Are you anti oxidant?

A friend shared this image on Facebook.  I thought it was pretty funny, although perhaps not for the reasons its creator thought it was funny:

Okay, anonymous meme creator, I will raise awareness*.

The same process that rusts those chains, oxidation, happens in the human body and in every kind of living cell.  Oxidation happens when an oxidizing molecule takes an electron from another molecule.  Oxygen molecules were the first discovered to do this, and they do it so easily and so frequently that the process of oxidation is named after them, even though molecules without oxygen can be oxidizers as well.

So why is oxidation dangerous?  Because the oxidizing agent is now an anion with an unpaired electron, and that makes it highly reactive.  These molecules, called free radicals - you may have heard of them - are highly damaging to cells, and can cause various diseases, cancers, and are even thought to be a primary cause of aging itself through a process called ‘oxidative stress’.

(Oxidizing agents can also cause combustion. The space shuttle uses oxidation-reduction reactions for fuel and many oxidizing agents are classified as dangerous materials. Generally this kind of combustion requires temperatures or other circumstances too extreme to occur in living cells, although the Bombardier Beetle is an incredibly cool exception.)

When oxygen oxidizes a substance, it produces superoxide, an oxygen molecule with an extra electron.  Superoxide is so damaging and so prevalent that nearly all organisms have a version of superoxide dismutase (SOD), an enzyme which catalyzes (aka destroys) superoxide.  In humans and in most mammals, the production of SOD is regulated by genes SOD1 and SOD2.  Mice with their SOD2 genes knocked out get cancer.  Mice with their SOD1 genes knocked out die around the time of birth.  Mutations in SOD1 are associated with ALS in both mice and humans.

So yes, oxygen is dangerous.  Unfortunately, and obviously, it’s also necessary to survival.  It is like cancer, which arises from the process of mutation without which evolution would be impossible.  They give life, and they take it away.

*Please note I am not an organic chemist and so I may have gotten some of these details wrong.