What do you have to do and avoid doing in order that your small intestine is healthy and doesn't catch a disease(also if it is in a list that would be great)

Eat foods that are high in fiber. Fiber helps stimulates the muscles in your small intestine that help you digest food better. Probiotic foods like yogurt as well as fresh fruits and vegetables also help carry beneficial bacteria to your small intestine to help prevent the accumulation and growth of harmful bacteria.