Tuna: Tasty or Toxic?

Tuna: Tasty or Toxic?

By Emi Yasuda


Since the advent of canned tuna over 100 years ago, this nimble fish has swum from the status of mystery meat to lunchtime essential. With 22 grams of protein, omega-3 fatty acids, and a wealth of Vitamin B, tuna would seem like the perfect choice for a healthy meal. But as pollution increases, so are fears of fish’s mercury content.

A heavy metal, mercury serves no purpose in the human body. Unlike iron and zinc, its only potential effects are adverse. When you ingest mercury it gets absorbed by the small intestine, shipped to the liver, and then is incorporated into bile or blood. During mercury’s time in your body, it can become stored in tissues as long as 90 days, and also disguise itself as an amino acid by binding to cysteine, allowing it to bypass your brain’s natural barriers.

Eating tuna, however, is unlikely to drive you mad. In adults who frequently consume fish, symptoms of mercury toxicity such as tremors, neurologic symptoms, and sensory problems are rarely reported. It turns out that tuna’s high protein and selenium content counteract adverse effects. Thus, while mercury may lessen health benefits, for the average person, consuming fish is not harmful overall. As indicted by peer-reviewed reports from the Journal of the American Medical Association, and the Institute of Medicine, there is no consistent evidence that fish-related mercury exposure causes any significant health effects on the average adult. However, in pregnant women and young children, fish consumption is best limited to avoid inhibition of nervous system development.

More often than not, fish is a great health choice! Despite the slim potential for mercury poisoning, eating fish will not cause “Brain Rot!” as suggested on the PETA website, and the majority of symptoms are only temporary. The omega-3 fatty acids in fish have well-established health benefits. Anti-inflammatory, and cardiovascular properties such as reduced risk of blood clots and reduced blood pressure have been supported by multiple studies. Fish consumption can lower risk of stroke, obesity, asthma, and even cancer according to Dariush Mozaffarian, DrPH, dean of the Tufts University’s Nutritional Science Department. Fish intake also reduces your risk of a heart attack by about a third. Perhaps it’s a good thing that the U.S. ate approximately one billion pounds of tuna last year alone!

Whilst the health benefits of fish are astounding, it is still good to be conscious of how much mercury you are taking in. The EPA safety level for fish is 0.1 mcg of mercury per kg of body weight per day. But keep in mind that even if you exceed this limit, it is ten times lower than the level at which the EPA states a risk occurs in young children. The bottom line is that the evidence is inconclusive whether or not fish-related mercury exposure has any long-term effects in adults at average levels of consumption, and that even if there are, these are only lessen fish’s overall benefit.

Want to find out the best levels of fish consumption for you? Visit the Environmental Working Group’s website to plug in your info and receive custom recommendations. http://www.ewg.org/research/ewgs-good-seafood-guide


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