Mercury and Fish

          In recent years, the consumption of fish has been widely advocated due to the health benefits associated with omega-3 fatty acids (FAs).  Diets high in fish, however, have also been associated with elevated exposures to toxic chemicals, mainly methyl mercury, and have therefore been linked to adverse health effects.  Such mixed messages have led to much confusion regarding whether or not, or to what extent, fish should be included in one’s diet.  Consequently, many organizations and agencies have published warnings about which fish should be avoided due to high mercury levels.  These messages, however, are limited in that they describe only fish that are bad because of high mercury without describing those that are most healthy due to high levels of FAs.  In this article, I’ve not only listed certain popular seafood to be avoided due to high levels of mercury, but also included fish that are important to good health due to high FA levels.
          For those unfamiliar with the health effects of methyl mercury, this compound is a widely know neurotoxin.  While toxic to adults, it is especially toxic to the developing fetus and therefore should be particularly avoided by pregnant women.  Lower IQ in children whose mothers consumed high-mercury fish while pregnant has in fact been observed in major studies.  Methyl mercury is also linked to heart disease and therefore increased heart attacks.  To the contrary, omega FAs have been shown to improve brain function and reduce heart disease.  This is why it’s important not simply to eat fish low in mercury, but to eat those high in FAs, otherwise you’re missing out on the benefits of fish consumption!  Note that if you don’t like fish, you can still obtain beneficial omega-3 FAs by taking dietary supplements..

High-Mercury (To Avoid):

  • Shark
  • Swordfish
  • Marlin
  • Tuna (yellowfin, ahi, canned albacore)
  • Mackerel (king, Spanish, Gulf)
  • Tilefish
  • Marlin
  • Sea bass (Chilean)
  • Orange roughy
  • Grouper
Low to Moderate Mercury + High-omega FAs (To Eat):

  • Salmon (Atlantic)
  • Herring
  • Trout
  • Flounder
  • Pollack
Other seafood such as tilapia, cod, halibut, lobster, and certain sea bass are okay to eat given their low mercury content, however, since they are not high in FAs, they are not the BEST choices.

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                                                                                                       -Shahir Masri


  1. Very informative! I've always eaten tilopia because it has low mercury and is sustainably fished, which is EXTREMELY important to consider from an environmental perspective. I didn't know it was low on healthy nutrients like omega FAs. So, maybe we need a list of fish that are 1)sustainably fished, 2) low on mercury and other toxics compounds and 3) high on health omega FAs. So we need to know, how sustainable are the five fish you listed on the bottom????
    Thanks for all your great info!!! :)

  2. Fish has been known to have a lot of beneficial benefits to improve our health. However, it also saddens me that because of that known fact, there are fishermen who use inhumane methods to collect and gather a mass amount of fish or just over fishing. Over fishing has caused many native species to go extinct and many current species to become endangered. Once something like that has happened, it is hard to recover something like that to its original environment.

  3. So is it that pregnant women should avoid eating fish at all costs? Or just the fishes with high mercury levels? This article and in today's presentation reminded me of the movie "The Cove", where people were able to actually film how Japan catches dolphins in this secluded area.

  4. How interesting! And what a coincidence because on my way home from school today I actually heard something about this on the radio. It was talking about how albacore tuna has high levels of mercury. Reading articles like this is slightly frightening to me because it makes me wonder what ELSE is in all of the other foods that I eat.

  5. I was wondering, because shark is on the high mercury side, does that mean that stuff like shark fin soup would be harmful to consume, even though in many cultures, it is like delicacy. Also i was wondering about catfish, because my family tend to eat catfish a lot, is that high in FA, high in mercury, or neither.

  6. It was interesting to me because I never knew that adult females with fetuses within them can be affected by eating high mercury fishes. I've also been thinking, if the fishes contain mercury does that mean that the females should avoid eating fish while being pregnant?

  7. I saw a movie called "the Cove" and it too talked about this issue and how people who consume fish or mammals in the ocean, in that case dolphins consumed by the Japanese, will get mercury poisoning which would not only affect the people consuming the meat but if a woman were to be pregnant and ate that contaminated meat her fetus would also be affected and her baby would come out with serious birth defects.