Why don't we make antibody to food whereas oral vaccines are so effective?

Question

I mean how come we make antibody to infectious agents injected orally whereas food eaten orally (also made of the same basic lipids, carbs, peptides) doesn't produce the same immunological response.

Answer 1

sometimes you do, think of allergies. Basically when you are developing you have tons of white blood cells that have some random antibody attached. If that antibody is specific for an endogenous protein in the body, or to something you are exposed to regularly, that cell is either inactivated or killed. Other cells remain dormant until they are exposed to their specific antigen, in which case they proliferate and you get immunity to that antigen.

Answer 2

Because we don't need to. Most organisms that manage to enter the body through the digestive system are broken down by enzymes and the acidic environment of the stomach. Even if they survive this, they must get through the mucosal layer that lines the digestive tract before they can do anything, and they usually get washed away instead. To elicit an immune response, an organism (or a protein or long sugar chain) must reach the epithelial cells of the stomach and digestive tract. Even then, we as humans have evolved the ability to tell what is food and what is not.

Answer 3

Sometimes we do make antibodies to foods, with adverse results. Peanut allergies can be fatal. Allergies to milk or gluten can make persons chronically ill.

I can't think of too many oral vaccines. Polio (Sabin) and typhoid vaccines produce antibodies on the lining of the intestine to reduce viral or bacterial proliferation in the gut.