This organic acid was discovered by and popularized as a cure for the common cold by Linus Pauling. It was discovered to also have photographic developing powers, although its use in photography is few and far between, but it is a very popular one in holographic developers, being part of the team in some of the standards of the industry such as AAC, CWC2, JD-4, PAAP, SM-6, Nick's #6, and LN-7.
Its anti-oxidant properties enable to stock solutions to last longer without sulfite protection.
It is edible, although tasting some on the tip of a moistened finger may prove painful, as it is a strong acid. But if you do so, you will recognize its taste as being a part of some citrus flavord candies. The Vitamin C capsules available at the apothecary have plenty of starch and sometime sugars to make it more palatable and digestible. These capsules could be used in a holographic developer as the additives have no photographic effect. The tablets weigh more than the marked value on the package because of it; but there is a gram of ascorbic acid in a 100 milligram dose.
Here is what the Photo-Lab Index from Morgan & Morgan has to say about it: