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Actually, free-radicals, and the damage they cause, was what my PhD was all about.
Yes, increased ppO2 will result in increased production of oxygen based free-radical species, or as we more commonly call them ROS (reactive oxygen species).
Yes, making sure you've got a reasonable amount of antioxidants in your system will help: not only Vit E but Vit C, as well as the massive range of plant derived compounds (eg polyphenolics, these are probably more important according to current research).
However, breathing normal air (whether you're diving or not) also produces ROS; about 1-2% of the O2 taken in is turned into ROS, mostly by your mitochondria(the 'powerhouse' of your cells). This figure increases if you're 'working out' really hard (health fanatics take note!)
Techno-babble aside, it has been calculated that the bits inside every cell in your body (ie proteins, lipids and nucleic acids) are hit by between 45 - 450 ROS every second of the day! Consequently, you have to think in terms of relative quantities of ROS and relative indices of cellular damage.
Excess production of ROS (or inability to cope with this) is believed to be the cause (or causative mechanism) underlying a massive range of human conditions: cancer, Alzheimers, Huntingdons chorea, AIDS and even jet lag!
BUT...ROS aren't all bad - your white blood cells use them to keep you healthy by killing bacteria. And all those crazy rich folk that think they'll live forever if they can only get enough antioxidants inside them, well... taking too many is just as bad as not enough!
Now I don't want to worry anyone, but all the factors which predispose divers to DCI (changes in ppO2, dehydration, being overweight, smoking etc), have also be linked to excess production of ROS.
However, there is as yet only a little evidence to demonstrate that diving on normal air does actually increase the amount of free-radicals; a recent publication showed that the amounts of molecules involved in inflammatory responses (fevers etc.) were increased
with regular diving (using military subjects).
Unfortunately our DDRC doesn't have the funding for researching ROS-mediated effects of diving (I know because I asked them!) but they are interested in this topic.
If anyone wants to know more about the effects of ROS in terms of our health, I'm happy to explain whatever may sound too technical but the take home messages are:
1) we need O2 but it's a double edged sword - it is what makes us grow old and die.
2) You cannot avoid ROS and they aren't all bad
3) Diving nitrox (as per the intructions during your course) won't make a bit of difference to your overall level of ROS mediated damage
4) If you want to make sure you're not generating too many ROS, you can: avoid smoking, avoid strong coffee and eat plenty of fruit and veg. Also, eggs are a good source of antioxidants as are fried tomatoes (best done in a little olive oil) and of course a glass or three of red wine is believed to do wonders, but not before diving.
Chee-az
Steve
PS just in case anyone thinks I'm some kind of "biochemical puritan", I'm happy to dive nitrox, I drink strong coffee and have the occasional tobacco based product.  |