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

Written by Katherine Martinko

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.

This post was originally published in TreeHugger

Photo Credit: yesudeep


Carrie-Anne Brown

thanks for sharing :)

Karen Garnett
karen Garnett3 years ago

This article lacked specifics which would have helped me. Like brands. I do take a fish oil supplement and will continue to do so.

Jacob Ross
Jacob Ross3 years ago

Ooh - well - we better stop taking fish oil supplements and sacrifice the 70% of Omega 3's that they DO contain, right?

I swear - I'm almost convinced that Care2 is subsidized by drug companies......

"It may be that for people with heart disease who are already well treated with statins or high blood pressure medication".....

Already "well treated"???? Have you looked at the side effects of these toxic chemicals? Can you honestly suggest that it's better to use that crap than to take Omega 3's and other supplements that will not damage your liver and other vital organs..... and/or give you a "potentially life threatening reaction"?

Quit with the anti-supplement BS - it's our choice as to whether to take them or not - and if you do convince some people to stop taking them, and their health deteriorates - it will be your fault!

Julie vanberkel
Julie vanberkel3 years ago

As Phobe D says, hemp oil is just as good, apparently, if not better. Just be aware that it is also ill advised to take if you have certain medical conditions. Do your homework first on this before buying, as it's not cheap.

John chapman
John chapman3 years ago


I eat fish, & I'm not too sure what's in them either.

Carol M.
Carol M3 years ago

If you're looking for omega 3's, go right to the source - algae. Where do you think the fish get it from?

Phoebe Devaughn
Phoebe D3 years ago

A few months ago I read that hemp oil is just as good if not better for your heart than fish oil. Just saying.

Debbie Miller
Debbie Miller3 years ago

Well, I like to take fish oil. I find it disturbing that some of the supplements including fish oil don't have the amounts they claim and in some cases have added ingredients that should not be included... not to mention the oxidative effects that take their toll.

Anne Moran
Anne Moran3 years ago

It's hit n' miss...

There's good and bad in every pill/supplement/vitamin, etc...

Jessica Grieshaber

thankfully i don't take fish oil right now