What allows termites to feed on wood, what are the consequences of such nutrition for humans?

Termites feed on the pure cellulose found in wood. It is a complex carbohydrate that is difficult for the body to digest. If a person eats cellulose, then it will come out with feces in an undigested form, so the human body cannot digest this product. Termites have special enzymes in their intestines that can break down cellulose into its constituent components, as well as special bacteria that consume undigested residues. Therefore, termites feed only on wood.