Vitamins and Light

[Mert Avsever]

Hello,

 

First I'd like to say that I'm a newbie on this cool site and it's my first post. We're taught that light has a great impact on certain vitamins and cause them to be destroyed. I know the mechanism of how heat destroys a vitamin, but light sounds different. Well, can someone explain me how light destroys a vitamin? What happens when a vitamin is exposed to light? What reactions? Thank you in advance.

[Josh M]

Nice to meet you, Matt, I'm also new.

 

I don't know the mechanism of how heat or light destroys a vitamin, but I have what I'd like to believe is a simple but mechanically dynamic understanding of the two forms of damage on the skin, which I hope and suspect can be applied to your understanding to derive at least a probable answer. For both heat and light, the damage to the skin is defined by A ) the intensity of the energy (as opposed to the form of energy, even though intensity on a microscopic scale is defined partially by the form of the energy inflicted), B ) the biological defense against the energy (the body sweats more readily in response to heat than to light, produces melatonin only in response to light, and the most vulnerable cells produce the most melatonin, etc...), and C ) the location of the energy (i.e., light rays have the potential to selectively damage portions of the cell, which differs from the more evenly distributed damage of heat waves). Vitamins have no biological defense (correct me if I'm wrong, but I'm fairly confident on this one), and they're not stratified enough for the energy distribution difference between light and heat to be significant (again, correct me if I'm wrong), which leads me to challenge the original premise that any difference between the damage of heat and of light exists.

 

So, I guess our next step (unless I'm wrong or missing something) is for you to elaborate on this part right here:

 

but light sounds different.

 

By the way, this is a fun topic, and I appreciate it!

Edited December 25, 2011 by brodmannstwentysecond

[Jens]

Theory:

Light absorption by a molecule means that one electron is in a hgiher energy orbital after the absorption. The higher the energy of of the light (increasing from red to UV) the higher the energy of the molecule after absorption. This high energy state can lead to chemical reactions which are otherwise not possible and end up in a different molecule which does not act as a vitamin anymore.

However, vitamins are a completly unrelated set of molecules, so the question if light really can destroy a vitamin molecule has to be answered per molecule.

 

Standard textbook knowledge is that folic acid can be destroyed by light.

 

For other vitamins I do not know (some/most of them are surely stable).

 

Research in wikipedia and google scholar might help....