In the classic Star Trek episode, The Trouble with Tribbles, the Enterprise is assigned to protect a shipment of quadotriticale--which Captain Kirk dismissively terms, "wheat."  In exasperation, he exclaims, ""You issued a Priority 1 distress call for a couple of tons of wheat?" Though Mr. Spock patiently points out to him that quadrotriticale is not just wheat, there is no doubt that it contains gluten.

Along with its official cargo, the Enterprise inadvertantly winds up with a shipload of Tribbles, adorable, fuzzy, purring things that do nothing other than eat and reproduce.  At the end of the show, the Tribbles have gotten into the cargo and eaten all the quadrotriticale.  To everyone's shock, most of them are dead or dying.  The conclusion Kirk draws is that the quadrotriticale was poisoned.  But we know better! 

The Tribbles have celiac disease!

Hence, the Tribble has been adopted as our Mascot.