We've had many gluten intolerant/celiac guests in the past who have enjoyed our tours very much. It's true that there are fewer options to eat (bread and breaded meat and fish are very present in Spanish cuisine) but the guide always makes sure everyone has enough dishes to taste. However, and this is really important, even though we communicate all allergies and intolerances to our restaurant partners we cannot guarantee there won't be any cross contamination in the kitchens of the restaurants you'll visit on the tour. Therefore, it really depends on how serious your intolerance is. Most of our guests have felt safe by just taking a pill, whilst for others they may not prefer to take any risk - this is something that only you can assess.