Do You Know What’s in Your Fish Oil Supplement?

Millions of Americans and Canadians take fish oil supplements on a daily basis, in hopes of maintaining good cardiovascular health. In 2013 these supplements generated $1.2 billion in sales in the U.S., which goes to show that it’s in high demand. Fish oil supplements contain omega-3s, which are wonderfully healthy fatty acids that are beneficial for brain and nervous system health, protective against heart disease, have anti-inflammatory qualities, and may reduce the risk of Alzheimer’s and other chronic diseases. It all sounds great, except that many of these supplements might not contain exactly what their labels claim.

LabDoor is a testing company that examined the 30 top-selling brands of fish oil supplements in the U.S. Researchers assessed the supplements’ omega-3 content, their mercury levels, and whether the supplements showed signs of rancidity.

First, they found that 6 out of the 30 supplement brands contained omega-3 levels that were, on average, 30 percent lower than stated on the labels. Then they examined two specific omega-3s – docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Twelve of the 30 brands had DHA levels that were an average of 14 percent lower than stated on the labels. Current research has also shown that DHA intake should be higher than EPA, but the supplements trended in the opposite direction, generally serving up twice as much EPA as DHA.

Next, researchers assessed the presence of mercury in the supplements, and found that all brands tested low. They ranged from 1 to 6 parts per billion per serving, which is well within the upper safety limit of 100 parts per billions, a number that’s set by the Global Organization for EPA and DHA Omega-3s (industry trade group).

Finally, they looked at the level of deterioration within the supplements, which is measured by the degree of oxidization, occurring in two phases. Primary and secondary oxidization are measured to form a TOTOX (total oxidization) score, in which the upper safety limit is 26. All brands showed levels of oxidization above 20, averaging a TOTOX score of 21.3.

LabDoor ranked all 30 brands in order of quality and value, which you can see on their website here.

So what does this mean for fish oil supplements? Dr. Philip Gregory, editor-in-chief of the Natural Medicines Comprehensive Database, says in this New York Times article that it’s not clear whether fish oil can help:

“It may be that for people with heart disease who are already well treated with statins or high blood pressure medication, fish oil supplements may not offer any additional benefit. Similarly, for those who already consume fish in their diet, adding a supplement probably doesn’t offer additional benefit.”

Whether fish oil supplements can help those people who don’t eat fish regularly wasn’t stated in the study’s conclusion, though Dr. Gregory suggests making sure the supplement you buy has a USP Dietary Supplement Verification Stamp. Brands can submit their supplement to this non-profit group for stringent assessment of quality, purity, and potency. You might be better off just eating fresh, fatty fish twice a week, such as sardines or wild salmon.

Photo Credit: CC BY 2.0 yesudeep

Does Fish Oil Really Boost Prostrate Cancer?
How Many Omega-3s & 6s Are Healthy?
Are You Vitamin B12 Deficient? (And Does it Matter?)

article by Katherine Martinko


Elena T.
Elena Poensgen5 years ago

Thank you :)

Tanya Selth
Tanya Selth5 years ago

Im not much of a fish eatter and have found that fish oil supplements certainly help me when Im getting joint paint (ostero-arthritis).

I dont find them a quick fix thing thou eg I find I need to take them for weeks or 2-3mths before I really do notice quite a benefit and become pain free again.

I suggest they are worth a try for some problems as many find they can help.

Carole R.
Carole R5 years ago

I always wonder about these. I used to take them regularly, as suggested by my Dr. Then I read some of the studies and cut back. I still take them a few times a week but really wonder if they do any good or am I just making some people rich. Guess I'll keep wondering until something conclusive comes out. ;0/

Fi T.
Past Member 5 years ago

Check before use

Fred h
Fred Hoekstra5 years ago

Thank you Kara, for Sharing this!

I sure do!

Shanti S.
S S5 years ago

Thank you.

Lindsay Kemp
Lindsay Kemp5 years ago

Oh dear!

Sue Matheson
Sue Matheson5 years ago


JL A5 years ago

sounds like they replicated the results got a decade ago

Les Allerton
Past Member 5 years ago

The omega 3 that we benifit from is found in green vegetables including seaweed, it is consumed by small creatures and small fish and works its way along the food chain to the larger fish that we eat, Fish store the oil as omega 3 exactly as they find it. Now other animals that we eat consume lots of vegatable matter mainly grass rich in omega 3 but unlike fish they do not store the oil but convert it to another type of fat not so healthy for us. This is also an indication why farmed fish is not a good product to eat, farmed fish are fed on animal bi products so they store the wrong type of fat.