Fish Oil Forms: EE vs. TG Oils – Part 1

Ethyl ester versus Triglyceride form of Omega-3 fish oil

Is one better than the other? Or is it just nerdy hair-splitting?

I’ve had a few questions in my inbox about the difference between different types of fish oils.

No, I don’t mean Cod liver oil vs Salmon oil.

We’re talking molecular structure of the Omega-3 fatty acids.

We’ve talked quite a bit about the Phospholipid (PL) form of Omega-3 found in krill oil.

Ethyl Ester (EE) form and Triglcyeride (TG) form are the most common types of fish oils.

The TG form is naturally found in fish. But it can’t be concentrated. To produce a concentrated pharmaceutical grade fish oil, it is necessary to convert the TG form into EE.

Almost all the pharmaceutical grade oils and prescription Lovaza are in the EE form.

The science suggests that the PL form is likely the best absorbed of the bunch.

PL Omega-3 found in krill makes a lot of sense theoretically because that’s how Omega-3 is stored in our body. But krill oil is a very weak source of Omega-3. And it cannot be concentrated without destroying the PL-Omega-3 bond. If you heat krill oil, you destroy most of what’s good about it.

That’s why krill oil is concentrated (somewhat) using solvents like hexane or alcohol.

Still, there are slight differences in absorption between EE and TG forms of fish oil. Don’t think of this as two losers fighting for second place.

So…between TG and EE, which is better?

TG is a little better, in my opinion. But not much.

Scientific opinions vary.

See table below:

The Science Behind EE vs TG Absorption

Research Results are Mixed




#1Luley et al.No difference between EE and TG.
#2Nordoy et alNo difference between EE and TG.
#3Krokan et alNo difference between EE and TG.
#4Hansen et alNo difference between EE and TG.
#5Harris et alNo difference between ME and TG. But both reduced blood triglyceride equally well.
#6Reis et alNo clear difference.
#7El Boustani et alTG was slightly better.
#8Lawson & HughesTG was slightly better.
#9Dyerberg et alTG was better.
#10Neubronner et alTG was better.

There’s one common element in all the studies where the researchers found no clear difference between EE and TG: study participants took the pills with their meals.

Specifically, the fish oil pills were taken in the presence of some dietary fat.

So if you take EE fish oil with your meals, you will dramatically increase its absorption, to the point that there is virtually no difference between the two forms.

This study showed that eating fish was the best way to get Omega-3 but there was a 3-fold increase in absorption of Omega-3 if fish oil pills were taken along with food.

OmegaVia uses EE fish oil.

This is why our dosage directions clearly say: BEST IF CONSUMED WITH A MEAL.

If taken on an empty stomach, TG is slightly better absorbed.
If taken with a full meal, TG and EE forms are almost equally well absorbed and the above advantage virtually vanishes.

Also, there are no reliable studies where EE dramatically outperformed TG.

Other than that, the differences are minor:

  • TG tastes better than EE, if you want to drink liquid fish oil by the spoonful.
  • TG is the natural form Omega-3, as it is found in fish.
  • TG is slightly more resistant to rancidity.

These are clear benefits if you take liquid fish oil.

The Omega-3 Index

Of the list of studies in the table above, the best designed and most recent is the one by Neubronner et al.

Unlike the other studies, these scientists decided to measure the Omega-3 Index.

I’ll write more about Omega-3 Index at a later date, but in a nutshell, it measures the actual percent of Omega-3 that becomes a part of your red blood cell membranes.

An Omega-3 Index of 8 and above is considered low risk for disease. 4 to 8 is intermediate risk. Below 4 is high risk.

  • Japanese are almost at 9. Not bad!
  • Germans are at 6. So-so.
  • Americans are, ahem, at 4.

In the study, BOTH EE and TG forms of fish oil were well absorbed and BOTH increased Omega-3 Index quickly and significantly after taking about 1,700 mg of Omega-3 per day.

The TG form did a slightly better job than EE form. See below.

Omega-3 Index comparison of EE vs TG fish oil. Adapted from Neubronner et al.
Adapted from Neubronner et al. Enhanced increase of omega-3 index in response to long-term n-3 fatty acid supplementation from triacylglycerides versus ethyl esters Eur J Clin Nutr 65 (2010) 247-254.

Both TG and EE forms of fish oil quickly got the participants from below an index of 8 to well above it. And it looks like it took less than 3 months to do so.

There was a 15% difference in Omega-3 index between TG and EE fish oils at the end of 6 months.

This tells me that the ‘biological outcome’ (translated to English, that means ‘the benefits to your health’) is virtually the same.

In the authors words, the EE fish oil ‘highly exceeded’ the goal of getting the participants above an Omega-3 index of 8. They reached a very healthy index of 12.2.


  • Is that 15% worth the extra cost of TG fish oil?
  • Is all this just nerds splitting hairs?
  • Is there any truth behind the internet fear-mongering?

Find out in Part 2.



