Rapid Fire Q&A: Fish Oil Guide Follow-Up

You guys had tons of questions following last week’s Definitive Guide to Fish Oils. Since the back and forth discourse is my favorite part of doing the blog, I’ll see if I can get to all of them. Let me know if I miss anything!

You recommend storing fish oil in the fridge, but how about storing capsules in the freezer? Wouldn’t this be an even better step to take to prevent the oil from oxidizing?

Freezing your fish oil isn’t necessary (the fridge is fine), but it certainly won’t affect the quality in a negative way and I’ve heard that it can reduce those unpleasant fish burps if you have this problem with your brand of fish oils. I guess if you stock up and buy several years’ worth, freezing would be a good idea. Either way, freeze away!

I’m glad you did a primer on fish oil, I’ve been thinking about it lately. But I would have liked info on DHA/EPA ratios and quantities. I have know idea what is a typical or ideal DHA/EPA ratio or how many mg of each I should be taking.

I’d say an ideal DHA/EPA ratio hasn’t been pinned down just yet. I’m not really sure one even exists, to be honest. If you look at the table of DHA/EPA ratios in seafood, you’ll notice that they’re all over the place. Coastal Grok, therefore, wouldn’t have gotten a constant ratio from the real food he was eating. In my capsules, I do a 600mg DHA/900mg EPA ratio, simply because we make EPA from DHA, and I figure giving more of the finished product cuts down on waste in the body. Bottom line: as long as you’re getting a reasonable amount of DHA and EPA, the exact ratio won’t matter too much. I do okay on 600/900, though.

One question I have is this, should one’s intake of supplementary fish oil be adjusted based on the intake of the omega 6 heavy foods or will our bodies just dispose of excess of both once it reaches it’s preferred ratio? And if so is there a “rule of thumb” that would make it easier to get this ratio down?

Definitely. Try to keep a 1:1 ratio between Omega-3s and Omega-6s. A little extra Omega-3 has beneficial effects aside from the ratio stuff, but don’t go crazy with it and start mega-dosing. You don’t want to have super thin blood and bleed everywhere from a little cut.

I echo Drew’s question. Is there a magic ration of grams of Fish Oil to ounces of veggie oil or meat?

Depends on the type of meat or veggie oil. Here’s a list showing the omega ratios of pretty much all of ‘em (per 100g). 100g is about 3.5 ounces. As you can see from the list, you might just want to avoid veggie oils altogether!

I take in about 6.4 grams EPA/DHA of fish oils. Do you think this is bad or overkill? Ive never experienced anything bad (not that I might) and its been close to a year since I upped my dosage.

Are you eating much Omega-6? If yes, keep with it. If not, there’s certainly no harm in lowering your fish oil intake. You might save some money in the process. But hey, if you feel fine…

What is the concentration of DHA/EPA (generally) in say.. Sardines (canned in sardine oil, not olive oil)? I’m just wondering if eating sardines would be “just as good” as fish oil supplements, or would it be too weak to replace them.

A 3.5 ounce serving of canned Atlantic sardine has 500mg DHA and 500mg EPA (and even 500mg ALA, but we don’t do much with that stuff). Sardines are a good source – I like ‘em with horseradish and Dijon mustard, myself.

I eat 100% grass fed Black Angus beef, 0% vegetable oil, (I use coconut and EV olive oil) no processed foods whatsoever, and no sugar at all. I do take Krill oil daily because, well everyone says you need it. But with my diet, do I really need it?What happens if my ratio is 2:1 in favor of Omega 3?

As far as the eicosanoid ratio goes, I’d imagine you’re doing fantastic and don’t really need it. Still, a bit of fish oil does have other benefits, like improved insulin sensitivity and better absorption of protein following workouts – which are nothing to sniff at.

Side Note: On the issue of fish oil vs. krill oil I wrote the following comment in response to a post Tim Ferris wrote awhile back titled “Krill Oil 48x Better Than Fish Oil?” in which he suggests krill oil is superior:

Interesting choice of headline. It’s a bit sensationalist to suggest that krill is “48x” as potent as fish oil. The line you derive that headline from simply suggests that the natural ORAC (antioxidant) capacity of krill is 48x higher than that of fish oil. But no one in their right mind takes either for its antioxidant capacity. For example, when you look at ORAC, the amount of krill Tim takes offers less than 5% of what might be considered the “DV” (or RDA) of antioxidants. We get orders of magnitude more antioxidants from fruits and vegetables (or other supplements). We take krill or fish oil supplements because they are great sources of DHA and EPA. And it that regard, they are virtually identical (subjective reports of diminished PMS symptoms in one study notwithstanding). Furthermore, most fish oil refiners add vitamin E to the oil as an antioxidant to give stability and add shelf-life, so the comparative shelf lives are also similar. I really don’t see one as being “better” than the other…intead, I see two alternative choices, either of which might represent the single best supplement choice you could make if you were only to take one supplement.

