Wild Mushroom Suspected in Muscle Loss

 

(AP) -- A wild mushroom popular across both Europe and the United States may dissolve the muscles and prove toxic in people who continually eat it, according to a study in The New England Journal of Medicine.

Twelve people were hospitalized for severe weakness and muscle loss after eating the mushrooms, and three of them died, wrote Dr. Regis Bedry of the poison center of University Hospital Pellegrin in Bordeaux, France.

The only connection among the cases, which occurred from 1992 through 2000, was that all 12 -- seven women and five men -- had eaten at least three straight meals of Tricholoma equestre, he wrote.

The mushroom, which has a bright yellow cap, is known in the United States as "man on horseback" or "yellow-knight fungus" and in France as "bidaou" and "canari."

Bedry said he confirmed the mushroom's toxicity by feeding extracts to mice and measuring creatine kinase, an enzyme produced during muscle breakdown, in the blood.

The study "raises as many questions as answers, at least in my mind," said Dr. Denis Benjamin, chair of the North American Mycological Association's toxicology committee and author of "Mushrooms: Poisons and Panaceas," a book for physicians.

"I'm not denying that there may be an association. But I think it's very, very far from proven," said Benjamin, a pathologist at Cook Children's Medical Center in Fort Worth, Texas.

There are other mushrooms which have delayed effects, or cumulative toxicity -- and it's rare to find more than one meal's worth of T. equestre, he said.

The article also did not mention tests for other enzymes which are better markers of the muscle breakdown called rhabdomyolysis, or give detailed histories about the 12 patients, he said.

For instance, he noted, strenuous exercise can occasionally cause rhabdomyolysis, and a day of hiking up and down hills and squatting to pick mushrooms might have done so.

"It's unlikely, but it's the kind of information that should have been in the report," he said.

In addition, the creatine kinase increases the study found in mice fed the mushroom extract were small, Benjamin said.

"If you squeeze a mouse too hard while you're giving it the anesthetic, you can cause increases like that," he said.

If the study's conclusions are confirmed, T. equestre apparently would be the first mushroom to cause muscle loss, he said.

"It's one of those intriguing reports one will watch and see if it can be confirmed in the future," Benjamin said.