Cancer patients should NOT take N-Acetyl-Cysteine!

March 10 2011 post. I subscribe to a very informative, well-researched, full of common sense (etc. etc. etc.) newsletter written by Jacob Schor, President of the Oncology Association of Naturopathic Physicians, with his own practice in Denver (see:

His most recent article (see concerns N-Acetyl-Cysteine, = NAC for short, which, he shows, cancer patients should NOT take under any circumstances, essentially because it helps cancer cells stay alive. Eeek, that is the opposite of we want! As if that were not enough, NAC also blocks the anticancer activity of several substances, including green tea (EGCG), selenium, vitamin D3 AND, last but never ever least!, curcumin (see Phew, I am so very glad I have never taken any of this stuff…

Well, among other things, Jacob’s article explains the glutathione process in cancer in an easy-to-comprehend manner, so please have a look…especially if you have cancer and take NAC for your winter colds and flus…

29 thoughts on “Cancer patients should NOT take N-Acetyl-Cysteine!

  1. Joy

    This is absolutely fascinating. I have Multiple Chemical Sensitivity, and one of the main things that is said to help that condition is glutathione, so I have often tried that supplement, or tried ways to increase it. The minute I read this article I went straight to the cupboard and threw it all down the drain and into the bin!

    THANK YOU Margaret for posting this! You are a gem, I cannot believe how many relevant articles you have here to discover. With the help of all this information, I am going to beat this MGUS and not have MM!

  2. Mel

    I’m so glad you posted this. But argh! What a bummer. You might remember my dog Maggie with MM – thanks to the melph, pred, tons of curcumin, and other supplements, her bloodwork is great 2 years post DX (no signs of it in the bloodwork at all). She’ll be 14 in October. But now she has chronic bronchitis. Bronchial meds help control her infrequent cough, but not the mucus or heavy breathing. I found this and was excited – was researching whether or not it would be OK with melph and her supplements. Thankfully I found your post! Guess we go on to the canine inhaler (seriously). I don’t want to increase oral pred if I can help it (she’s still on half the recommended dose for MM and rockin’).

    Anyone know any good supplements for chronic bronchitis??

    ? Mel

  3. everet

    Sure got some negative things happening with cysteine; however, wouldnt the postive things be good if one was using immuno-therapies ??:
    N-acetylcysteine (NAC) generally improves the bodys immune system, making it better able to fight off disease.
    In their 1992 review article Staal et al reported that “adequate levels of GSH are required for mixed lymphocyte reactions, T-cell proliferation, T and B cell differentiation, cytotoxic T-cell activity, and natural killer cell activity. Decreasing GSH by 10 to 40 percent can inhibit completely T-cell activation in vitro. Thus, an intracellular GSH deficiency in lymphocytes has profound effects on immune functions.” Staal FJ, Ela SW, Roederer M, Anderson MT, Herzenberg LA, Herzenberg LA. Glutathione deficiency and human immunodeficiency virus infection. Lancet,1992;339(8798):909-912.
    (gotta have some of the immune help)
    The thiol N-acetylcysteine (NAC) is a promising cancer chemopreventive agent which acts through a variety of mechanisms, including its nucleophilic and antioxidant properties. We have recently shown that NAC inhibits type-IV collagenase activity as well as invasion, tumor take and metastasis of malignant cells in mice. (though NAC works on dose-wise basis, would its use make up for possibly negating curcumin’s, green’s, etc’s anti-collagenase activity by providing its own??)

  4. Mike

    Margaret, What do you think of these studies. Perhaps the production of glutathione by NAC is not as bad as we thought. Inhibiting NF-KB, COX-2, and cytokines can’t be all bad.

    Dr Schor states that NAC is quickly taken up and converted to glutathione in the body. The first study above shows that the mice were given NAC in drinking water. Do mice convert it to glutathione? From what I can find, they do. It brings up the question. Is NAC or glutathione providing the benefit?

    In the tests showing the decrease of curcumin viability, the cells were pretreated with NAC in vitro. So, does it matter it was not introduced in the body where it would be a precursor to and converted to glutathione? what is presented alot in the pages I looked up is that glutathione levels are greatly reduced in cancer patients. If this is true, I should think it needs to be increased rather than avoided.

  5. edwina

    I have been taking NAC for the last 2 weeks after reading such positive reviews from people with a similar problem to mine. I recently had pneumonia and my blood and sputum tests showed a mild level of aspergillus mold. I have autoimmune related conditions and am also taking curcumin and various other supplements.

    After recently having had a regular mammogram I have been recalled for further testing and after reading the negative comments regarding NAC and cancer, I think I should stop the NAC? Any comments please?

  6. Joy

    My Naturopath, who is also part of the same naturopathic oncologist organization Dr. Schor is head of, has specifically prescribed NAC for me, along with curcumin and green tea extract, etc. I am seeing him in a few days and going to show him the article and ask him specifically about this, as Dr. Schor’s comments are the only place I have ever seen anything less than positive about NAC and cancer. Many other alternative cancer doctors recommend it. I will report here what he says. If he says to keep taking it I will unless my markers go up (they are currently going down).

  7. Terea

    Margaret where would we be without you!
    You said you are a Teacher, I think we’d all
    agree you are more like a Professor for us! :)

  8. Big Al

    I had read some good things about NAC and bought a bottle of 50 capsules a few months ago. During that time my MM remained steady. (Kappa Free Light Chain)I just bought a new supply and will surely monitor my numbers closely.

  9. Jane

    I want to take Taurine but it is always listed as following a cysteine path. Does anyone know if it is safe to take if you have breast cancer? I can’t find anything about it concerning breast cancer on the net. I did see it in connection with NAC. I don’t take NAC but I do take curcumin and several other supplements.

