Yes, hosts used for Mass must contain gluten to be valid matter. However there are low gluten hosts that contain such small amounts of gluten (0.01% gluten) that many persons with celiac disease should be able to receive them. If someone is still unable to receive those hosts then the option exists for them to receive from the chalice. We need to remember that even though the substances of the bread and wine has been changed to the body, blood, soul and divinity of Jesus Christ the accidents of bread and wine still remain.
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