Today I'm introducing a new feature that I hope to make a regular post: Living with Chemicals. As most of you know, I am a chemist (although some of my peers may argue differently). One thing that really bothers me is chemophobia - the fear of chemicals. The term "chemical" has a bad connotation in the media and among pseudo-scientists. They push instead for "all natural" solutions (without realizing that natural does not mean good and synthetic does not mean bad). Unfortunately for them, everything around you is a chemical. In this feature I'm going to be giving examples of "synthetic" chemicals that are good for you, "natural" chemicals that are bad for you, and everything in between.

The Chemical (IUPAC Naming convention):  (3β,5Z,7E)-9,10-secocholesta-5,7,10(19)-trien-3-ol
You probably know it as: Vitamin D
The structure:
 


Vitamin D is somewhat of a misnomer - it's actually not a vitamin. A vitamin is a chemical that is necessary for normal growth, development, and function that is not synthesized in the body. However, vitamin D is synthesized in the body. As shown in the diagram below, when 7-Dehydrocholesterol is irradiated with the sun's ultraviolet light (hν) one bond is broken and another is formed. Cholecalciferol is another name for vitamin D₃.


So, technically it's not a vitamin. It got the name vitamin D because it was discovered while looking for an explanation of rickets - a disease that we now know is due to vitamin D deficiency. Sometimes you'll hear people talk about "absorbing vitamin D" from the sun, but that's not quite true. More correctly, vitamin D is synthesized in your skin using the sun's energy.