<<Disclaimer: Verify this information before applying it to your situation.>>

I was just looking over a 7 language sushi directory I have, and noticed a couple pages of useful phrases.   Here are some short & simple sentences that might be easily printed or memorized in the following languages.  I hope this is helpful.  If you need a phrase for vegan, please email me and it will be sent to you.
Janet in Modesto, CA
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I don't eat wheat gluten.

Japanese        O-fu wa tabemasen.
French            Je ne mange pas de gluten de ble.
German          Ich esse kein Weizengluten.
Italian             Non mangio glutine di grano.
Spanish          No como gluten de trigo.
Portuguese     Nao como gluten de trigo.

Due to the many allergies, I have included this as well:

I don't eat shellfish.

Japanese       Kai wa tabemasen. 
French           Je ne mange pas de crustaces.
German         Ich esse keine Schalentiere.
Italian            Non mangio molluschi.
Spanish         No como mariscos.
Portuguese    Nao como marisco de concha.

*Please provide references to back up claims of a product being GF or not GF*