Why is citric acid called an acid?

Because it has pH well below 7 (7 is a neutral pH).

@seawulf575 Oh. I thought it would be more complex. Thanks.

Absorbing acid is vitamin C

Just to note: Vitamin C and citric acid are different substances. Vitamin C is also called “ascorbic acid”. They’re similar chemically speaking, but they’re not the same.

I don’t know chemistry too well, but my understanding is that an acid is a substance that gives up a hydrogen ion. When an acid is added to water, it increases the number of hydrogen ions in the solution (that’s what pH measures). A base, on the other hand, increases the number of hydroxide (OH) ions.