Probably the best source for gluten-free or other special dietary foods is the Whole Foods Market in the shopping center between I-4 and Turkey Lake road, just on the South side of Sand Lake Road.
To get there take I-4 in the direction of Orlando and get off at Exit 74, Sand Lake Road. Stay in the left lane and turn left, going under I-4. Ignore the traffic light for the other off-ramp (unless it is red, then stop). The next full intersection is Turkey Lake Road. Turn left here and then make the first available left into the shopping center. Note the Whole Foods Market faces Sand Lake Road.
If you are driving from the airport and want to stop there on the way to WDW, take the Beach Line (SR-528) to where it ends and head in the direction of Orlando. The first exit after you get on I-4 is Sand Lake Road.
