Antioxidants and CNS Toxicity

[AzAtty]

Dr. Deco:

Perhaps this belongs in the "Diving Medicine" forum, but I'll ask it here. I'm wondering if there is a quantifiable benefit to taking antioxidant supplements to help stave off CNS toxicity.

I have read that hydrogen peroxide accumulation (through various chemical processes in the body) appears to be linked to hyperoxic seizures. I have also read that hydrogen peroxide can be reduced to the hydroxl radical, which is reactive and toxic. I also understand that melatonin is the most effective scavenger of the hydroxl radical. Are there any recent studies concerning the effect melatonin on CNS toxicity?

Also, are there any studies of the relationship between reduced glutathione (GSH) supplementation and CNS toxicity?

 

[Dr Deco]

Dear AzAtty:

Oxygen Toxicity

Oxygen is a substance that is toxic in our body, even at one-fifth atmosphere pressure, but at the same time it is required for life processes, viz, oxidative metabolism. The cellular damage is the result of the formation of reactive oxygen intermediates released from the mitochondria during normal oxidative metabolism.

Protective agents that occur naturally in the cells hold this damage in check. Among these are the well-known oxygen free-radical scavengers such as catalase, superoxide dismutase, etc.

Supplements and Diving :upset:

In this category, we have two cases to consider when a diver asks the question. The first concerns supplements while diving to protect against oxygen toxicity. The only case of which I am aware of when this is routinely done is in some hyperbaric medical facilities. Here, patients under treatment with two to three atmospheres of oxygen administered once of twice a day are recommended to take vitamin E and vitamin C. How effective this is, I do not know, as seizures are rare even in the absence of these adjuncts.

I can well imagine that there are divers who are taking large doses of vitamin C and E. I am not aware of any controlled studies in this area. There are demonstrated effects of the administration of superoxide dismutase with respect to oxygen toxicity, however, this enzyme is digested in the stomach and is not effective orally but rather only when injected into the blood stream. About fifteen years ago it was sold in divers’ magazines for CNS toxicity in a tablet form for oral administration.

Glutathione is well recognized as an antioxidant, but I do not know if it effective orally. Melatonin is another antioxidant. Many use it for a sleep aid and time-shift adjustment. I am not aware of trials of this for CNS protection in diving.

I really doubt that relying on these materials by divers is a particularly good way to stay out of trouble with CNS oxygen toxicity.:boom:

Nondiving Issues and Supplements

This is a different area altogether. Many people (I included) do take daily supplements of vitamins C and E for protection against oxidative stress. It is very common. To my knowledge, it does have a salutary effect on the aging process.

Dr Deco :doctor:

 

[Hamster]

If my understanding is correct exposure to elevated PPO2 gives rise to an increased number of free radicals. If this is true then are there any long-term effects upon the body. I am not talking about oxygen toxicity but rather accelerated aging or some other long-term effect.

 

[Dr Deco]

Dear Hamster:

Reactive Oxygen Species :boom:

Reactive oxygen species (ROS) and other radicals are believed to be involved in a large number of biological phenomena. They can cause mutations, produce cancer, degenerative diseases, inflammation, and aging. These are more easily demonstrated in short-lived animals than in humans. Thus fruit flies live for a shorter duration in increased oxygen than those kept in lower partial pressures. Obviously, such a study has not been done with humans.

Long-term Effects Of Oxygen

In so far as the free radical theory is correct (or at least some aspects of it), the production of free radicals is not a salubrious event in our cells. In a perfect world, the free-radical scavengers would clean up the miscreant molecules and the story would be over. Alas, it is possible that some radicals escape capture. (This sounds like some spy story.)

Exogenous Scavengers

To assist the cleanup process, many individuals ingest scavengers. These might be in the form of vitamin C and E and melatonin. The degree of success of all of this is not known .

Catch Twenty Two

It seems as though too much oxygen is bad for you and none is no good at all. I am certain that God was in a good mood the day He made oxygen, but it is a two-edged sword. It is similar to having too much chocolate – no, wait, you can never have too much chocolate. :mean:

Dr Deco :doctor:

 

[CheeseWhiz]

I asked a related question in the "Diving Medicine" section some time back: are there any contra-indications to taking vitamin E and diving?

I was thinking along the lines of the blood thinning which accompanies vitamin E causing a problem.

Dr. Campbell said that as long as the thinner blood didn't lead to symptoms such as nose bleeding, there should be no problem.

I realize this diverges somewhat from the original question, but it's perhaps relevant enough to be worth at least 1.5¢.

 

[Hamster]

Rather than spend money on supplements the answer might be just to eat plenty of fruit and vegetables.

 

[CheeseWhiz]

If the world were a perfect place, we would all eat a perfectly balance diet and get 100% of everything we need for a long and healthy life.

In my world, however, I don't have time to weight out how many grams of this or that I'm eating, what % if saturated fat, what % is un-saturated, how much carbs, blah blah on and on.

To further complicate matters, I travel a good bit, and when eating at restaurants, even ones with healthy menu choices, it's virtually impossible to maintain a constant input of whatever it is that you think you need.

So, in order to be ensured of getting all of what I think I need, pills are the way to go.

But you're right Hamster....since I'll like so much longer from taking the vitamins, the cost will add up over the years.