#1

From reading posts in the forum here I see that some studies have potentially linked NAC suplementation to increased incidents of cancer, where the route of action is thought to be an improved mechanism of protection for cancer cells that may already be present.

Most of these posts are late 2022, so I was wondering if there had been any new research or evidence that has come to light in the intervening year to clarify whether this may or may not be correct?

#2

Looks to me like it is being used as an adjunct therapy in treating cancer.

https://scholar.google.com/scholar?as_ylo=2023&q=+NAC+and+Cancer&hl=en&as_sdt=0,29

#3

The clearest and most nuanced I’ve found so far is this:

At low levels, superoxide/H2O2 induce cell proliferation and promote tumorigenesis and progression, and at higher levels they are cytotoxic to cancer cells and inhibit metastasis. Thus, inhibiting ROS could mitigate tumorigenesis and progression while stimulating metastasis. Antioxidants that directly or indirectly remove ROS affect tumorigenesis, progression, and metastasis of tumor cells differently. NAC was shown to exert paradoxical effects in a mouse lung cancer model [17,18]. NAC treatment enhanced metastasis of lung cancer [16,17]. This could be due to decreased oxidative stress in metastatic tumors, causing them to proliferate and grow in distant sites [17]. Pretreatment of melanoma cells with NAC prior to intravenous injection in mice enhanced tumor formation by tenfold [19]. The findings from the mouse melanoma progression model predict that the use of dietary antioxidants or antioxidant therapy might protect against the deleterious effects of oxidants in metastatic melanoma cells, and that the antioxidant therapy is a contraindication for melanoma [19].

(NAC, NAC, Knockin’ on Heaven's door: Interpreting the mechanism of action of N-acetylcysteine in tumor and immune cells - PMC) 2022 Nov; 57: 102497.

Published online 2022 Oct 9. doi: 10.1016/j.redox.2022.102497

PMCID: PMC9563555

PMID: 36242913

NAC, NAC, Knockin’ on Heaven’s door: Interpreting the mechanism of action of N-acetylcysteine in tumor and immune cells

Balaraman Kalyanaraman

2 Likes
Glycine+NAC vs Rapamycin
#4

NAC can inhibit the anti cancer effects of piperlongumine. I have seen a couple of research papers that show NAC could be detrimental to cancer. But the GLY/NAC study on mice gives a completely different picture. Mice are little cancer factories. Most mice die fron cancers, and yet their lifespan is increased in a profound way when they are given GLY/NAC.

Honestly, I don’t know how to interpret this.

“Piperlongumine selectively kills glioblastoma multiforme cells via reactive oxygen species accumulation dependent JNK and p38 activation. Antioxidant N-acetyl-l-cysteine (NAC) completely reversed PL-induced ROS accumulation and prevented cell death in LN229 and U87 cells. In LN229 and U87 cells, PL-treatment activated JNK and p38 but not Erk and Akt, in a dosage-dependent manner.”

https://www.sciencedirect.com/science/article/abs/pii/S0006291X13010292

3 Likes
#5

Time to slam the door shut on this myth. NAC prevents cancer. New study.

“Our investigation offers evidence supporting the potential chemopreventive effects of NAC in individuals with COPD. Moreover, our analysis reveals distinct anti-cancer benefits of NAC, particularly evident in breast, prostate, gynecological, and hepatocellular carcinomas. Notably, the dose-response analysis underscores a consistent trend wherein higher cumulative NAC dosages are associated with reduced cancer risk, emphasizing the importance of dosage optimization in clinical practice.”

4 Likes
#6

Possibly, but this study was on COPD patients, that are far from healthy. Perhaps they get more benefits from NAC. That does not necessarily mean it prevents cancer in healthy humans, although that’s certainly possible.

1 Like
#7

What I was really trying to point out is that it’s more likely to prevent cancer than it is to cause cancer, which has been a silly myth perpetuated all of the internet and on Reddit based on weak rat evidence.

#8

I don’t think that’s a silly myth at all. You can make a reasonable case for NAC preventing cancer but also for it helping cancer grow. It’s a mixed bag and I don’t think we can confidently claim either way what the long-term effect is in healthy people.

1 Like
#9

I disagree. I think this study is good enough evidence that it’s no concern at all. Large sample size too, even if they aren’t healthy.

#10

Some cancer treatments increase ROS in the cell. And If you take large doses of antioxidants during cancer treatment, then the antioxidants might have a negative impact on the treatment.

#11

It’s a study on COPD patients. They are far from a reflection of the healthy population. They suffer from inflammation and oxidative stress and that presdisposes to cancer and NAC is correcting that. In contrast, if you are healthy there isn’t much to correct so you can’t necessarily expect similar benefits. Maybe the same applies to healthy humans. Maybe not. There are far too many examples of things working in diseased people while not working in healthy people to be confident here. So IMO that study is some evidence that NAC might not be of concern for cancer, and as such it gives a bit of peace of mind, but it’s far from conclusive. If it’s enough for you, go ahead and take NAC. In any case, if it turns out it increases the risk of cancer in healthy people over the long run, the effect is likely small.

That’s very true. This is a good example of the saying “nothing is all good or bad”.

1 Like
#12

While I see your points, I think the benefits of NAC are pretty numerous that the very small risk of cancer is similar to being afraid to cross the street because you could get hit by a car. We may have to agree to disagree on this one.

1 Like
#13

Yes. I think it depends somewhat on your age and health status btw. Relatively young people that are very healthy will get much less benefits than someone old or with some disease because a young and healthy person will normally produce high amounts of glutathione. The older you get, the more likely NAC is a net benefit.

3 Likes
#14

Definitely agree here

2 Likes
#15

Thanks for the update. The type of cancer people were worried about with NAC was lung cancer. The study was done in mice.

I’d say this human study trumps the mouse one as it shows no difference in lung cancer rates.

Even though the authors are Chinese, they are actually Taiwanese which probably raises their standard to being acceptable.

1 Like