I’ve heard that the recommended amount of fish oil you should take is 0.5 grams for every ten lbs you weigh. That means for someone that weighs 170 lbs, they should take 8.5 grams a day. Is this too much?

I haven’t heard that before, and yes, it does sound excessive (unless you’re eating lots of grain fed meat and vegetable oils every day).

Can I get the same benefits from Flax oil? If not, what’s the difference?

You can’t. Some animals can convert the ALA from flax into DHA/EPA, but we just don’t have the machinery for it and most of it gets wasted. Young women have a better conversion rate, but you’d be better off just taking fish oil. Some time back I wrote a post about flax that might interest you.

Is there such a thing as too much fish oil? What if the normal 30:1, omega 6 to omega 3, was potentially reversed? What would the implication of a 1:2, or possibly higher omega 3 ratio be?

Yep. As a few of our other readers pointed out, excess levels of Omega 3 can thin the blood. I wouldn’t worry about it too much, but just be aware of the potential risks. Unfortunately, there’s no magic ceiling on Omega 3 dosage; everyone’s different, and some people can take huge amounts without experiencing bleeding problems. You’ll just have to figure out what’s best for your body (I can just about guarantee a 30:1 Omega 3:Omega 6 ratio is overkill, regardless). Though if you suffer frequent nosebleeds or get into knife fights on a regular basis, you should keep to that 1:1 ratio as best you can.

I hope that answered all your questions. Keep ‘em coming if you have any more!

TAGS:  omega 3s, toxins

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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48 thoughts on “Rapid Fire Q&A: Fish Oil Guide Follow-Up”

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  1. Great info Mark!

    I don’t think I’d agree that krill oil is any better than fish oil either, especially 48 times better! In fact, I’ve read that krill oil is more commonly contaminated with pollutants.

    Personally, I like getting my share of omega-3 from the food I eat and prefer fish oil over capsules because it at least provides the perception of being less processed. 🙂 There’s also less chance of consuming unwanted ingredients that may be in the capsule.

    1. uh….did you say “less chance of consuming unwanted ingredients that may be in a capsule”????

      In case you hadnt heard….MERCURY is rampant in fish. So a capsule that is prepared removing all the mercury and metals is WAY smarter than eating fish. I love fish too….but we will kill ourselves if we eat too much. And very little is currently too much…

  2. I agree. I think the whole Krill oil thing is a scam. Trying to cash in on the money as alot of people are looking into Fish oils as a healthy O3 supplement. I mean besided other benefits from krill oil or what not, just look at the DHA/EPA content. How can it be 48x better if you have fish oil that has the same or more DHA/EPA in it? Or am I wrong?

    I dont eat much O6 stuff except for meat. I eat grassfed beef less than I do store brought though. Kind of pricey!

    Thanks for answering my question and everyone else’s also!

  3. I certainly understand the questions about the relative benefits of krill oil, based on what you’ve said above.

    At the same time, I’ve recommended krill oil to a couple of friends who were already taking fish oil, and they both saw pretty dramatic improvements in a)cholesterol levels and b)inflammation of the prostate.

    Now of course the plural of anecdote ain’t data, but these experiences, and a couple of others, lead me to think there is something else going on with krill oil than is obvious. It may be an absorption issue or something else, for instance.

    1. “both saw pretty dramatic improvements in a)cholesterol levels and b)inflammation of the prostate.”

      Did these friends take krill IN ADDITION to fish oil, or instead of it?

      1. In our case, Krill oil worked well by itself.

        My daughter has been taking Accutane and it raised her cholesterol levels significantly. We did some research and found that Krill oil might help. It did. It brought her cholesterol levels down enough that she could finish the course of medication with great results. (We did, btw, try many alternatives for her acne prior to going that route but unfortunately they didn’t work.)

        I can’t say Krill worked better than fish oil – we didn’t try fish oil as every time she has tried it in the past she’s been turned off by the fishy aftertaste. We bought a high quality Krill oil and have been pleased by the results – and so has her doctor. Since she doesn’t like fish and won’t take fish oil, we will likely have her continue with Krill even after she is done with her medication.

  4. Thanks for addressing and answering my questions, and even including my spelling errors too!

    Good idea including a follow-up. The extra attention to fish oil definitely serves the needs of your exigent PBers.

