Why most fish oil supplements don't work

March 12, 2018

We all know the benefits of Omega 3. That's why over 18.8 million people take fish oil in America alone. Fish oil supplements, however, aren't what they used to be. Manufacturers have gotten creative in their ways of cutting down on their costs, and it's come at the expense of consumers who may not even be aware that the fish oil they are taking is a waste of time and effort. Not all hope is lost, though - If you want the benefits omega 3 has to offer, then here's what you'll need to look out for.

Rancid fish oil

When we buy a fish oil supplement, we expect to be doing our body a favour. Buy a rancid (or oxidised) fish oil supplement however, and you’ll actually be doing more harm than good.

A study done in Spain tested the efficacy of rancid (oxidised) fish oil by splitting women into three groups. Using peroxide levels as an indicator for oxidation, they gave the first group high quality omega 3 capsules, the second group highly oxidised omega 3 capsules, and the third group no capsules. After 30 days the study found that those given the high quality omega 3 capsules had reduced blood triglyceride levels and lower cholesterol levels. The group that received the highly oxidised omega 3 capsules however, actually had worse cholesterol levels than when they started the trial1.

Good thing brands don’t sell us rancid fish oil then, right? Nope – a study done in New Zealand found that 83% of products exceeded recommended industry peroxide levels (a by-product when fish oil becomes rancid), with similar findings replicated by other studies done in South Africa & Norway2,3.

How can you avoid rancid fish oil supplements?

The number one tell-tale sign of rancid fish oil is a fishy taste or smell. Pure fish oil doesn’t taste fishy. If you take your fish oil in a capsule and receive a ‘fishy burp’, then your capsules are rancid and you should throw them away. In order to make sure the fish oil supplements you’re taking are what’s advertised, we recommend taking a liquid supplement – that way you will always know whether the fish oil has gone rancid (it'll taste fishy).

Ethyl ester VS. Triglyceride

There are two forms of omega 3: triglyceride omega 3 and ethyl ester omega 3.

Triglyceride omega 3 is made up of three omega 3 molecules attached to a glycerol backbone. This is the type of omega 3 that occurs naturally in plants & animals, and is the type found in fish oil.

Ethyl ester omega 3 is made up of one omega 3 molecule attached to one ethanol molecule. This type of omega 3 is synthetic and made in a lab.

Although studies suggest that omega 3 absorption is much lower in ethyl ester form, manufacturers continue to use it in their products because it is cheaper4.

How can you make sure the omega 3 is of the triglyceride form?

Manufacturers in North America currently do not have to specify whether they are using ethyl ester omega 3 in their products.

The vast majority of soft gel omega 3 is of the ethyl ester form. The majority of liquid fish oil products however, are in triglyceride form. Why is this? Well, omega 3 in the ethyl ester form oxidises quicker than omega 3 in the triglyceride form, making it taste fishy and less palatable for consumers.

One way to test for the ethyl ester form is using a polystyrene cup. Ethyl ester omega 3 will reveal it self by breaking down a polystyrene cup, causing it to leak through after 2-3 minutes. On the other hand, triglyceride omega 3 will take a couple of hours before it starts to leak through a polystyrene cup.

EPA DHA levels, pharmaceutical grade

In order to get the desired effects from fish oil, you need to make sure that what you’re taking has enough EPA DHA. Fish oil isn’t omega 3: it only contains it. A lot of fish oil supplements will advertise high levels of Fish oil, even if it has low levels of the actual omega 3. For example, a capsule may contain 1000mg of fish oil, but only 100mg of omega 3. You’ll need at least 250mg of the omega 3 daily if you want to start seeing the benefits that omega 3 has to offer. A quick check of the product label should provide you with an answer, but if you want to make sure that products have the levels of omega 3 they’re advertising, look for a certificate of analysis. If they don’t have one on their website then request one - most companies should do them in house or have them done by a third party. Certificates of analysis are a great way to not only ensure you’re getting what’s advertised but also to make sure that the fish oil is pharmaceutical grade i.e. doesn’t contain mercury or other contaminants.




  1. https://www.ncbi.nlm.nih.gov/pubmed/23863036


  1. https://www.nature.com/articles/srep07928


  1. https://www.ncbi.nlm.nih.gov/pubmed/24240381


  1. https://www.ncbi.nlm.nih.gov/pubmed/20638827



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