As someone who has lived in Japan, and moved to Japan without much prior language experience, I know how daunting it may be to get yourself situated properly there. On top of this, if you have Celiac Disease, gluten intolerance, or you need to follow a gluten-free diet for other autoimmune diseases/issues, being able to know what is in the foods there can seem daunting. In prior posts, I have recommended that you obtain gluten-free travelers cards that list foods in Japanese and English. This helps the Japanese chefs (or anyone who may be helping you navigate Japanese cuisine safely) know what you can and cannot eat. One thing that I remember facing over and over again while living in Japan was the question, “But what can you eat?” This was almost always after I told them that I couldn’t eat wheat, barley, oats, rye, or anything that was derived from these grains. Of course, we can eat quite a bit of food and most of it is very good food for us (in some ways, if we’re following a whole foods paleo/primal-like diet, we’re ahead of the pack, in terms of eating healthy), but in this modern era, most prepared foods have some form of gluten in them. Unfortunately, this goes doubly so in Japan.
I’ve written before about hidden sources of gluten in Japanese food. Soy sauce is obviously one of the main culprits that make enjoying Japanese food difficult for us. Another source comes from hidden starches in the form of でん粉 or でんぷん (pronounced denpun) as thickeners and fillers. The source that often trips those of us up the most though is アミノ酸 (aminosan), the Japanese term for MSG.
アミノ酸 is a flavoring that is used to create umami in a number of foods. A fellow JET who lives in Japan wrote an informative article about its history. It’s what gives convenience store onigiri their particular flavor (and I’ve written before that you should avoid these like the plague for this reason, even if someone tells you that they don’t contain wheat/gluten). I’ve had long discussions with people about this who will tell me that アミノ酸 does not have gluten in it, will proceed to eat salmon or umeboshi onigiri that are seemingly wheat-free on the label, but then write to tell me that they’ve somehow mysteriously been glutened. Sometimes it takes bad experiences to be able to learn, I guess. I do not recommend taking such risks while you’re traveling through Japan though, unless you want to have a miserable experience.
アミノ酸 sometimes comes in the form of salt at restaurants and can be used in anything that you consume at restaurants. For example, I once went with friends to a steak restaurant. After showing him my card, the chef seemed willing and ready to create a meal for me. He went through all of his ingredients and said they were safe, but on double checking, he realized that a herb seasoning that he’d created also included アミノ酸 in it. If he hadn’t gone back to inspect all of his ingredients, the meal would have contained gluten and I would have left there with a meal that was on its way to making me feel unwell.
I’ve had another experience where I’ve asked for table salt and it’s come in the form of Ajinomoto (味の素株式会社) salt-like seasoning and I’ve mistakenly used it to season my foods with. Be aware of this form of gluten in Japan, because the majority of Japanese (including anyone cooking your food) do not realize that it contains gluten in it.
My recommendation is that you cook your own foods unless you find a restaurant this has a dedicated gluten-free kitchen or one where you’ve come to know the chef and trust them to prepare food for you.
Good luck with your culinary and cultural adventures while living and visiting Japan.