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Molecularly Distilled Fish Oil

written by Vin Kutty

comments 35 comments

molecular distilled fish oil

Molecularly distilled fish oil is the most common type of fish oil.

Here’s why:

Crude fish oil has a lot of gunk. Gunk that we don’t like or need.

Molecular distillation is a technology for getting rid of this ‘gunk,’ although there are newer more expensive purification technologies now.

I spent three years of my life becoming an expert at molecular distillation.

Yep, it’s as boring as it sounds!

But it was my first job out of college and I got to live in sunny Florida. So I really can’t complain. Boring or not, molecular distillation is a powerful technology.

Advantages of Molecularly Distilled Fish Oil

  1. Purity. Molecularly distilled fish oil is the purest.
  2. Concentrated Dose. More Omega-3 per pill.
  3. Less Odor. Less rancidity and oxidation.

Disadvantages of Molecularly Distilled Fish Oil

  1. Cost. It’s a couple of pennies more than crude fish oil

Why buy Molecularly Distilled Fish Oil?

Like I said, crude fish oil has a lot of gunk.

It has Omega-3, the good stuff. But it also has a pinch of mercury and a dash of industrial contaminants like PCB and Dioxins.

The best way to remove pollution from fish oil is to use molecular distillation.

Your Grandpa’s Fish Oil

The old technology simply boiled fish oil in a still. Just like moonshine. And as the oil boiled over, it was separated from harder-to-boil materials like waxes and mercury. It was a crude form of purification.

The old technology worked. Sort of.

It literally cooked the oil and the delicate Omega-3 for hours and sometimes days during the process. It removed most, but not all, of the pollutants.

That’s how they made our parent’s and grandparent’s Cod Liver Oil. Ugh!

New Technology: Molecular Distillation of Fish Oil

With molecularly distilled fish oil, the crude oil is placed under extreme vacuum. Under such high vacuum, it is possible to “boil” the oil at very low temperatures. Fish oil boils well under its normal boiling point when placed under vacuum.

And the contents of the oil are boiled off separately based on their molecular weight.

  • EPA Omega-3 boils over first
  • Then DHA Omega-3 is separated
  • Molecules of mercury, PCB, Dioxins have different molecular weight and boiling points, so they are left behind in the “pot”

Everything is purified molecule by molecule. There is very little mingling of molecules. The nasty mercury molecules stay in one place and the healthy Omega-3 in another.

Now you have pure, concentrated fish oil. And no gunk.

This is why molecularly distilled fish oil is recommended even for pregnant women.

Matter of fact, it’s the only kind you should take if you’re pregnant.

Molecular distillation of fish oil is fast

The process is fairly quick.

So delicate Omega-3 fatty acids are protected from breaking down and going rancid.

Why is fast important?

Well, if fish oil is cooked for a long time, it will not only go rancid, but it will start to form trace amounts of trans fats, which are unhealthy.

Molecular distillation of fish oil produces ultra-pure, refined oil with virtually zero contaminants. So pure that it’s hard to even measure the level of contaminants with modern analytical techniques like gas chromatography or HPLC.

Molecular distillation can remove heavy metals, Dioxins, PCBs and other toxins to BELOW detectable levels for human use.

Another Benefit of Molecularly Distilled Fish Oil

Molecularly distilled fish oil has high Omega-3 content.

The only reason to take fish oil is the Omega-3. So why take unrefined fish oil with 30% Omega-3? Why take the other unwanted 70%?

With molecular distillation, you can reach 50%, 60% or even 90% Omega-3 purity.

Yes, it’s a bit more expensive. Purity has its price. But the benefits of a super-concentrated dose of Omega-3 are priceless.*

Molecular distillation lets you get all the Omega-3 you need in a single dose.

How to Tell if your Fish Oil is Molecularly Distilled

  1. It’s often mentioned on the label
  2. Ask. Call or email your fish oil company.


Molecular distillation of fish oil is used to:

  • Concentrate the Omega-3 in fish oil
  • Purify the oil from contaminants and pollutants
  • Reduce the fishy odor of crude fish oils

Now THAT’S progress!


* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


Join the conversation

  1. Fish oil is really very helpful for pregnant women also…it helps to improve the baby’s health and also provides good nutrition to the baby…

  2. Hi Vin Kutty,

    Can you explain why most of the product of wild salmon oil no need the
    molecular-distilled compare to standar omega 3 fish oil??

    • Hi Fariz – some salmon oils are molecularly distilled or purified using ultra-high vacuum separation, which is basically what molecular distillation is. And other salmon oils are sold in the non-concentrate triglyceride form where you will see very low Omega-3 levels. It’s not a matter of not needing distillation, it’s what each manufacturer wishes to sell. I think salmon oil should be molecularly distilled because salmon tend to have slightly higher levels of heavy metals and impurities since they are large, long-lived fishes higher up the food chain that most fish used in fish oils.
      – Vin

      • Hi, Vin,
        Regarding the salmon oil and molecular distillation issue, I always thought that molecular distillation of salmon oil would “ruin” the natural aspect and omega ratios of the oil, no? Solgar, for instance, tells me that they molecularly distill their wild salmon oil, but when I ask for a COA, they say no, that’s it proprietary info and they can’t give it out. They tell me that they follow the CRN Monograph for fish oils, and to go to the CRN pages and see what that means. They say that is all the info I need. What do you think of all this? Thanks.

