Question

cellulose is not digested by humans than why it said that some green leaves are good for health

Answer 1

Cellulose is a polysaccharide present in the cell walls of plants and so whenever we consume plant foods we consume cellulose. It serves as insoluble fibre in our diets and is useful to prevent diverticular disease.

Cellulose and starch are two polysaccharides consumed by humans on a daily basis.Both of them are polysaccharides of glucose but have different linkages between the glucose units.Cellulose has beta-1,4-glycosidic linkages , whereas starch has alpha-1,4-glycosidic linkages. In our body, we have enzymes that can break down the alpha-1,4-glycosidic linkages but not enzymes which can break down the beta-1,4-glycosidic linkages.Because of this, humans cannot digest cellulose.

So what happens to the cellulose that we consume? It remains unchanged and acts as roughage, aiding in the smooth working of the intestinal tract. It can be noted here that herbivores like cow have the means to digest cellulose