Medical Expenses are the cost of diagnosiscuremitigationtreatment or prevention of disease and the costs of effecting any part or function of the body.
If you qualify you can deduct the difference between normal food and gluten free food.
You have to save all your receipts and have a certified letter and a prescription from your doctor. The letter has to say that it is medically necessary to eat gluten-free foods.
For a more detailed list look at this link from celiac.com.