Fish with Mercury Are Safe – and Healthy – to Eat

By Lura Jackson


As a coastal community, eating fish is synonymous with life in Downeast Maine. That lifestyle has been challenged in recent decades by a widely publicized report from federal agencies that cautions consumers to avoid fish that are high in mercury content to avoid mercury poisoning. Scientific understanding, however, has repeatedly demonstrated that ocean-based fish and other seafood have a natural ability to counteract mercury. Not only does this make some fish safe to eat it, also grants them the ability to cleanse the system of heavy toxins. 

Mercury is a potent neurotoxin that can cause neurological disorders and kidney malfunction, and it can even lead to death. As such, the vociferous concerns related to consuming too much of it are understandable. Concerns escalated publicly in 2004 when the EPA published guidelines for mothers and expecting mothers to limit their mercury intake to avoid damaging their unborn children. These recommendations neglected findings going back as early as 1967 that recognize that the much more important variable in whether or not fish is safe to eat is selenium. The University of North Dakota released an extensive study in 2009 to clearly demonstrate the relationship between mercury and selenium, thereby refuting the EPA’s claim.

Selenium actively works to remove mercury from the body, and studies have now demonstrated that eating fish that has a “high” level of mercury – but a “higher” level of selenium – will actually cause mercury levels in the body to decrease. As such, not eating seafood that is rich in selenium can cause problems related to passive mercury buildup from the environment. According to the University of Wisconsin, the largest source of mercury by far is emissions related to fossil fuel burning power plants, particularly coal. These emissions fall into fresh water sources and into the soil, contaminating drinking water and grown foods.

How harmful is it to not consume seafood that has both selenium and mercury? In a recent UK study involving 14,000 mothers and children, it was found that consuming less than 12 ounces of fish per weak caused “significant impairments of communication skills and verbal IQ at six and eighteen months of age”, analyst Chris Kresser reports. The worst-affected children were born to mothers who consumed no seafood during the trial. The study clearly indicates the role of seafood in removing harmful mercurial toxins. Not consuming enough selenium in general has been tied to increased rates of cancer, heart disease, and fatigue in adults. 

Consuming selenium-rich seafood is one of the best ways to cleanse mercury from the system, but it is important to know which seafood fits the bill. Luckily, most seafood has a much larger amount of selenium than mercury, although fans of mako shark will have to curtail their habit. The fish that has been rated as having the highest selenium to mercury ratio are yellowfin tuna, albacore tuna, skipjack tuna, mahi mahi, and wahoo (no word yet on where local buyers can find some wahoo, although an update will be provided if and when a source turns up). Also ranking notably well are flounder and salmon. Aside from mako shark, pilot whales, and most sharks, which have a higher mercury to selenium ratio, consumers are advised to avoid swordfish and grouper, both of which have a 50-50 ratio. All other ocean-going fish are generally safe and healthy to consume.