If you don’t eat a lot of fatty fish, then you may want to consider taking a supplement.
However, there are hundreds of different omega-3 supplements available. Not all of them have the same health benefits.
This detailed guide explains everything you need to know about omega-3 supplements.
Fish oil comes in both natural and processed forms.
The processing can affect the form of the fatty acids. This is important, because some forms are absorbed better than others.
- Fish: In whole fish, omega-3 fatty acids are present as free fatty acids, phospholipids and triglycerides.
- Fish oil: In conventional fish oils, omega-3 fatty acids are mostly present as triglycerides.
- Processed fish oil: When fish oils are processed, either to purify or concentrate them, they become ethyl esters, which are not found in nature.
- Reformed triglycerides: The ethyl esters in processed fish oils can be converted back into triglycerides, which are then termed “reformed” triglycerides.
As a rule of thumb, the absorption of omega-3s in the form of free fatty acids (mostly found in food) is 50% greater than triglycerides, and the absorption of triglycerides is 50% greater than ethyl esters.
This is the oil that comes from the tissue of oily fish, mostly in the form of triglycerides.
It is the closest thing you can get to real fish.
Natural fish oil contains several important nutrients.
Processed fish oil is usually purified and/or concentrated, which transforms the fats into the ethyl ester form.
Purification rids the oil of contaminants, such as mercury and PCBs. Concentrating the oil can also increase EPA and DHA levels. In fact, these oils may contain 50–90% pure EPA and/or DHA.
Processed fish oils make up the vast majority of the fish oil market, as they are cheap and usually come in capsules, which are popular with consumers.
The body does not absorb processed fish oil as well as natural fish oil because it is in the ethyl ester form. However, some manufacturers process the oil even further to convert it back into a synthetic triglyceride form, which is well absorbed (1, 10).
These oils are referred to as reformed (or re-esterified) triglycerides. They are the most expensive fish oil supplements and only make up a small percentage of the market.
Krill oil is highly resistant to oxidation, as it naturally contains a potent antioxidant called astaxanthin (17).
Additionally, krill are very small and have a short lifespan, so they don’t accumulate many contaminants during their lifetime. Therefore, their oil doesn’t need to be purified, and is rarely found in the ethyl ester form.