Mercury – what is safe?

Fish and seafood are excellent sources of essential fatty acids (EPA/DHA) protein, calcium, and iodine. As Naturopaths, it is common to have fish included in a dietary prescription for our clients, often 2-3 times a week. However, fish appear to be the primary source of mercury toxicity in humans, as mercury works its way up the food chain from small organism to larger fish, bioaccumulating in larger amounts here.

It has been shown to induce oxidative stress, mitochondrial dysfunction, contribute to cardiomyopathy, IBD, indigestion, ulcers, dysbiosis and reduces endocrine function by disrupting pituitary, thyroid and adrenal glands, pancreas and the female hormonal profile¹. As for pregnant women, it can affect the development of the nervous system of an unborn baby¹. This is enough to out-weigh the nutritional benefits listed above. However, there are some types of fish that can be consumed and tend to have the lowest mercury concentration².

- Sardines

- Anchovies

- Butterfish

- Atlantic salmon (not farmed/wild)

- Snapper

- Trout (freshwater)

- Squid

- Mackerel

- Ocean perch

- Trevally

Fish high in mercury²:

- Barramundi

- Ling

- Wild salmon

- Shark

- Swordfish

- Ray

- Bluefish

Canned tuna has seen mixed results for mercury testing. Low to high concentrations have been identified in fresh and canned tuna around the world and therefore mixed recommendations have been revealed. For that sake, aim to only consumer 2-3 cans per week of good quality sustainable canned tuna³.

1. Rice, K.M., Walker Jr, E.M., Wu, M., Gillette, C. and Blough, E.R., 2014. Environmental mercury and its toxic effects. Journal of preventive medicine and public health, 47(2), p.74

2. Better Health Channel 2013, Mercury in fish. State of Victoria, accessed: 29th September, Received from:

3. Kumar, G., 2018. Mercury Concentrations in Fresh and Canned Tuna: A Review. Reviews in Fisheries Science & Aquaculture, 26(1), pp.111-120.

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