Antioxidants

[Griffo]

I was suprised that a search for anti-oxidants returned very few results. About the only on topic thread I found simply pointed to an article which is now a dead link.

So.. should divers be on a regular anti-oxidant schedule moreso than the general population? I was thinking about all that oxygen we are exposed to, either by the higher pressures of air, or Nitrox or in accelerated deco. I'm not thinking about CNS Toxicity so much, but about the general damage from the increased level of free radicals.

So, should divers load up on Anti-Oxidants, and if so, are there any in particular that we should look to take. Is it worth loading up the day of or before a dive, or would just a normal routine be best?

 

[Mr Carcharodon]

Most of the oxygen in the body is transported by hemoglobin which is nearly saturated when breathing air at 1 atmosphere. Breathing a higher ppO2 increases the levels of oxygen in solution but overall exposure only goes up by a few percent. Pulmonary tissues can see higher than normal oxygen concentrations however. High ppO2 mixes are desirable not because there is more oxygen than normal but rather because there is less inert gas.

 

[Griffo]

Thanks. While I was across pretty much everything in your post, I didn't fully absorb just how little the total oxygen content of blood increased under increased pressure. I checked with Deco for Divers which shows that the amount of O2 in blood at a ppO2 of 0.21 is 19.8ml per dl of blood, vs 24ml at a ppO2 of 1.5. That didn't make sense at first but I get it now.
Maybe I need to go back and re-read the whole book

(P.S I tried to work out how much O2 would be disolved in blood at 1ATM without hemoglobin and got 0.9ml per dl of blood. That's not much at all! Assuming my maths isn't bunkum)

Thanks for your post.

 

[Mr Carcharodon]

My initial reaction was that hyperbaric oxygen does not increase oxygen levels much beyond the lungs but that does not really explain oxygen toxicity very well does it. So I went back to look here: “Current Thoughts on Mechanisms of Hyperoxic Seizures”, Johnny E. Brian, Jr., M.D. and found this:

“In animals, administration of vitamin E (α-tocopherol) increases the time to hyperoxic seizures, and depletion of vitamin E reduces the time to seizure (23, 25, 42). Vitamin E is an antioxidant that resides in the lipid membrane of cells, and is thought to be important in terminating hydroxyl radical-initiated lipid peroxidation 9 chain reactions. Because vitamin E does not react with hydrogen peroxide, the protective effect of vitamin E could be mediated by reducing hydroxyl radical-induced peroxidation in cells.”

And lo and behold there is experimental evidence that antioxidants help at least with CNS oxygen toxicity. I have not reviewed the references and cannot say how much it helps but there is something there.

 

[DocVikingo]

So.. should divers be on a regular anti-oxidant schedule moreso than the general population? I was thinking about all that oxygen we are exposed to, either by the higher pressures of air, or Nitrox or in accelerated deco. I'm not thinking about CNS Toxicity so much, but about the general damage from the increased level of free radicals.

Hi OzGriffo,

Yes, I think issues along that line are there more meaningful for the diver.

You might find the following a start:

The effects of acute oral antioxidants on diving-induced alterations in human cardiovascular function

Regards,

DocVikingo

 

[Scuba_Shane]

Thanks for those two articles, very interesting