Canada has the strictest health supplement standards in the world, so their requirements for fish oil products are very stringent. In fact, the vast majority of fish oil supplements in the US are prohibited in Canada! Canada isn't the only one, as Sweden and Denmark have also banned these omega-3, and the UK and Norway will soon follow suit. Why? The answer has to do with how bioavailable the omega 3 fatty acids are, or how easily your body absorbs them and makes use of them. The explanation may be more scientific than you care for, but I will make it easy to understand.
The reason fish oil pills are so beneficial for your health is because they contain omega-3 fats. Omega-3s are fats that actually good for the body -- in fact, they're a key part of optimal health. Naturally, Omega-3 fatty acids that exist in fish are in the form of triglycerides. This means every molecule has 3 omega-3 fatty acids bound to an alcohol base, glycerol. These certainly are not the type of triglycerides that your physician looks at your blood work for, so don't worry.
All fish oils must be purified due to the harsh reality of high levels of toxic contamination in the oceans, and thus fish. Many fish oil producers use a molecular distillation process to achieve high levels of purity. However, the omega-3s that originally came as triglycerides then become converted into a new molecule, called an ethyl ester (or EE). Another alcohol base, ethanol, replaces the glycerol alcohol base in triglycerides.
What's the problem? Alcohol bases are all the same, right? Actually, no, there is a huge difference that has prompted many countries to make it illegal! It turns out that the more natural TG-based fish oils are absorbed by the body *far* more easily than the unnatural EE-based version. In fact, clinical studies have shown that TG has a 300% greater absorption rate, meaning its EE counterpart is only about 1/3 as effective as TG! But that's certainly not where the limitations stop. Ethyl ester (EE) omega-3 fish oil is absorbed and used by the body at a markedly slower rate - sometimes up to 50x more slowly than TG! For the reasons mentioned, this Ethyl Ester fish oil is illegal in Canada and other countries. However, it is completely legal to sell EE in the US.
It appears to be a catch-22. If we aim to avoid consuming toxic contamination, it seems inevitable that we must take a fish oil supplement that the body can barely make use of, right? Think twice! EE can definitely be converted back into TG, which is how purified oils are available in Canada. But this certainly begs the question: If triglyceride-based omega-3 is superior to EE-based, why don't fish oil manufacturers in the US create TG omega-3 fish oils? Higher costs, of course! It costs about 30% more to convert EE back into TG, and since most US consumers don't know the difference, most US manufacturers don't bother to pay the additional fees.
Furthermore, very few of them actually reveal that their fish oils are ethyl esters, so it's extremely hard to tell what they contain. Because most fish oil supplements are EE in the United States, you can safely assume that a supplement is EE unless the product indications that it's a TG. There are two fish oil brands available for purchase in the US that I can recommend because they're both TG-based and certified by the International Fish Oil Standards program; they are Nordic Naturals and See Yourself Well.
Trigylceride-based omega-3s are far superior to the majority of omega-3 products being sold, according to some pretty convincing research. If you want to be sure that you're taking the best omega-3 product for your health, make sure yours is a TG-based oil.