Mercury is a metal that has no place in our diet. Yet it is present in all types of seafood. The mercury originates from natural phenomena like volcanoes, but more importantly from industrial processes and mining. Rain takes it out of the atmosphere and into the sea, where it enters our food chain through fish.
Accordingly, various health authorities recommend that although fish is excellent in the diet in some respects, its consumption should be limited because of the threat of mercury. Once in your body, it takes months and maybe years for your system to get rid of it.
The effects of mercury are not fully known, but it has been linked to Alzheimer’s, and Parkinson’s diseases. In consequence, Dr. Bredesen, in “The End of Alzheimer’s” recommends you avoid Tuna altogether. And Doctor Greger, in “How not to Die” recommends you consume no fish or fish oils at all.
If you do want to eat fish, then those containing low levels of mercury are generally short-lived, and include: Salmon, Shrimp, Pollock, Cod, Sardines, Atlantic mackerel.
Fish with higher levels include haddock, and Skipjack tuna.
Fish with the highest levels are generally long-lived and higher up the food chain, and include: Albacore tuna, Yellowfin Tuna, Swordfish, Halibut, Shark.
The National Health Service in the UK advises pregnant women to eat no more than two portions of oily fish a week, and that children under the age of 16 should avoid eating any shark, swordfish or marlin, because the levels of mercury can affect their nervous system.
In my opinion, if mercury is that bad for pregnant women and children, then who knows what the risks might be for older people? Is it just that there haven’t been enough studies yet?
In the USA, the Environmental Protection Agency gives similar advice. “To enjoy the benefits of eating fish while minimizing exposure to mercury, you should: Eat mainly types of fish low in mercury, and Limit your consumption of types of fish with typically higher levels of mercury.”
On the plus side for fish, it is full of nutrients, so there’s an argument not to give up on fish altogether. Having no fish could be worse for your health than having too much, if you don’t get similar nutrition by other means!
We must also mention the mercury in dental fillings. Generally, it’s benign, that once in place it stays there. But there have been examples where the mercury has ‘leaked’ out into the body, and accordingly some people have had fillings replaced with non-mercury alternatives to avoid any possible risk.
If you are in any doubt about your level of mercury, it’s possible to have this tested (at a cost). The test can tell you how much mercury you have in your body, and whether it’s from food or from your fillings, and that can guide you as to actions you might want to take.
What do I personally do about Mercury?
I stopped eating tuna near the end of 2018, but from January 2019 I’ve eaten almost no fish, in line with Doctor Greger’s advice. Maybe a few prawns, that’s all! To make sure I get my long-chain Omega 3, I take a daily capsule of Algae oil. This is an essential in the diet, and algae oil is the only practical source for vegans.