Friday, December 30, 2005

When good antioxidants go bad

During a rare naptime retreat, I tried to figure out why exactly antioxidants in large amounts tend to become pro-oxidants. It involves the antioxidant reducing iron (or other transitional metals) from Fe3+ to Fe2+ and the metal being freed up to react with the antioxidant (normally metals are bound to proteins so they are soluble enough to be carried through the bod). As far as I can figure.

For example, Vitamin C helps with the absorption of iron because it can reduce it to the heme state, Fe2+. Iron needs to be heme iron to be absorbed. Too much Vitamin C would mean you
might absorb too much iron -- it might then not have enough transporters and float around free. If that were the case, the iron could react with Vitamin C or other antioxidants, and er, be oxidized. You could rust, I suppose.

Well. It would be easy to be more intelligent than I and have something to offer here (please do). This is just what I'm sort of gleaning from the literature. It caused me to take a nap....and now you'll probably go face down from the excitement too. When you awaken refreshed, you can think of me with gratitude.


Blogger Ilene said...

Ok, ok, when the iron is reduced to Fe2+, it has a role, when free, in generating the dreaded OH radical - the one that causes lots of damage - from superoxide, which generally doesn't. (O(2)(-)+H(2)O(2) -->HO+O(2)+HO(-))

That's the deal. It's called the Haber-Weiss reaction. That Haber, that Weiss, pretty smart.

So antioxidants don't become pro-oxidants, so much as they make transitional metals like iron prime for catalyzing the oxidation of superoxide into the OH radical. My head hurts now.

3:59 PM  
Blogger Txacoli said...

Here's another: the salmon farming industry claiming that the carotenoids they use as dye are actually anti-oxidants (ignore the negative optic nerve effects) and therefore actually better for you than wild fish.

I must be a geek. There are only 3 of us who list Harold McGee as a favorite author.

11:01 PM  
Blogger Ilene said...

Actually, to my knowledge, the salmon farming industry uses annatto, which is a natural antioxidant...however, that does not make it better for you than wild fish.

To my knowledge, there are no optic nerve effects from annatto (but there may be from farmed fish, I have no idea).

For more on annatto, check out this site:

Thanks for dropping by!

11:50 AM  

Post a Comment

<< Home