  5. Thanks for the detailed follow-up. I’ve tried to alter my blood lipid profile by changing my eating habits, and found it to be extremely difficult. This may be helpful.

  6. Is thinning blood the only real concern then for a higher Omega 3 ratio, Mark?

    Because normally I take around 24 grams per day and I haven’t noticed any bleeding problems at all. In fact I just got a deep paper cut on the top of my finger this morning and hardly bled at all. Just a tiny amount and then stopped after I wiped it off. I do eat mainly grain fed meats though sine they are rather hard to find in my area.

  7. I’ve been taking Green Pastures high-vitamin fermented cod-liver oil (CLO) for the past 6 months, which has replaced the fish-oil capsules I used to take. Like Vin (the first commenter to this post) I enjoy the fact that I can taste the oil which helps monitor whether it’s gone rancid (which is much less likely with fermented oil). I also get a lot of good fat soluble vitamins (especially A and D) from the fermented CLO. And I take 1/2 teaspoon daily of the CLO with a 1/2 teaspoon of high-vitamin butter oil in true Weston Price fashion. Although there aren’t a lot of studies on fermented CLO as far as I know, there are plenty of testimonials as to its effectiveness to correct or attenuate all kinds of maladies.

  8. Thanks for getting my question in the follow-up, Mark.

    Vin & Aaron, I agree 100% – you can accidentally take a bad capsule, but you’d be hard pressed to swallow some rancid fish oil straight.

    Besides, in a pinch it makes a good thing to take other fat-soluable vitamins and supplements with in lieu of food.

  9. I’ve been eating a lot of shrimp lately and this chart confuses me a bit. Does this mean that one medium-sized piece of shrimp contains those EPA/DHA quantities?

  10. I am also confused by the table… it appears that FARMED salmon has more EPA/DHA than WILD salmon… how can that be? I have read elsewhere that farmed salmon have a bad omega 6: omega 3 ratio due to what they are fed. Any ideas?

  11. Great post, Mark! I’ll take my fish oil regularly. It’s just so easy to forget if you’re not in the habit!

    I posted some primal coconut cupcakes you might be interested in. Can’t wait to get your book!

  12. This may have been addressed somewhere on MDA, but I’m having trouble finding info: what about fish allergies? When I got an allergy test as a teenager I was told that I am “slightly allergic” to fish. Never had an issue with it because I rarely eat seafood of any kind. Do you think I’d have a problem taking fish oil supplements? Would some bother me more than others?

    1. Food sensitivities are usually based on protein. Because fish oil supplements are refined to only contain fat, food sensitivities are usually not a concern. I wouldn’t chance it with a severe allergy (which is not the same as a sensitivity), but otherwise, you can at least give the supplement a try and pay close attention to any reactions that may occur within the next few days.

  13. Don’t want to be the Simon Cowell here, but researcher Patricia Kane and Neil Speight M.D. have run fatty acid tests through Johns Hopkins and found that in fact, a surprising MAJORITY of their patients have omega 3 levels that are waaay too high in ratio to omega 6’s.

    They admit that this is probably due to the fact that the vast majority of their patients have health problems so have probably overdone it with the fish oil/flax…but have case after case after case that has shown that too much Omega 3’s can do more than just thin the blood or cause bleeding problems.

    Quoting: “Over 80% of the Johns Hopkins/Body Bio red cell fatty acid tests performed yearly register with high omega 3s and low omega 6’s…Associated with the distorted fatty acid analysis is a wide array of disorders such as fatigue, irritable bowel, nausea, eczema, headaches, visual disturbance, memory loss, etc.”

    Balance is the key — you need omega 6s and omega 3s to make the good econasoids, and while the majority of Americans eating the fast food / “SAD” diet do in fact eat way too much o-6s, some people may not be getting enough.

    Kane, etc., recommend evening primrose oils, and not borage, because borage is a long chain o6 fatty acid.

    I don’t understand it all, but thought I’d pass on what I’m learning.

    I just received my bottle of Fermented CLO w/Butter Oil today…plus continue to take 1-2 caps of Evening Primrose oil, so will see how this experiment works out.

    Wish I could afford the fatty acid tests, but they’re priced out of my league.

    Best regards,


    1. Hi Kelly, that actually makes a lot of sense, especially considering how widely recommended omega-3 has become. For those of us eating fish and pasture raised meat and avoiding grains and vegetable oils, there’s probably not much need for supplementation, and reducing the need for supplements is more primal. 🙂 I’m a big fan of getting as much nutrition as I can from food rather than supplements.

