NAC antioxidant may cause harm

[trux]

I guess this the article A type of antioxidant may not be as safe as once thought at Physorg.com could be worth of looking at for anyone interested in freediving physiology, and also for those using diverse nutritional supplements and antioxidants:

Certain preparations taken to enhance athletic performance or stave off disease contain an anti-oxidant that could cause harm. According to new research at the University of Virginia Health System, N-acetylcysteine (NAC), an anti-oxidant commonly used in nutritional and body-building supplements, can form a red blood cell-derived molecule that makes blood vessels think they are not getting enough oxygen.

This leads to pulmonary arterial hypertension (PAH), a serious condition characterized by high blood pressure in the arteries that carry blood to the lungs. The results appear in the September issue of the Journal of Clinical Investigation.

What might be interesting for better undestanding of the physiology in apnea is the following paragraph:

“NAC fools the body into thinking that it has an oxygen shortage,” said Dr. Ben Gaston, UVa Children’s Hospital pediatrician and researcher who led the study. “We found that an NAC product formed by red blood cells, know as a nitrosothiol, bypasses the normal regulation of oxygen sensing. It tells the arteries in the lung to ‘remodel’; they become narrow, increasing the blood pressure in the lungs and causing the right side of the heart to swell.”

Gaston notes that this is an entirely new understanding of the way oxygen is sensed by the body. The body responds to nitrosothiols, which are made when a decreased amount of oxygen is being carried by red blood cells; the response is not to the amount of oxygen dissolved in blood. He says that this pathway was designed much more elegantly than anyone had previously imagined. “We were really surprised”, he said.

 

[efattah]

Very interesting! I experimented with NAC for freediving years ago, and generally found positive results, and now it is clear why. The article basically says that it should cause the dive reflex to kick in, without even diving.... So, hypothetically, taking a large dose of NAC would initiate hypoxia defense mechanisms, even before hypoxia begins. This could be useful for performance reasons, although not necessarily helpful in the long-term.

 

[trux]

The article basically says that it should cause the dive reflex to kick in, without even diving....

Yes, exactly. However, I am afraid that besides the potential negative long term harm (pulmonary arterial hypertension), it can have negative effects at serial serial diving too. I imagine that not allowing the body to recover from the permanent blood shift may take its toll. Also the higher load and the swelled heart may possibly lead to a quicker exhaustion of the organism, and the permanent pulmonary hypertension also likely reduces the maximal lung volume (though, on the other hand, it makes the gas exchange more efficient).

 

[OceanMan]

Makes me think about this thread
http://forums.deeperblue.net/safety/60421-freediving-dangerous-2.html

There seems to be several pieces of evidence now that hard apnea training may cause permanent pulmonary hypertension.

:hungover

 

[DeepThought]

Pulmonary hypertension can also lead to pulmonary edema (as in some acute altitude sickness cases). But there's also an issue of quantities...