Kermie gave me a link and this was on it, so thought i would pass it along...
Researchers at the University of Virginia Health System have discovered troubling side effects of N-acetylcysteine (NAC), a common antioxidant used in nutritional and bodybuilding supplements.
NAC can form a red blood cell-derived molecule called nitrosothiol that fools your body into thinking there’s an oxygen shortage, which can lead to pulmonary arterial hypertension (PAH).
PAH is a serious condition, where the arteries in the lungs narrow, increasing the blood pressure in your lungs, causing the right side of your heart to swell.
Lead researcher Dr. Ben Gaston, noted that this is an entirely new understanding of how oxygen is sensed by the body. As it turns out, your body responds to the nitrosothiols, which are created when a decreased amount of oxygen is carried by red blood cells -- not to the amount of oxygen dissolved in the blood.
So far, studies have only been performed on mice. The next step is to determine the threshold at which the antioxidant becomes detrimental to heart and lung function in humans.