Surfers could be at greater risk of developing an allergy to natto, a Japanese study has found. And the unlikely culprit is thought to be jellyfish stings.
Natto, the sticky fermented soy beans that are as as polarising as Marmite, is a traditional and common Japanese food. Allergy to natto is rare, but research from Yokohama City University Hospital suggests it could be more prevalent in people who spend a lot of time in the water and have been repeatedly stung by jellyfish.
Dr. Naoko Inomata at Yokohama City University Hospital studied the lifestyle habits and sporting history of 18 patients who had been treated for natto allergy at the hospital’s Department of Dermatology since 2004. Of the natto allergy patients, 12 were surfers, two were scuba divers, and one was a professional diver. That means over 80 percent of the (admittedly small) study group regularly spent long amounts of time in the ocean.
▼ Natto allergy is very rare. And the food is really good for you, although it’s not for everyone.
So what’s causing people who spent time in the ocean to become allergic to natto? Well, the substance that gives natto its unique stickiness is polyglutamic acid, which is also found in jellyfish tentacles. So, Dr Inomata believes that repeated stings by jellyfish could cause more surfers and divers to develop natto allergy. “So, if it’s thought that a patient is allergic to natto, doctors should find out if they do marine sports,” she said.
▼ However, taking up surfing just to get out of eating natto is probably a step too far.