Hippuric acid in human body?

From what I can gather Hippuric acid is the result of a benzoic acid joining with the amino acid glycene, so I am assuming it is metabolised in the body, I doubt it has any effect unless a large...

decay and burn them in a long time

It depends on the acid and the situation. Sulphuric acid on your skin is disastrous. Oxalic acid in your eyes is soothing. 5% Hydrochloric acid in your stomach is vital for digestion. Ascorbic acid...

Humans obtain the amino acids that their bodies need through the food they eat, particularly foods rich in proteins.

Yes it is and it is found in our digestive system that desolves food for protien.