Is it bad to eat and drink everyday with phosphoric acid in it?

The main way you would eat or drink phosphoric acid would be in soft drinks - primarily colas.

A well-controlled clinical study using calcium-balance methods found no impact of carbonated soft drinks containing phosphoric acid on calcium excretion.The study compared the impact of water, milk, and various soft drinks (two with caffeine and two without; two with phosphoric acid and two with citric acid) on the calcium balance of 20- to 40-year-old women who customarily consumed ~3 or more cups (680 mL) of a carbonated soft drink per day. They found that, relative to water, only milk and the two caffeine-containing soft drinks increased urinary calcium, and that the calcium loss associated with the caffeinated soft drink consumption was about equal to that previously found for caffeine alone. Phosphoric acid without caffeine had no impact on urine calcium, nor did it augment the urinary calcium loss related to caffeine. Because studies have shown that the effect of caffeine is compensated for by reduced calcium losses later in the day. the study concluded that the net effect of Carbonated Beverages-including those with caffeine and phosphoric acid-is negligible, and that the skeletal effects of carbonated soft drink consumption are likely due primarily to milk displacement.