Question

why is cellulose in our diet not nourishing ?

Answer 1

cellulose is composed of glucose in monomer units. but humans can't digest cellulose because human body doesn't have those bacteria and don't secrete those enzymes that break down cellulose molecules and give glucose units. thus cellulose is not nourishing for our diet.

Answer 2

cellulose is not nourishing in our diet because cellulose has beta acetal linkages which is only broken down to digest by appropriate enzymes which are lacking in humans.Whereas cows who eat grass has the enzymes which can do the breakdown of beta acetal linkages and help the cow to digest it.That's why cellulose in an human diet is not nourishin as it takes a lot of time for the human body to digest one bite of cellulose.