{"id":4010,"date":"2026-05-15T08:24:49","date_gmt":"2026-05-15T08:24:49","guid":{"rendered":"https:\/\/seleniumfacts.com\/?p=4010"},"modified":"2026-04-17T08:57:02","modified_gmt":"2026-04-17T08:57:02","slug":"selenium-and-mercury-in-the-fish-we-eat","status":"publish","type":"post","link":"https:\/\/seleniumfacts.com\/index.php\/selenium-and-mercury-in-the-fish-we-eat","title":{"rendered":"Selenium and Mercury in the Fish We Eat"},"content":{"rendered":"
What should we know about eating fish and exposure to mercury in fish?<\/h5>\n
\"Fish
Fish and chips. How careful should we be about eating fish? Which fish contain more harmful mercury than protective selenium? What should pregnant women know about eating fish during pregnancy?<\/strong><\/figcaption><\/figure>\n

Fact: Most fish contain mercury. Mercury is a toxic substance. Fortunately, most fish contain both selenium and mercury. On a molar basis, most edible fish contain more selenium than mercury. That makes it safe to eat most fish [Ralston 2024; Ralston 2016].<\/strong><\/p>\n

The selenium in fish binds tightly to mercury. The binding forms stable complexes that prevent mercury from damaging our cells. When there is more selenium than mercury (on a molar basis), this binding effectively neutralizes mercury\u2019s toxicity. As a result, the mercury becomes biologically inactive and far less harmful when we eat the fish [Ralston 2023].<\/strong><\/p>\n

Even so, having just enough selenium available to neutralize the mercury exposure is not good enough. Logically, there must be a surplus of selenium<\/a>. Without a surplus of selenium, there will not be enough selenium to synthesize antioxidant selenoenzymes. And, we need the antioxidant selenoenzymes to counteract the harmful free radicals in the brain. Providing more selenium, via supplementation if necessary, keeps selenoenzymes doing their antioxidant job.<\/p>\n

How Do We Know if We Need Supplementary Selenium?<\/h5>\n

The selenium researcher Nick Ralston has developed a health-benefit value metric to determine whether it is safe to eat certain fish. Basically, Ralston\u2019s metric subtracts moles of mercury in a fish from moles of selenium. Accordingly, if the result is positive, then there is selenium surplus. This corresponds to protective potential. However, if there is a negative result, then there is a higher potential risk [Ralston 2016].<\/p>\n

What Fish are Generally Safe to Eat?<\/h6>\n

Using Ralston\u2019s metric<\/a> shows that the following fish are generally safe to eat:<\/p>\n