Historically, wasabi may have helped mitigate parasites in sushi, and mercury toxicity has been documented from excessive fish consumption.

“Traditionally, maybe that helped mitigate some of these parasites, but there are documented cases of hatterism. Remember the Mad Hatter from Alice in Wonderland? So, hat makers traditionally used mercury to cure their hats, and they would get mercury toxicity from the hats leeching into their skin, the mercury. Hatterism is mercury toxicity. There are documented cases in the medical literature of hatterism from eating too much fish and sushi.”