    2. Kelly & all: Everyone taking omega-3 oils on the advice of everyone advocating pharmacological overdose intake levels of O-3’s will have an IMbalance of O-3 due to ignorance and exclusion of the O-6 that as you now know is even more important than O-3.

      As for borage the problem lies in the stereospecifity of the triglyceride molecule, Here’s a bit from lipid researcher Paul Beatty who studied with David Horrobin:
      “The recently deceased, renowned researcher – Dr. David Horrobin showed us the way. He emphasized balance of Omega 6 & 3’s for their synergy and powerful therapeutic affect. He also warned about the STEREOSPECIFICITY of GLA and other derivatives since the position of the EFA derivative will vary its position in the TRIACYLGLYCEROLS (TAGS) depending on the oil source.

      For instance, GLA in EPO is concentrated in the sn-3 position, while in Borage oil it’s in the sn-2 position. This fact has been overlooked by most of the world. The position dramatically affects the eicosanoid outcome, as does the composition of other components of the oil in affecting enzyme utilization.”

      And from Wikipedia, borage seed oil: “Borage oil may contain the pyrrolizidine alkaloid amabiline,[4][5][6] which is hepatotoxic leading to a risk of liver damage.[1] Patients should use borage oil certified free of unsaturated pyrrolizidine alkaloids.[1] Borage oil may be unsafe during pregnancy because preliminary studies suggest borage oil has a teratogenic effect and that its prostaglandin E agonist action may cause premature labor.[1][7] Seizures have been reported as a complication of ingestion of borage oil in doses of 1,500 to 3,000 mg daily. A specific extraction process may offer purified products with 50%+ GLA content.”

      More info can be found in the Wikipedia article about Interesterified fat, Health effects.

  14. I’m a little late here, but hopefully someone is still paying attention to this post.

    With all the concerns about mercury and other contaminants in actual fish, how is fish oil safer? Isn’t it derived from the same fish that is (supposedly) dangerous to eat?

    Not being cynical, just curious…..

    1. If you choose a reputable fish oil, it will be third-party tested for toxins including heavy metals, dioxins, and PCBs. I use Nordic Naturals, which is third-party tested, although I am sure there are other brands that are just as good.

  15. Yes, I’ve read some articles talking about the mercury contamination in most fish. Does it mean taking too much of it isn’t safe already? Maybe it’s a good thing that I chose krill oil than fish oil.

  16. What is the optimal serving size for a person (myself) working out hard and wanting to maximize the usage of fish oil AND flax oil?

  17. I repeatedly had trouble with fish oil…if I took more than one cap (of Sears’ high dose) every other day I would come close to fainting about 90 minutes after ingesting. No one ever knew why….? Every one just said don’t take the fish oil…?

  18. If you have fish burps, the oil is rancid. Prick a pill with a pin, and taste it. You will know if it is rancid. I recently did this with 10+ brands of fish oils. Nordic Naturals is the clear winner.

    What I want to know is this – If I don’t have any problems taking fish oil on an empty stomach, is that the best thing to do? Is that how it is best absorbed?

    1. I’m also a huge fan of Nordic Naturals. I’ve never had a problem with them, and have noticed that some skin problems I’ve had have disappeared since I started taking 2 capsules of Nordic Naturals Ultimate Omega every day.

  19. This is WAY late, but I just found this article. The Tim Ferriss article referenced here was actually written by Dr. Michael Eades.

    Thanks for another great post (years ago…), Mark.

  20. Weighing in, in case anyone cycles back…they have done some European studies that show Krill oil is specifically indicated for menopausal symptoms and does more than straight fish oil. Anecdotal it may be, but it sure seems that way to me based on my own results.

  21. Hi Mark. Love your site.

    What do you think of Brian Peskin’s work on EFAs and the O6/O3 ratio?

    Is there a blood test you can take to test your ratio?


  22. I have recently started following the primal blueprint and started supplementing with omega 3 fish oil as well. Problem is that I have a history of Ventricular Tachycardia and I have just read a study today that suggests that anyone with a history of arrythmia should avoid fish oils or consult with their doctor before taking it as it may be promote more arrythmias. I know that this wont apply to 99.99% of people who read this but. I’m a bit stuck as to whether there is anything else I can take to balance my omega 3:6 ratios?

    1. https://www.ajcn.org/content/70/3/560S.full
      You may be interested in this article, which Mark Sisson references in a similar post. There is a section about a third into the article called “Effects of dietary fish oil on ventricular premature complexes” with references to the studies. Hope that helps!

  23. Krill is the normal diet for South Pole fish and birds, notably penguins. It is being fished at an alarming rate for human consumption. It seems to me that is one reason for avoiding it

  24. Great info. Anyone have thoughts on maintaining these levels but getting around eating fish due to ethical or just personal reasons?

