Mercury In Tuna No Health Risk, New Study Shows

More Research Disproves Negative Assumptions


Eating tuna is beneficial for health and can improve maternal and fetal development, according to a new research paper authored by scientists, who have been studying the topic of mercury in seafood for over a decade. One of their key messages is that when looking at mercury content, selenium should also always be addressed to fully understand their relationship and potential impact.

Dr. Nicholas Ralston and Dr. Laura Raymond have compiled research progress from over 50 years, regarding mercury and selenium content in seafood, and the relationship between the two, in their new paper now published in the BBA Journal.

They conclude that any fish containing more mercury than selenium should not be consumed by children or pregnant women, mentioning certain varieties of shark, large specimens of swordfish and halibut.

However “nearly all other seafood and ocean or freshwater fish provide far more” selenium than mercury to consumers, it is stressed, with tuna therefore falling into this category.

Such fish will actually improve, rather than diminish maternal and fetal selenium status, “while providing nutritional benefits for health and development” it is said. An improved selenium status is positive due to the fact that selenium-dependent enzymes are vitally important for brain tissues.

Previously the scientists have presented at the European Tuna Conference in Brussels, stressing to the tuna industry that the high levels of selenium present in tuna, which commonly strongly surpass mercury content, means that tuna consumption does not cause mercury toxicity and can actually help offset potential mercury intake from other foods.

It was shown in their presentation that albacore, bigeye, yellowfin and skipjack tuna all contained selenium levels that far surpassed their minor mercury content, and this ratio can actually help keep the brain protected.

For years however the tuna industry has been hit with claims that mercury levels in the fish are harmful to brain development, but this paper now joins other research that disproves this assumption.

Ralston and Raymond have previously taken their findings to the European Commission DG SANTE to push for changes in the way health authorities check mercury levels in seafood. Currently just one single toxicity – like mercury – is tested alone, irrespective of selenium levels, however the scientists advocate for the ratio of each to be taken into account. While the DG SANTE has said it will look at potential changes, there has been no reported move taken yet.

The full study ‘Mercury’s neurotoxicity is characterized by its disruption of selenium biochemistry’ is available in the journal BBA – General Subjects.