Complete Guide to Mercury in Fish Oils: What You Need to Know

fish oil mercury

Is there mercury in fish oils? How do you know the fish oil you’re taking is really free of mercury, PCB’s, lead and other contaminants? Is it better to eat fish or take fish oil supplements?

While fish oils provide an excellent source of omega 3 fatty acids, there’s a possibility you could be putting toxic chemicals in your body.

Here you’ll learn everything about where mercury comes from and how it can get into your fish oil.

You’ll also learn a simple, fool-proof method to help you check the purity of your fish oil to see if it’s been properly tested for mercury and other contaminants.


The Benefits of Fish and Omega 3 Fatty Acids

We all know how fish is good for us and we should try to eat 2 – 3 servings of fish per week. Fish is a rich source of omega 3 fatty acids and these special fats play a direct role in preventing cardiovascular disease.

These healthy fatty acids have been proven to reduce inflammation, lower your risk for heart disease and improve mood.

However, your body can’t manufacture them, so you need to get them through your diet from eating fish or taking omega 3 supplements.



There’s Something Fishy Going On Here….

However, the problem with eating fish is it may contain high levels of mercury, called methylmercury.

Methylmercury is toxic and is absorbed into the fish from the water they swim in. Fish can also consume mercury from eating other fish.

mercury in fish oilsScientists have found that large fish higher up in the food chain (shark and swordfish) have higher tissue concentrations of mercury (up to 1 µg per gram of fish weight) and smaller fish (such as tuna, trout, pike and bass) have lower levels of 0.1 – 0.5 µg/gram.

And scientists have proven that there’s a direct correlation between how much fish you eat and your relative mercury levels in your body, as well as exposure to other contaminants such as lead and Polychlorinated Biphenyls (PCB).

Studies found that excessive mercury levels may promote atherosclerosis and free radical damage.

The symptoms of mercury poisoning include itching, burning, skin discoloration, kidney dysfunction, loss of memory and profuse sweating.

Due to the risks of mercury exposure to an unborn baby’s brain and nervous system, doctors have advised pregnant women to limit their intake of fish.



So Where does all this Mercury Come From?

So mercury is a natural element in our world and we’re normally exposed to very low levels of mercury on a day-to-day basis.

mercury droplets

mercury droplets

This silver colored substance is found in small amounts in many rocks and natural background levels of mercury can be found in the air, soil and water.

Dentists used to use mercury in dental fillings, but this practice is declining due to a decrease in tooth decay and the appearance of better substitute materials.

Did you know that you can also get mercury from nasal sprays and eye drops?

I was surprised to learn this after reading the FDA database of mercury levels in drugs and other biologic products.

Other sources of mercury are thermostats, thermometers and fluorescent lamps.

Although there are natural sources of mercury, extraneous forms of mercury are released into the environment from burning coal for fuel, waste incineration and smelting mines.

Air pollution is source of mercury

And dozens of factories throughout the world could be unwittingly releasing excessive mercury into the environment, indirectly increasing mercury levels in fish and other wildlife.

Obviously, this raises the concern that eating fish that may increase our intake of mercury. There’s no doubt that eating fish offers us many health benefits; the omega 3 fatty acids are proven to improve cardiovascular health along with many other benefits.

The normal mercury levels in people that don’t eat fish are about 2.0 micrograms per Liter (mcg/L) and in people that eat 2 – 4 servings of fish per week may have mercury levels up to 8.4 mcg/L.

So how do we get the health benefits of fish but avoid unnecessary exposure to mercury?



Scientists finds Safe Amounts of Mercury in Fish Oils

Researchers believe that using a concentrated fish oil supplement may be the key to getting the healthy fats from fish while also avoiding exposure to excessive levels of mercury.

The big question is there actual exposure from mercury in fish oils and how much is a safe level?

It just so happens that some doctors at Harvard Medical School asked the same question.

They recently tested the amount of mercury in 5 different brands of fish oil bought from health food stores and the internet.

Samples of Fish Oils Tested for Mercury:

All of the above 5 sample fish oil capsules were punctured and the liquid contents were sent for mercury level analysis. Mercury levels lower than 6 ug/L. would be labeled as insignificant levels.

Results showed none of the 5 brands contained significant amounts of mercury.

Nordic Naturals Ultimate Omega, Sundown, and Kirkland brands all showed zero levels of mercury (below 6 mcg/L).

The Omega Brite brand had 12 mcg/L of mercury and the CVS brand contained 10 mcg/L.

Researchers concluded:

  • The mercury in fish oils analyzed is similar to mercury levels found in people who regularly eat fish.
  • All 5 samples of fish oil supplements had negligible amounts of mercury. Researchers believe this means the mercury is removed during manufacturing process or the fish sources used in these samples are relatively free of mercury.

The study also shows that even large doses of concentrated fish oils should not cause mercury toxicity.

For example, researchers found that six 1000 mg. Omega Brite fish oil capsules contains 0.072 mcg of mercury.

This is equivalent to 2.1% of the mean daily mercury intake in the typical North American population.



How to Determine the Purity of your Fish Oil:

An easy way to check the mercury content, purity and quality levels of fish oils is the International Fish Oil Standards (IFOS).

The IFOS is an independent lab that routinely tests a variety of fish oil supplements following very strict standards set forth by the World Health Organization (WHO) and the Council of Responsible Nutrition.

fish-oil-softgels-smallerThe majority of the fish oils tested are submitted by companies that wish to have their oils tested. The fish oil companies pay a fee for this service and the test results are published on the IFOS website for you to see.

However, you should know that not all fish oils are tested for the same number of parameters.

There are some companies that will meet the minimum standards and other fish oil companies may strive for extremely strict controls.

Avoiding mercury in fish oils is quite simple when you have the information you need to make an informed decision.

It’s recommended you research the company behind the product you’re interested in buying. Doing your due diligence will help you find a high quality product to help you avoid any traces of mercury in fish oils.


Research References:

Mercury in fish oils, and the risk of myocardial infarction. New England Journal of Medicine 2002;347:1747–1754. Guallar E, Sanz-Gallardo MI, van’t Veer P. et al.

Blood mercury levels in US children and women of childbearing age 1999–2000. JAMA 2003;289:1667–1674. Schober SE, Sinks TH, Jones RL. et al.

Measurement of Mercury Levels in Concentrated Over-the-Counter Fish Oil Preparations: Is Fish Oil Healthier Than Fish? Archives of Pathology and Laboratory Medicine: Vol. 127, No. 12. S. Foran, J. Flood, K. Lewandrowski

Mercury and fish oil supplements. MedGenMed 2001;3:20 Schaller JL

Intake of mercury from fish, lipid peroxidation, and the risk of myocardial infarction and coronary, cardiovascular, and any death in eastern Finnish men. Circulation 1995;91:645–655. Salonen JT, Seppanen K, Nyyssonen K. et al.


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