  10. R Cannon

    I saw something about NAC protecting cancer cells when grape seed extract was given, which was killing the cancer cells.

    “Consistent with these results, GSE treatment resulted in a strong DNA damage, and a decrease in the levels of DNA repair molecules Brca1 and Rad51 and DNA repair foci. GSE-caused accumulation of intra-cellular reactive oxygen species (ROS) was identified as a major mechanism of its effect for growth inhibition, DNA damage and apoptosis, which was remarkably reversed by antioxidant N-acetylcysteine”. Don’t know the details.

  11. Ron

    R Cannon

    That is a nice abstract on the GSE, I did check and curcumin has these same actions on Brca1 and Rad51. These phytonutrients are certainly getting interesting.


  12. Berner

    I think the statements about NAC contradict the new understanding of the metabolism and the interactions between cancer cells and the fiberblast stroma. You can look up the articles about the “reverse warburg effect” to read more about it. NAC will primary not protect the cancer cells but the fiberblasts from being “misused” by the cancer.

  13. Big Al

    “Berner” do you take NAC? If so, why and is it helping you? I’ll check out the link you posted, thanks.

  14. Andrew B.

    So bottom line is it good or bad for cancer? This doctor cannot be found in Google Scholar and many studies say otherwise. Perhaps we shouldn’t draw conclusions based on a single paper. Can anyone corroborate Shor’s assertions and his reputation?

  15. Andrew B.

    So I’ve read some more and I’m not convinced. So some scientists found that increased ROS through some mechanisms (which is actually damaging to the organism) has the potential of killing cancer cells and that NAC blocks the effects of this medication. I don’t see this as a reason for anyone not to take NAC – unless they actually rely on ROS destroying their cancer cells.

  16. Andrew B.

    Oh Margaret, now I’m seriously doubting that doctor. He talks about a paper saying that Ginseng’s anti-cancer effects are rendered useless by NAC. I assume he’s talking about this paper which actually states the opposite:

    Both in the title and in the body of the paper: “NAC blocked S4h-induced ROS and increased S4h-induced apoptosis. In conclusion, all these results showed that the high level of ROS in S4h-treated colorectal cancer cells protected these cells from undergoing apoptosis.”

    So what gives?

  17. Andrew B.

    Sorry for the many comments, but I’m really interested in this topic. Apparently Schor talks about a different paper that states actually the same thing: “Furthermore, we show that Rh2 increased ROS levels and activated the NF-?B survival pathway. Blockage of ROS by NAC or catalase inhibited the activation of NF-?B signaling and enhanced Rh2-induced cell death, suggesting that the anti-cancer effect of Rh2 can be enhanced by antioxidants.”

    So… this doctor actually has in the references a paper saying the opposite of what he’s saying? And to my knowledge, NAC is no different from any other anti-oxidant including Vitamin C in this regard (reducing ROS). So are we supposed to drop all anti-oxidants?

  18. Andrew B.

    Some conclusions, after some more thinking:

    1.) All antioxidants reduce ROS
    2.) NAC being the King antioxidant, it is used in laboratory settings to inhibit ROS for various purposes
    3.) Treating cells in a laboratory setting with NAC may not be the same thing as taking NAC orally in much smaller doses

    You may comment on my above conclusions if you feel like it.

  19. Greta R.

    Dear Andrew B.
    Thank you for your research, diagnosed with breast cancer. I’ll go with NAC. It’s like 99.9% of good things against this one article.

  20. Ruth Feldman

    From what I have read, NAC can help you avoid cancer. However, if you already have cancer, don’t take NAC because it helps all the cells even cancer cells. NAC is such a valuable substance, it is counterproductive to encourage people to throw it away. That proves the saying that a little bit of information can be a dangerous thing. I suggest that the readers Google NAC benefits to find out for themselves rather than panic and behave foolishly.

  21. daisy

    How would this relate to MTHFR Mutation, since those with mutation have reduced gluathione levels? I have MGUS and my B12 shows levels in 200′s, but I also had lyme. Lyme patients seems to benefit from infusions of glutahione however, I know the lyme triggered the MGUS it happened shortly after exposure. And this is a known contributer albeit hush hush among oncologists. Lots of people in the lyme forums testing for MGUS, as the lyme docs run the immune tests and finding it. Curious if the low gluthat might actually help the cancer stay away if taking curucmin? Anyone with science knowledge that could address this question and explain it for a novice? thanks,

  22. beatrice nordberg

    I have been taking 500mg of NAC for at least 3 years after a serious lung infection. So far my MGUS is holding steady. I will continue using it.

  23. debbie

    Expellation is not a word dude. The word you are looking for is expectoration. hmmmm….makes me wonder about his research a bit.

  24. Katherine Morgan

    Please tell me what NAC is…I have smoldering for over 5 years now. DR. durie says that is most probably won’t progress after 5 years… Does anyone have the facts on this?
    Thank you,
    Katy Morgan

  25. Dorit Arad

    In addition to the research studies by Michael Lisanti on the role of NAC in reversing the metabolic pathway of the fobroblasts that feed cancer cells through autophagy, I found an old function of NAC that was a bit forgotten. NAC acts as a strong inhibitor of collagenases, among which colagenase II -IV have important role in invation, particularly in gastric cancer.
    see: J Cancer. 1996 Sep 17;67(6):842-8. Synergism between N-acetylcysteine and doxorubicin in the prevention of tumorigenicity and metastasis in murine models. De Flora S1, D’Agostini F, Masiello L, Giunciuglio D, Albini A.
    So I think that NAC is good for cancer patients


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