This website is for your education and general health information only. The ideas, opinions and suggestions contained on this website are not to be used as a substitute for medical advice, diagnosis or treatment from your doctor for any health condition or problem. Users of this website should not rely on information provided on this website for their own health problems. Any questions regarding your own health should be addressed to your own physician. Please do not start or stop any medications without consulting with your doctor. We neither encourage you to do so, nor can we be held responsible for the fall out of failing to seek the counsel of a medical health practitioner.

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Vin Kutty
Vin Kutty, MS, is co-founder of Innovix Pharma. He is a nutritionist, author, and Omega-3 expert with 20 years of experience.


Join the Conversation

  1. Great information! Thanks for sharing some very useful information on the
    difference between Ethyl Ester and Triglyceride-based fish oils.

  2. HI,

    It’s stated here that OmegaVia uses EE fish oil but on the IFOS consumer report

    listed it as TG capsule. Does this means the same as using TG oils?

    • Hi Tom – our product is made with EE fish oil. The reference to it being a TG oil on the IFOS website is an error. We’ve made them aware of it. Hopefully, we’ll fix it with the test of the next batch, which should be in a couple of weeks.

      – Vin

  3. Vin, what components of blood work are used to determine your omega-3 index. In other words, if I have my blood drawn (a Chem 7, 13, or 21), would I be able to determine my omega-3 index and, if so, which components do I look at?

    • Hi RWM – these are separate questions. The Omega-3 index is based on the Omega-3 incorporated into the red blood cells. You can’t guess that from the normal blood works results.

      – Vin Kutty

          • You learn something new every day. I never heard of this test. I guess you have to submit a blood sample to OmegaQuant. I’ll contact them.

          • Vin, I spoke with OmegaQuant today and got details of the test. Not inexpensive. $150. Will run it by my insurance carrier to see if they will pick up the tab. Thanks for the heads up!

              • I ran this test by my health care provider. The problem is, no one knows much about it. They’ve referred me to a cardio specialist whom they feel might know more.

                I think the problems with this test are twofold: (1) lack of exposure and insufficient knowledge base, and (2) its usefulness, if you don’t have serious heart issues. In other words, is the test important for a reasonably healthy individual?

                • Hi RWM – I assume you’re talking about the Omega-3 index…yes, very few doctors know about it. It is not standardized, very few labs offer it and it is expensive. I’d be surprised if a cardio specialist would know more – fortunately, if you are OK spending the money, you can do it yourself without a doctor’s help. But you may have difficulty interpreting the results without their help. Is it important for a healthy person, no, probably not. But ‘healthy’ people often have high Omega-6 consumption and this could be a red flag to nudge you in the right direction. You’re better off avoiding Omega-6 and taking 2000 mg of Omega-3 per day…and take the test just for curiosity.

                  – Vin Kutty

  4. I see this expression bandied about by the proponents of the triglycerides form of omega-3: “The natural triglycerides form [of omega-3] has been demonstrated to have up to 70% greater bio-availability than the ethyl esters form [of omega-3]”

    Is there any truth to that statement? What are these proponents trying to suggest?

    • Yes, if you use funny math. This is called ‘relative difference.’ Just like major statin drugs claim 50% reduction in heart disease because people using statins had 2% mortality rate and those not using statins notice 3% (I’m taking some liberty with numbers to make my point). Technically going from 2 to 3 is a 50% increase. But in an ‘absolute difference’ perspective, you lowered your risk of mortality by just 1% (nothing!) not 50%.

      The 70% greater bio-availability etc. is usually ‘relative’ difference. Funny math. If you take EE oil with a fatty meal, these differences virtually wash away. TG would still be a tiny bit better, but not worth the 2X premium.

      – Vin Kutty

  5. Interesting!

    I know OmegaVia is in the ethyl ester form. Was that a conscious decision on the company’s part to manufacture it in that form as opposed to the triglycerides form?

    • Hi RWM – yes, absolutely, it was a conscious decision. Every little detail of the formula and product was agonized over. The process took two years. We went with an EE formula after having looked at all the facts.

      – Vin Kutty

  6. Alright, I’ve been reading the rest of your website and I’ve found it to be the best layman’s website. I do reviews for a well known website and I’ve spent a lot of time reading up on O-3, including the actual studies. You have by far done the best summary of the studies and the analysis on the web, even down to stating that some of the studies were paid for by companies that made the oils. My hat’s off to you, sir!

    • Hi RWM – a ‘fatty’ meal is anything with some fat in it. Orange juice and toast is NOT a fatty meal. Skim milk over cereal is NOT a fatty meal. Eggs and bacon, yes. Omelette, yes. Steak and veggies, yes. Generally, most of us need more healthy fats and less protein and carbs in our diet.

      – Vin Kutty

  7. Hi, Vin Kutty, I followed RWM here from Amazon. I was reluctant to even look at this page at first because, being a company that sells fish oil, I thought you’d be biased… but I think you’ve proved yourself unbiased with all the info presented and your willingness to answer questions. I’m impressed.
    My question: Doesn’t the natural form have more beneficial natural compounds (like antioxidants) than the EE form? How important are those natural compounds? For example, should I simply be looking for antioxidants elsewhere, like with green tea extract supplements, and only stick with fish oil for the omega-3s?