        • Hi PJ – I don’t think molecular distillation ‘ruins’ anything at all. Technically, you could keep the ratios of the crude oil if you do not concentrate it.

          • Good to know. Honestly, I think I’d rather have my salmon oil molecularly distilled anyway. A lot safer. So, what about the CRN Monograph (that is now GOED?). Does that really mean anything? And what if a company won’t send you their COA? Does it matter?

            • Hi PJ – the GOED/CRN monograph is the rule book we live by. FYI – GOED stands for Global Organization for EPA and DHA Omega-3 and CRN stands for Council for Responsible Nutrition. They established a guideline with minimum quality thresholds and that is what guides us. Having said that, IFOS standards are a bit stricter. So in the rock-paper-scissor world of quality, IFOS trumps GOED/CRN.

              IFOS is also good for giving open access to Certificates of Analyses (CoA) to interested consumers. You want to know what’s in a our product? Don’t believe me – go to IFOS and see for yourself. Not giving consumers a cert of analysis is not an option any more. May be it was in the 1990s. Not today. People today realize that no one really looks out for your health – not doctors, not pharma or food industry, not government – so you have to do that yourself. Doctors are busy shuffling papers and dealing with insurance companies. And food/pharma companies are busy making money and answering to their shareholders. So who looks out for you, the consumer? NOBODY! This is why services like IFOS, ConsumerLab, LabDoor have sprung up. Third party quality analysis helps you answer questions that the product label does not have to room to. It is scary to realize that you have to take care of your own physical health. It involves education and investigation. You can’t believe everything on product labels – just walk down the cereal aisle at the grocery store (I call it the ADHD/heart attack aisle) – you need a qualified third party to vouch for the product.

              • Wow. So, the fact that Solgar flat out refuses to send me their COA should signal a problem? They just kept telling me, “we don’t give COAs on any of our fish oil products because they contain proprietary info on our purification processes.” Secret stuff, I guess. I told them that it’s great that they “say” that they follow CRN, but I shouldn’t just have to take their word for it; any company can “say” anything they like, but they need to be transparent. When I asked Carlson, they said they didn’t send out COAs either, but then their fish oil products are all on the IFOS in plain view, so I don’t need one. Barlean’s are there, too. I don’t want to diss a company’s product simply because they don’t do IFOS or provide a COA, but… Then again, Solgar is currently owned by The Carlyle Group, and things seemed to have changed. What do you think of their refusal to provide any proof of third-party testing?

                • Hi PJ – companies are not required by law to share certificates of analyses. It’s mostly an internal company policy or culture. You asked for CoA. They said no. Your move.

  3. could you explain how omega-3 in triglyceride form enrcihes in molecular distillation process. I heard about omega-3 enrichment through ethylester process.

    • Hi Tony – by enriches, I assume you mean concentrate. Molecular distillation is a common method of purification and concentration. All fish oil starts off as triglyceride form. To concentrate it, it must be converted to ethyl ester form. Some oils are sold in the ethyl ester concentrate form and others are converted back to triglyceride form using a process called enzymatic reesterification. Lots more about this here:

  4. hello Vin,
    Nordic naturals cod liver oil capsules – they claim to use molecular distillation and also no chemicals. They also provide product in tryglyceride form – using enzymatic reactions??

    You also describe the distillation and removal of heavy metals without the use of any solvent. Other sites mention either hexane or ethanol.

    Could you clarify that a TG product can be made and also not use either chemical solvent. thank you very much.

    • Hi Franco – chemical solvents are not integral to fish oil purification. It is for krill oil, but not necessarily for fish oil. Krill usually uses acetone (nail polish remover) or isopropyl alcohol (rubbing alchohol.) During fish oil purification process, any solvent, even if they are used, is ‘boiled’ off, but with krill, you cannot heat the oil and so some very minor levels of the solvents remain.

      So yes, TG oil can be made without solvents.

  5. Hi go to:
    here they claim the process of molecular distillation uses very high temperatures.In the molecular distillation process, omega-3 fish oils are repeatedly raised in temperature to 200°C (390 °F) to concentrate the EPA and DHA and remove contaminants such as pesticides and heavy metals. When the omega-3 fatty acids are exposed to this heat level, they cook and their molecular structure is altered. Something seems out.

    • Hi Peter – molecular distillation is not a cool (room temperature) process. Yes, it requires heat. 200 C? Well, that might be taking some creative liberty to make their point. Are the Omega-3s ‘cooked and altered’ as you/they state? No. They are heated but not destroyed. The link you provided is for a company that sells a product that they claim is not heated. So it makes commercial sense for them to instill a little fear. There are three options for heat-free Omega-3 purification:
      1. Extraction with solvents. This, unfortunately, does not work very well for concentration and leaves a lot of solvents behind, like in krill oil.
      2. CO2 extraction. This works very well. We are introducing a new product that is made this way. Concentrated at room temperature. See this:
      3. HPLC. This works really well too. But it is expensive and technology is not widely available.

