Warning on False or True Morels and Button Mushrooms with Potential Toxicity Linked to Hydrazinic Toxins: An Update

Recently, consumption of the gyromitrin-containing neurotoxic mushroomGyromitrasp. (false morel), as gourmet food was hypothesized to play a role in sporadic amyotrophic lateral sclerosis genesis. The present review analyses recent data on edibility and toxicity of false and true morels andAgaricusspp. Controversy about the toxic status ofGyromitra esculentawas due to variable toxin susceptibility within consumers. We suggest thatVerpa bohemica, another false morel, is also inedible. We found a temporary neurological syndrome (NS) with cerebellar signs associated with high consumption of fresh or dried true morelsMorchellasp. After ingestion of crude or poorly cooked fresh or dried morels, a gastrointestinal haemolytic syndrome was also observed. Agaritine, a water soluble hydrazinic toxin closely related to gyromitrin is present along with metabolites including diazonium ions and free radicals, inAgaricusspp. andA. bisporus,the button mushroom, and in mice after ingestion. It is a potential weak carcinogen in mice, but although no data are available for humans, a lifetime low cumulative extra cancer risk in humans can be estimated to be about 10(-5). To conclude, a safety measure is to avoid consuming any true morels or button mushrooms when crude or poorly cooked, fresh or dried.