Coeliac disease sufferers and other people who are sensitive to gluten and other allergens may need to be careful how much xanthan gum is in their food. Some types of xanthan gum are made with wheat, corn or soy and could cause allergic reactions. Xanthan gum is also a strong laxative and can cause diarrhoea in people who eat too much of it, or who are sensitive to it. There are many substitutes available for xanthan gum when used in baking such as guar gum or locust bean gum.