The relevance of this answer to your question really depends on what forms of phosphoric acid you are refering to.
The largest percentage of a form of phosphoric acid, I understand, is in the form Pi (Inorganic Phosphate), which is essential for nucleic acid synthesis, is a component of ATP, and makes up70 % of bone tissue.
Inorganic phosphate also is important in the maintenance of the Calcium/phosphorous homeostasis, which is regulated by reservoirs of calcium and phosphorous in the bones, intake of these substances in the GI tract and expulsion from the kidney.
If your question reguards soft drinks, studies have indicated that the phosphoric acid levels from drinking to many soft drinks may lead to osteoperosis and may amplify other bone loss disorders.
😀 My apollogies for the brain dump I just left on your computer😛