  25. Dr. barry SEARS, aka the ZONE diet, has been advocating high quality Fish Oil since the 80’s. Long before anyone else had. His research concluded that a high quality fish oil should be a combined 60% EPA/DHA. So, in other words, a 1 Gram (1000 mg) fish oil capsule, should have 600 mg of combined EPA/DHA.
    Most high quality fish oil capsules are at the 60% value and most of those are at or near a 2:1 ratio of EPA:DHA. (400 mg EPA: 200 mg DHA in a 1000 mg FO capsule.)
    Such as LEF, Natural Factors, Zone, etc …

  26. I’ve been taking Cod liver oil off and on for a couple of years now, but after doing some research and reading the link for chriskresser.com that was posted it I think I’m going to be stopping for now. I ran out today so think I’ll see how I go without it for a week or 2.

    I take cod liver oil (seven seas brand in the UK) due to it being a lot cheaper than fish oil (£6 versus carsons fish oil @ £26)
    Listening to my own body I know I find it hard to take the cod liver oil on a continual basis, I take the recommended dosage, around 10ml with meals but the longer I take it the harder I find it to continue and I end up stopping for a few days. There was a time i was taking double this, 20ml per day but cut back a month or 2 ago.
    i have been getting some bad sleepyness after some paleo meals, I’ve been trying to play around with fat intake but am now wondering if taking the cod liver oil with these meals is contributing to/causing it.
    I have also been getting some v bad dizzy spells when I stand up intermitently recently, sometimes I feel like I’m going to faint. I’ve been unsure of what causes it, but thanks to janagram’s comment now Im thinking it maybe the CLO.

    I do eat grain fed meats, some seafood, but no vegetable oils, just lard, coconut oil, olive oil, and some nuts. maybe the recommended dosage on the CLO bottle of 10ml a day is too much for me.

    I hear what is being said about the omega 3 and 6 ratios and about Grok’s ratio, but now it’s time to listen to my body.

    Finally, I think theres some confusion in some articles on the dosing amounts to take. Sometimes they are referring to the amount of fish oil, sometimes they are referring to how much EPA/DHA to take.

    In the recommended dosage of the seven seas cod liver oil, 10ml (2 tsp, approx 10g) there is approx 1.5g of EPA/DHA. Sometimes It’s not clear to me if the recomendation is for the amount of fish oil to take, or the amount of epa/dha contained.

    1. I had the same issues with dizziness and actually fainting once about 2 years ago. It was very worrisome as I had just lost about 25 lbs (calorie-cutting and exercise) and I was 32. I went through a barrage of tests and visits to the cardiologist with no real answers. I was basically told to stay hydrated and stand up slowly. Not that helpful!

      About six months later I went Paleo through a program at my gym and started having the same issues again. The nutrition consultant recommended more fat in my diet. It worked perfectly!

      Now, whenever I start to get dizzy like that again I go over what I’ve been eating, and sure enough, I aren’t been eating a lot of fat.

      Hope that helps.

  27. I don’t really know if Krill oil is better than fish oil, but I do know this: animals such as penguins depend on Krill for a food supply. That supply is being depleted by HUMAN activity, making life more difficult for these animals. It seems like if we have a choice, and fish oil is as good, the right thing to do would be to use the fish oil.

  28. “In my capsules, I do a 600mg DHA/900mg EPA ratio, simply because we make EPA from DHA, and I figure giving more of the finished product cuts down on waste in the body. Bottom line: as long as you’re getting a reasonable amount of DHA and EPA, the exact ratio won’t matter too much. I do okay on 600/900, though.”

    Don’t we make DHA from EPA? I thought the conversion could go both ways but in general EPA is converted to DHA?

  29. Found this from xtend-life.com:
    ” but the main component to look at in terms of dosage is the DHA level. This should be high and higher in ratio to the EPA level. This is because the DHA is the ‘building block’ component. The one on which EPA and other components rely to be able to work properly. DHA is able to convert to EPA should EPA be lacking, as it contains 2 additional carbon molecules, but EPA is unable to do the same as it doesn’t contain enough carbon molecules. So take a look at the DHA level, ensure it is in high dose and higher ratio than the EPA level.”

  30. i have concern over my low intake of fish and good omega 3. like u pointed out in another post, we all wish we can eat wold and fresh and organic and grass fed and so on, but we cant. I need to up my omega 3 but there are so many fish oils out there, different types of fish even. Pls help me and advise what should i be looking for when buying fish oil supplements?