    • Hi Benjamin A – thank you. I don’t claim to be unbiased because I am somewhat biased…in that I love the product we make and if there is something I or our customers don’t like about it, we simply upgrade the formula to our mutual liking.

      Concentrated forms of TG fish oil do not have any additional ingredients. Some low-potency salmon oils and cod liver oils have other ingredients like astaxanthin or Vitamins A and D, but these are not concentrated oils. Some people take fermented Cod liver oil because of these other nutrients. All this is trying to solve a nutrition problem by taking pills, to be honest. I prefer to get my Omega-3 from both fish and supplements. If you’re looking for the other ingredients, then go straight to the source – fish! If you want antioxidants, you should be eating a diet rich in fresh vegetables, fruits, grass-fed meats, wild-caught seafood, nuts and eggs. If you don’t/can’t eat fish, well, then supplements are your choice.

      The purpose of EE oil is to give you a very high level of Omega-3 per pill. And from that perspective, EE oils deliver.

  8. I have heard that the TG type of fish oil is better if you have more digestive issues….is this true? I am also hearing that the TG helps you to moderate your hormones and lose weight better than the EE type.
    Can you please comment on this. Also does enteric make a big difference? I am hearing that if it is enteric coated…that the results are 300 times better than if not. As a mom to autistic kiddos….fish oil is a biggie. And since mom is a overweight….it would be nice to get a twofer!!!

    • Hi Ronni – I have not heard these things…and these claims have not been proven by research. Marketers selling TG fish oil will say anything to make their product appear better and make EE appear like poison. Oh well. Truth is, TG is slightly better absorbed if taken on an empty stomach. If EE is taken with meals, the differences virtually vanish.

      Enteric coating makes a difference in taste/burping etc. There is also some evidence that says it is better absorbed. But definitely not 300 times better.

  9. HI There,
    I love your blog! Do you happen to have the full references from your chart in the above post?

    • Hi Louise – please click on the names of the authors on the table – the author’s names are linked to studies where available. Thanks.

  10. Hi Dr Vin : I have three concerns regarding Omega fatty acids:
    First off, you must have heard about that medical study in Seattle that claims that Omega acids may increase Prostate Cancer incidence…what is take on this???
    Secondly, is Omega 3 dose of 1000mg is enough or better supplemented with Omega 6 and 9??
    Last, can fish oil capsules get rancid as some people claim and that it is tested by fishy burps???

  11. Hi Vin,
    the omega 3 we ingest are taken from fish and are in Tg forms when in the fish but obvioiusly these fish must be also getting them from somewhere if so where do they get it from and wouldnt it be much easier to manufacture omega 3 from where the fish gets it from and ingest it in its pure form in high concentrations?

    • Hi Jojo – yes. Fish get it from algae and further down the food chain. There are companies that cultivate algae and harvest Omega-3 from algae. Sooner or later, we will eat all the fish in the oceans and will have to depend on algae for our Omega-3 supplies.

      ‘Ingest it its pure form in high concentrations,’ you say. Agree but not entirely possible. You can eat algae or eat algae extract supplement with very low Omega-3 content. If you want high concentrations, you will have to process that Omega-3 into ethyl ester forms. That’s just fine by me. We will all be doing this soon enough. The technology already exists.

  12. Hi VIN,

    Since triglycerides or TG forms of fatty acids are naturally occurring in humans and Fish Oil in TG form is readily recognized by the body and is therefore broken down and absorbed in the small intestines by pancreatic lipases while Ethyl Ester forms of fish oil are initially broken down by the liver and then later on, converted into TG form to be absorbed doesnt this puts the body under less stress? Wouldnt this mean a lot for those who are already challenged and would like to improve their current state of health by taking the Fatty Acid?

    Further more yes, getting the same amount of EPA and DHA in your bloodstream will give your the same benefits, whether your initial sources are from either EE or TG form. However, with a TG form of fish oil, doesnt your body go through less stress in processing the fatty acid and gets to absorb it quickly which would subsequently affect plasma levels quicker?

    • Hi Jojo – you may want to read my TG vs EE revisited here:

      There is a lot of hot air being blown around on the internet about this. Virtually all of it by TG fish oil marketers. The truth is that TG is slightly better absorbed in the short term. I’ll be the first to admit it. The body is still perfectly able to utilize EE fish oils. Arguments made against ethyl ester fish oil are always by people who do not grasp the concept of pharmacodynamics versus pharmacokinetics. There is a difference.

      There is no known stress associated with metabolizing ethyl esters. You do it every time you eat a fruit! The flavors and aroma you smell when you peel an orange are mostly made by esters. Your body certainly is not stressed when you eat fruit and it won’t be stressed by a gram or so of ethyl ester fish oils.

      I go into more detail about these issues in part 2 of this blog and also in the link above.

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