# Why is vitamin C called an antioxidant?

According to Wikipedia, vitamin C (ascorbic acid) "may also act as an antioxidant against oxidative stress," and is "widely used as a food additive, to prevent oxidation." But acids are, by definition, oxidizing agents, so how is it that ascorbic acid is used to prevent oxidation?

• Most acids (except nitric and some others) have nothing to do with oxidation. Well, I mean, they may oxidize metals, but we are not made of metals. Feb 19, 2016 at 17:57
• I dispute your claim that acids are oxidising agents. $\ce{HI}$ is a fairly strong acid that finds use as a reducing agent.
– bon
Feb 19, 2016 at 19:25