Harmful reactions caused by mushrooms
Trehalose intolerance: abdominal problems due to mushroom sugar
Mushrooms contain trehalose, mushroom sugar. To break it down, an organism needs trehalase, a digestive enzyme. Some people lack this enzyme and are unable to absorb mushroom sugar. As a consequence, abdominal problems will start hours after eating. The symptoms of trehalose intolerance resemble those in lactose intolerance connected with milk consumption. Trehalose intolerance is rarer than lactose intolerance. If abdominal problems keep occurring after mushroom meals, trehalose intolerance is one possible reason for it. If trehalose intolerance has been diagnosed, the treatment consists of avoiding mushroom products to the extent that symptoms won't occur.
Cultivated mushrooms, including oyster mushroom (Pleurotus ostreatus), Agaricus species (cultivated mushroom, (button mushroom)) (Agaricus bisporus) and shii-take (Lentinus edodes), can cause occupational allergies. Mushrooms can also sensitise a person the way pollen and food allergies do.
Handlers of ceps (Boletus) have presented cases of allergic rhinitis and asthma as well as anaphylactic reactions. Ceps also contain albumin, which the enzymes of the digestive system cannot break up. For people who are sensitive to these kinds of mushrooms, some of the consequences can be swelling and itching of the mouth and abdominal problems. Trumpet chantarelle (yellow foot) (Cantharellus tubaeformis) has been found to cause food allergies with abdominal symptoms and oyster mushroom species (Pleurotus) allergic symptoms in respiratory passages. However, so far there is fairly little information available on allergic respiratory passage symptoms caused by mushrooms.
Shii-take and other oriental mushrooms have caused contact dermatitis, cough, flu, sneezing, asthma and alveolitis. The statistics of the Finnish Institute of Occupational Health puts shii-take on the sixth position in the list of plants causing asthma and allergic rhinitis.