ucsdhealthsciences:

A sight to C

A polarized crystal of vitamin C (L-ascorbic-acid) assumes the delicate beauty of a snowflake in this micrograph taken by Thomas Deerinck at the National Center for Microscopy and Imaging Research at UC San Diego.

It is an essential nutrient for humans and other animal species, acting, for example, as a protective antioxidant and a key element in numerous metabolic cellular reactions. (It’s necessary to synthesize both collagen and neurotransmitters). It’s also a natural antihistamine.

Most organisms make ascorbic acid internally. There are notable exceptions, such as bats, guinea pigs, monkeys and, of course, humans. People must obtain sufficient quantities from their diet. Peppers, citrus, dark leafy greens are rich in the vitamin. A serious deficiency can result in scurvy, a disease characterized by spongy gums, bleeding from mucous membranes and brown spots on the skin.

The North American Dietary Reference recommends 90 milligrams of vitamin C per day, but no more than 2,000. A healthy, balanced diet typically provides enough without supplementation. Over the years, mega-doses of vitamin C have been touted as a therapeutic or preventive remedy for everything from cancer to coronary disease to the common cold. Supportive evidence is limited and very much in dispute.