cod liver oil goes a long way back. We eat fatty fish and fish broth regularly, including the skin, heads, and bones in the broth. This way, we get fish oil in the way our bodies expect.

    We do take fermented cod liver oil, for the vitamins, along with other complimentary foods.

  4. says

    Ok, if I can’t afford FCLO what’s your next idea? My kids (ages 4 and 5) happily take 1 tsp of Carlson’s Lemon CLO. Eldest is diagnosed ADHD and youngest has a few speech delays. I was planning on starting hubby and I on a 1 tsp dose of Carlson’s as well. Now I’m confused and frustrated. Trying to provide the best for my family that I can with what I have to work with. Is it just better to forgo CLO if it isn’t FCLO?

    • KristenM says

      Virginia — Remember that you can get in 1ml of fermented CLO what it takes a tablespoon (or two, it’s been so long since I did the math) of Carlson’s to get, so it generally comes out to be the same price (or cheaper) per dose. If you crunch the numbers and find out that you’d still prefer the Carlson’s, I’d still take it. These fat soluble vitamins are absolutely essential for growing kids!

  5. says

    Thank you for an article that presents the dangers and the whys of those dangers of overdoing supplements. I’m a nurse practitioner and I do recommend taking fish oil supplements to some of my patients, however, I also know the dangers of too much of a good thing. FCLO is a good source of fat soluble vitamins but those too can be dangerous in excessive amounts because they build up in the body. They are not just excreted in the urine like too much Vitamin C would be. So I applaud your rational recommendations. And UI wholeheartedly (no pun intended) agree with your “prescription” to also get rid of all of the processed, refined foods in the diet as the best way to fix the fatty acid balance in our bodies. Whole foods are the best medicine!

  6. says

    Thank you very much on the article. It all makes perfect sense!
    One thing still remains a question, though: why the ‘fermented’ cod liver oil?
    I know about fermentation used in vitamins/food (I currently work with NewChapter products on a regular base), but why should also CLO be F? 😉

    Hope to hear from you, all this is SO opening my eyes even further than they already were…


    • KristenM says

      Nienke — For one thing, fermented cod liver oil is the more traditional option as it helps preserve the oil and reduce oxidation. Yet another benefit is that it’s far more nutrient-dense than regular CLO, with a better proportion of Vitamin A to Vitamin D.

      • Jennifer says

        CLO is either fermented or heat extracted. When you heat extract the oil, most of the A&D, etc. are burned out of the oil. Most companies just add a synthetic form of the D3 and A back in. (the USDA loves this because they can confirm the amounts of A&D) When the company that makes the FCLO did tests of their products, they found that there was not just D3 in the FCLO – there were 100+ different forms of vitamin D (most we don’t even have names for) and 100+ different forms of vit. A. plus all sorts of other vitamins. Talk about co-factors!! if its not fermented, then it is a highly processed product. YUCK!

        • KristenM says

          To clarify — it’s not entirely true. There are still a couple of brands out there that make an entirely raw cod liver oil without synthetic vitamins added back in. Garden of Life’s Olde World Icelandic comes to mind, as does Corganic’s Raw Cod Liver Oil.

  7. says

    Christina beat me to the punch on this, but I just happened to have watched Dr. Mercola’s video about krill oil first thing this morning! I found it to be very interesting. AND it’s available in capsules. I’d so much rather swallow a capsule or two than have to deal with even a quick swallow of something nasty-tasting.

    • KristenM says

      Just so you know, fermented cod liver oil is ALSO available in capsules, as well as in a variety of flavors. So, don’t let that deter you!

  8. says

    I wanted to add that I recently did some continuing education on the use of Omega 3/fish oil supplements. One recent study found that while taking a fish oil supplement while pregnant was associated with a decreased risk of premature delivery, it had no effect on neuro-cognitive development. Their control was vegetable oil capsules. The only difference they found was that female children whose mothers took the fish oil supplements had an increase in speech DELAYS. This was a randomized double blind study. The researchers were surprised by the findings. Other research has shown that there may be a benefit. They still recommend a baseline supplement with 200mg of Omega 3’s daily but concluded that not every pregnant mother necessarily needed to take these. It will be interesting to see if someone duplicates this study and gets the same results. At least they showed a reduction in premature births in mothers who had had a premature birth in the past. It’s something.

  9. says

    This is an interesting perspective on Omega 3 oils. As mentioned, the common belief is that these Omega 3 fatty acids are beneficial. But I guess what you have rightfully pointed out is the importance of having a balance between Omega 3 and omega 6.

  10. says

    I know this comment is really, really late, and I’m not even sure if you’ll read it, but I had a question about PUFAs and n6:n3 ratios. I’ve recently started tracking my diet with CRON-o-meter because I’ve been seeing some weight creep. While I’ve ultimately decided my problem foods are probably sweets, I noticed that my n6:n3 ratio is about 5:1, on average. I eat about 10-11g of PUFA per day, which works out to roughly 5% of my daily calories. So a little high, but not bad for an American, right? For someone who probably only needs maybe <1g of n3 to balance out the ratio, is it worth it to supplement? Or should I just trust that my ratios are probably better than I'm seeing because I use pastured butter and eggs, which have better ratios than CRON-o-meter assumes?

    I do take 2ml of Blue Ice FCLO per day, unless I'm eating canned salmon with the bones (which provides a ton of Vit. D), which helps my ratios.

  11. Mimi says

    I am taking a fish oil supplement now and am thinking of changing to the FCLO…….how much and when do I take it? And liquid or capsules doesn’t matter?

  12. Frazer says

    Where is the discussion of the toxic heavy metals found in just about all fish/ seafood? The balance or ratio of 6-3 omegas can better be served by eliminating most 6s.

  13. Michelle says

    This is an older post, but I’m assuming it’s getting some new light with the recent Facebook post. This article made me reevaluate my decision to take a daily supplement of fish oil. I honestly went to taking fish oil because it’s cheaper and easier than taking FCLO–plus, the liquid form makes me gag terribly (I’m pregnant, which makes it even worse now). I’m against the notion of most supplements, and this one fell into that category because I agree that it’s something the medical and nutritional communities got consumers hyped up about.

    My family and I do eat fatty fish occasionally, but more importantly, my family consumes a lot of grass-fed beef. I’m sure between these two, we get our share of Omega-3’s! We’re also limiting our grain intake and eat only sprouted grains as is.

    Are there any tests anyone is aware of to determine the ratio of Omega-3/-6 your holding (or if you “hold” them at all)? I know you can attempt to keep track, but since the amounts of Omegas in grass-fed beef varies, I would think it would be pretty impossible to tell exactly. I think it’s important to know if there’s an imbalance before adding or taking anything away from your diet.

    No matter, I’m still switching back to FCLO and butter oil–in a pill form since I haven’t been able to down it otherwise! Thank you for the post!

  14. Renee says

    We live in Canada, in the winter I usually take FCLO for the vitamins but in the summer we spend as much time as we can outside and get our vitamin D the natural way 😉

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