NAC stands for N-acetylcysteine, a supplement widely advertised on bodybuilding web sites as a muscle building supplement and antioxidant. Cysteine is an amino acid and this NAC form of cysteine is supposed to enhance protein metabolism as well as improve the immune system. So says the promotional material.
I could find no scientific support for the value of NAC in bodybuilding, nor has it been tested adequately for safety over the long term when used in this way.
And now a new study suggests it may actually be harmful. Although the experimental study was with mice, three weeks of supplementation with NAC caused dangerously high blood pressure in the arteries that carry blood to the lungs. This condition is called pulmonary arterial hypertension, which can cause swelling to the right side of the heart.
Although the amounts fed to mice were high and further comparisons need to be made with quantities recommended for human supplement taking, this study highlights a caution that applies to supplements in general. Taking nutritional supplements that are untested and unproven for effect and safety is not only a waste of money but can be dangerous.
Source: Palmer LA, Doctor A, Chhabra P, Sheram ML, Laubach VE, Karlinsey MZ, Forbes MS, Macdonald T, Gaston B. S-Nitrosothiols signal hypoxia-mimetic vascular pathology. J Clin Invest. 2007 Sep;117(9):2592-601.
When “reasearch or studies suggest” I would like to know who did the research, when, for how long.
Thanx! carolyne
Hello Carolyne,
I quoted the reference at the bottom of the article.
Cheers, Paul
i didnt know that thank you for the artical i will have to think twice now about if i should use it again
However well intentioned the information was meant to be… it is incomplete and disingenuous. When a comment is made such as
“Although the amounts fed to mice were high and further comparisons need to be made with quantities recommended for human supplement taking, this study highlights a caution that applies to supplements in general.”
… what amounts were fed? What were the controls? I understand the references and if they are to explain my two questions… then what is the use of this article? It sounds like a scare article. If people taking supplements are not aware of what they are ingesting, then they should not take supplements. I would have expected more substance from a person with your background.
Curt, I don’t understand your problem or follow your logic. I posted a short summary of a study about a relatively common supplement used in weight training and bodybuilding — or at least recommended as such. Presumably, this would be of interest to readers. Most would be unlikely to come across this article themselves unless they read the scientific literature regularly, which I do.
I added some comments and gave the reference from the peer-reviewed journal for anyone to follow up on the detail.
As I’ve described elsewhere — and this applies in this short article — there are 4 things that prospective users need to know about dietary supplements:
1. Does it work? Does it do what it says it does.
2. Is it safe? Can you take it without suffering acute, chronic or delayed adverse effects.
3. Are the constituents of the quality and of the quantity listed on the label (if it has a label)? Eg, no impurities or adulterants, hazardous or otherwise, accidental or otherwise.
4. If it has been shown to be safe and effective, is the dose supplied (according to the label) sufficient to produce the effect? That is, no cheating.
NAC has been used for various medical applications and conditions, particularly treatment of acute poisoning by acetaminophen (Paracetamol) and heavy metals; and in lung diseases like cystic fibrosis. Its acute toxicity is low (human LDlo likely in the >1000 mg/kg/bw based on rodent LD50 studies).
However, I could find no relevant studies of mutagenicity (in vitro or in vivo), carcinogenicity, teratogenicity or neurotoxicity in chronic studies in animals or humans. Please post a summary here if you are aware of any.
I found no examples of randomised studies, preferably double blinded, for efficacy as a weight training or bodybuilding supplement. Please let me know if you are aware of any.
Under the circumstances, and considering that supplementation of this kind is often taken for lengthy periods of time, possibly inducing chronic and delayed effects, I thought my article was entirely appropriate. And yes, I do know better
.
Paul Rogers
Paul, the problem is that you imply a negative without any real substantial quantifiable evidence. You cited one study yet cited no positive studies for the supplement.
People should undertand that you are not an expert and that this article was amateur at best.
With that said, everyone is entitle to their opinion.
Bfree
Bfree, I asked for substantiation that this supplement actually works, and some evidence of it’s safety, which is pretty much standard practice in assessing the utility of substances with some pharmacological or biological action recommended for human consumption.
All you have come up with is an ‘ad hominem’ attack, which is, in the end, an admission that you have nothing to offer. However, if you do, here’s your chance to post it.
As to whether I’m an amateur or expert . . . that’s not something you can know.
http://www.ncbi.nlm.nih.gov/pubmed/16458553?dopt=AbstractPlus. NAC looks promising.
jonpft, as I discussed above, NAC is currently used in medical treatment, apparently successfully. This discussion is about it’s safety and utility as an unsupervised, OTC supplement for athletes. First see:
Clin Toxicol. 2009 Feb;47(2):81-8.
Adverse reactions associated with acetylcysteine.
Sandilands EA, Bateman DN.
Second, the utility of antioxidant supplements for athletes is currently under question. NAC has already been reported to act as a pro-oxidant at high doses. In any case, see my article on antioxidants and training here:
http://tinyurl.com/lf9krb
Thanks.
The original comment is very useful. A doctor prescribed NAC drug for one of my firends who is diagnosed PF, a lung desease. Since the NAC drug is very expensive, my friend would like to substitute the prescribed NAC with the cheaper supplementary NAC that is available to buy from internet. Anybody knows the critical difference between the two? Thanks.
NAC improves liver function and is used for paracetamol poisoning to.
I use 600mg of NAC with 1000mg of Vit C, 40mg of Zinc, 3mg of Copper and 3 scoops of Jack3d after a heavy night on the booze and this has definitely helped me to get my arse in the gym and do some bodybuilding.
When I research a supplement I want the facts. Which you gave in the article, but the title suggests an opinion was formed.
Too many writers now days, just for the sake of writing, want to express a positive or negative side associated with a products use, and create an article that the product is good or bad. Almost all supplements can fall into the category of- When takin with this supplement, or when takin without water or without food, or takin too much, they will be harmful for you. Ive read too many articles that are contradicting only bc the writer needed to write an article.
Bodybuilders take their research very serious. And when an opinion is formed off an irrational study we feel its a waste of our time. The correct information presented should have been, High doses of NAC have been found to be hazardous and regular use should be cautioned upon, unless further research can conclude otherwise.
Nate, I thought my headline was appropriately equivocal, and my discussion pointed out all the main features of the research, including a caution. I did not say NAC ‘was’ hazardous in appropriate circumstances, and under medical control.
You are correct to point out that ‘dose’ is an important variable in toxicity. However, over-the-counter supplements are so widely abused these days that a general caution seemed appropriate, in my view. I don’t see a difference between what I wrote and your preferred conclusion.
I agree with this article but have only one reservation. I firmly believe the only true and safe way to dose NAC in through injections. I can testify to the effectiveness of this procedure specifically when injecting NAC (liquid concentrate) into both the anus and the testicles simultaneously. I realize this is a difficult procedure but well worth the effort especially when utilizing a 4 or 6 gauge needle. Numerous studies have shown this to be both safe and effective. Great article!