Hidden Gluten in Japanese Food: A Celiac Traveller's Master List

The hardest part of eating gluten-free in Japan isn't the obvious bread — it's the wheat hiding in soy sauce, miso, tempura batter, curry roux and some dashi granules. Regular shoyu (soy sauce) contains wheat, so most simmered and glazed dishes are off-limits unless confirmed. Lean on naturally rice-based foods, carry tamari, and always verify shared fryers and shared pasta water.

Where wheat hides (the danger list)

• Soy sauce (shoyu) — brewed with wheat. This is the big one: it flavours teriyaki, gyoza dipping sauce, glazes, marinades and countless simmered dishes. Tamari is the lower-wheat cousin, but many tamari brands still contain some wheat — check the label. More on this in is soy sauce gluten-free in Japan.
• Miso — most is soy-and-rice based and fine, but mugi miso (barley miso) contains gluten, and some blends add barley. Ask.
• Tempura & anything fried — batter is wheat flour. Even "clean" fried items share fryer oil with breaded things. See tempura.
• Breaded katsu, korokke, menchi-katsu — panko is wheat bread.
• Curry roux — Japanese curry is thickened with a wheat-flour roux. Almost always contains gluten.
• Soba — buckwheat is naturally GF, but most restaurant soba is cut with wheat flour (ni-hachi = 20% wheat). Only 100%-buckwheat (juwari) shops are candidates, and even then the water is often shared with wheat noodles.
• Imitation crab (kani-kama) — usually contains wheat starch.
• Dashi granules & instant stocks — some contain wheat; freshly made katsuo/kombu dashi is usually safe.
• Malt vinegar, some ponzu, some mirin blends — check.
• Beer and mugi-shochu (barley shochu) — contain gluten. Rice-based sake and imo (sweet-potato) shochu are naturally GF.

Naturally gluten-free foods (the safer list)

• Plain steamed rice, onigiri (with GF filling, no soy glaze)
• Sashimi (bring your own tamari — the house soy sauce is wheat)
• Yakitori cooked with shio (salt), not tare (soy glaze)
• Grilled fish seasoned with salt
• Most mochi and rice crackers (but confirm — some are soy-glazed, and cross-risk exists)
• Sake and imo-shochu

Rice is your best friend here; when in doubt, choose rice-based and salt-seasoned.

Cross-contamination: the invisible trap

There's a real difference between a dedicated gluten-free kitchen and a place offering a "GF option" from a shared fryer, shared grill or shared noodle water. For celiac disease, shared equipment is a genuine risk, not a rounding error. Ask specifically: senyō no abura desu ka? (is the oil dedicated?). We never call a place "celiac-safe" unless it's a fully dedicated GF kitchen.

Eating with more confidence

Tokyo has a small but real cluster of fully dedicated gluten-free kitchens where cross-contamination isn't a worry — worth planning your day around. For the full mapped list and neighbourhood clusters, see the gluten-free Tokyo guide and the broader gluten-free Japan travel guide, plus our gluten-free directory.

Japan rewards preparation. Learn the danger list, carry tamari, favour rice, and confirm shared equipment — and you can eat genuinely well.