      In the meantime, molecular distillation is the most cost-effective way to get Omega-3 into your body. If the idea doesn’t suit you, I suggest you eat more cold-water fish – about 3 or 4 times a week. Nothing beats eating the real thing!

  6. Thanks a lot for your posts Mr. V, I want to know the quantity of omega 3 nd omega nutrients generally needed in the body daily?

    • Hi Michael – this depends on your diet and health goals. For most people, 1000 mg of Omega-3 per day will do the trick. But if you are eating a standard western diet, you will need more. You will also need more if you’re trying to reduce your blood lipids or reduce inflammation.

  7. thanks Mr. Kutty! I am science man. I remember I did science test on water. When vaccum water under chamber, water is boiled by itself. No heat added. You are right, it is very deep vaccum about 10 torr

  8. thanks Mr. Kutty! I am science man. I remember I did science test on water. When vaccum water under chamber, water is boiled by itself. No heat added. You are right, it is very deep vaccum about 10 torr

  9. Hi,

    Do you know of any cod liver oil that is kosher? My ideal would be Carlson’s (cold pressed, good taste, A-D vitamin ratio, contentment free) but unfortunately its not kosher. Thank you for your answer!

  10. Hi, Vin,
    Since you go on here about how molecular distillation should be the only kind on our shopping lists, how do you figure this statement in with the fact that now OmegaVia uses Supercritical CO2 extraction? Also, Nordic Naturals uses “flash” distillation for their non-concentrated products (they explain on their site that this involves steam and no vacuum, and is very clean and safe, meeting IFOS standards), and that their molecular process involves higher heat with a vacuum and is used for their concentrated products. They say they don’t use CO2 as they don’t see the value as yet. So, what are the real differences between the three processes; flash, molecular, and CO2, and what are the advantages/disadvantages among the three? It gets very confusing for we consumers… Thank you!

    • Hi PJ – that article, believe it or not, was written almost 8 or 10 years ago! That’s an eternity in fish oil purification technology. CO2 extraction was not commercially available for mass market use. Back then, molecular distillation was the latest and greatest. I am not going to change this whole blog, but may include a 2015 addendum one of these days. Formulas change. Blogs become irrelevant. Case in point.

      I will let you discuss Nordic’s techniques with them – I don’t agree with their statement that there is no value in CO2. Their definition of flash appears to be what separation chemists call steam distillation. You add steam to oil and that removes a lot of the water soluble and stinky oxidation byproducts. Makes oil smell much cleaner, but it’s not always a great idea to add water, heat and oxygen to fish oil. Steam distillation is not a concentration process as much as a deodorization process. Some companies do it, others don’t. Flash distillation can also be a quick-n-dirty vacuum distillation to get crude oil to about 50 or 60% purity.

      I prefer CO2 extraction and chromatography without a doubt, if you can afford it. It’s still very expensive. Here, you basically run the oil in counter current fashion with liquid, pressurized CO2. The Omegas dissolve into the liquid CO2 and are easily separated from the CO2, leaving high purity Omegas. All this happens at just above room temps. It’s quick, it’s clean, it’s environmentally sustainable because the CO2 is recycled, it does not expose the oil to heat or other oxidizing agents. It’s brilliant. I love it. The only downside is that it is not cheap and not many companies are equipped to do this.

      • Thanks, Vin! As usual, you are “the man” in this field. I appreciate the detailed explanation. Maybe one day, everyone will use CO2/chrom. for fish oils? Would sure make things easier for consumers to figure out!

        • Hi PJ – there will be many fish oil concentrators who do not feel that molecular distillation can be improved on. There are folks who embrace the ‘why fix when it aint broken’ thought. Also, putting in industrial scale CO2 extraction equipment costs tens of millions of bucks, so you will see molecular distilled oil for a few more decades, especially for lower cost products.

    • Hi Tara – yes, concentrated fish oils have no Vitamin A or D in them. If you find commercial ‘Cod liver oil’ with Vitamin A, it is often added back to the purified oil.

  11. why does the skin smell bad of of someone who takes omega 3 ? how can the bad smell be prevented? or what kind of omega 3 he should take?

    • Hi Dalia – it is possible that you are using rancid (old) oil that is oxidized. A small dose, say 500 mg Omega-3 per day, of fresh product should not cause this problem.

  12. Hi Vin,

    I love your explaination, thank you for making an easy to understand article.

    I want to ask you. Which Omega 3 sources is better, is it from fish liver or the overall part of fish itself?

    • Hi Jaja – it does not matter. Sometimes, using only the liver can give slightly different EPA to DHA ratios. If the whole fish is used, there may be more DHA present. The reason I say that it doesn’t matter is that once the crude oil is purified, you are left with mostly EPA and DHA. The Omegas are purified to a high degree that the part of the fish is almost irrelevant.

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