Gut Health: Biofilms, N-acetylcysteine and H. Pylori

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Many infectious agents can form biofilms that lead to increased resistance to antimicrobial treatments. This article will discuss some recent research pointing to the anti-biofilm potentials of the supplement N-acetylcysteine, or NAC, including possible improvements in treatment for particularly recalcitrant infections like Helicobacter pylori.

As I’ve previously written about, biofilms are formed by a range of different life forms. A good way to think of them are like little cities with a multitude of different species and organisms within those species.

The concept of biofilm formation is not new and appears in the fossil record as far back as 3.25 billion years (2).

The contribution to disease and infection holds that the formation of biofilms work as protective structures that lend antimicrobial and immune mediated defence (3).

So in short, biofilms are an ancient strategy for microbial communities to aggregate, colonise a niche and form a protective layer against intruders. It is worth pointing out that this is not always a bad thing, just when biofilms are implicated in infections leading to reduced treatment success.

Failing Antibiotic Treatments – Are Biofilms to Blame?

Without considering biofilms many conventional treatment options for resistant bacterial infections, including Helicobacter pylori, include two and sometimes three antibiotics given simultaneously and often combined with proton pump inhibitors (acid suppressing meds.)

Even these heavy hitting therapies are starting to fail, coming close to, or not meeting the 80% success rate that is considered the minimal acceptable levels (2, 4, 5).

N-acetylcysteine (NAC) Anti Biofilm Agent?

Continuing on with improving Helicobacter pylori treatments one study looked at the effect of N-acetylcysteine on breaking down H. pylori biofilms.

The in vitro part of study looked at biofilm degradation of H. pylori cultures with NAC and without

  • First they isolated strains of Helicobacter pylori from 10 different patients with 4 failed eradication treatments – so here we are talking about tough to kill bacteria!
  • Then they cultured the bacteria and compared the difference between biofilm formation on plates enriched with NAC and those without in varying amounts (2, 10 and 20 mg/ml)
  • The plates cultured with the smallest amount of N-acetylcysteine (2 mg/ml) failed to form biofilms
  • Compared to the plates without N-acetylcysteine that did – All five of them!
  • Then they took the plates without N-acetylcysteine and enriched them first with the small amount (2 ml/mg) which resulted in a decreased biofilm and then 10 mg/ml completely eradicating the biofilm structure

As we know in vitro studies aren’t clinically relevant. They are only the first step towards human trials where we can start to draw some more concrete conclusions.

Thankfully the same study continued in it’s exploration of N-acetylcysteine’s biofilm disrupting potentials and ran a clinical trial comparing the effects of NAC pre-antibiotic treatment to antibiotic treatment alone

  • Again patients with 4 failed attempts at treating Helicobacter pylori were assessed via endoscopic examination
  • The bacteria was cultured and assessed for specific antibiotic susceptibility
  • 20 patients received 600 mg once daily of N-acetylcysteine for 1 week.
  • The same group then underwent a specific triple therapy (targeted to their bacterial strain) that included 2 antibiotics and a proton pump inhibitor for 1 week
  • The study compared this group to the control group that skipped the N-acetylcysteine pre-treatment and went straight into the 1 week therapy with the 2 antibiotics (targeted for their strain of Helicobacter pylori) and the proton pump inhibitor
  • 65% of patients receiving the NAC pretreatment cleared the Helicobacter pylori infection compared to only 20% from the group with no NAC pretreatment that cleared the infection

Not surprisingly a whole range of studies have looked into the anti-biofilm activity of NAC and have been summarised in the paper The effect of N-acetylcysteine on biofilms: Implications for the treatment of respiratory tract infections to include

Gram-negative bacteria including

  • Escherichia coli
  • Klebsiella pneumoniae
  • Enterobacter cloacae
  • Proteus spp.
  • Pseudomonas aeruginosa
  • Pseudomonas mendocina
  • Acinetobacter baumannii
  • Prevotella intermedia

Gram-positive bacteria

  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Enterococcus faecalis


  • Candida albicans

Antimicrobial Aspects of NAC

Not only has N-acetylcysteine shown promising anti-biofilm effects on various different microorganisms it is also described in the scientific literature as a

“ non-antibiotic compound that possesses antibacterial properties (8)”

With the growth of a range of bacterial species (Klebsiella pneumoniae, Acinetobacter baumannii, Enterobacter cloacae, Pseudomonas mendocina, Bacillus cereus, and Staphylococcus warneri) being completely inhibited in the presence of NAC (0.4 – 2 mg/ml)

It is still unclear how the antimicrobial aspects of NAC play out with some hypothesising that it inhibits the use of a particular amino acid (cysteine) by the bacteria in question or a particular reaction between the chemistry of NAC and the bacterial cell proteins (8).

Have you tried N Acetyl Cysteine before? What were your experiences? Share below.

References and Resources

  2. Review article: biofilm formation by Helicobacter pylori as a target for eradication of resistant infection
  3. Bacterial biofilms: from the natural environment to infectious diseases.
  4. Treatment of Helicobacter pylori infection 2011.
  5. Review article: the effectiveness of standard triple therapy for Helicobacter pylori has not changed over the last decade, but it is not good enough.
  6. Biofilm demolition and antibiotic treatment to eradicate resistant Helicobacter pylori: a clinical trial.
  7. The effect of N-acetylcysteine on biofilms: Implications for the treatment of respiratory tract infections
  8. Antibacterial effects of N-acetylcysteine against endodontic pathogens. 
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  1. SHOULD NAC be taken on an empty stomach for efficacy ?

    is there a time best suited to take NAC?

    Is it alright to take
    1) NAC
    2) BIOactive carbon
    3) ENZYMES

    all together? or is NAC enough to take the place of enzymes and bioactive carbon?

    1. Hi Melinda, I try my best to stay current with the research coming out. I really like seeing the tri-test coming out of the USA. Hopefully it will be here in Australia soon! Many of the same herbs treat these hydrogen sulfide producers too. Also, the microba test here in Australia helps us to test for many of the less common H2S producers in the large bowel. Not always a direct connection to the small bowel but often an indication.

  2. I am impressed by your knowledge and grateful for this article. Have been very ill for a year and now with alleged heart problems(?) for which I was prescibed anti clotting med for 1 year!!!! 💰💰💰 Have had millions of tests but not one for h pylori (which I am convinced is the culprit!)
    I bought Alex Vasquez’ book on NAC and started adding it to my supplement regimen 10 days ago, and………….my life has already changed 99% for the better. A true miracle!
    Thanks so much for explaining why.

  3. I was prescribed NAC as a treatment in a clinical trial for post concussion syndrome. 600 mg once per day.
    I was skeptical but frustrated by my concussion symptoms. After my nine month mark on the trial, the brain fog lifted and my cognitive function improved to pre-concussive status.
    Although I continued to take 500 mg daily before bed, I was not consistent. But after reading your website I am back on it constantly again as I have SIBO and other gut motility and inflammation issues.
    Very hopeful that NAC will perform its antioxidant job on the rest of my body!

  4. Hello, thanks for the information. I have H2S SIBO and had antibiotic treatment but without anti-biofilm meds… I think that’s why I still have it after 3 years. I’m going to do a microbiome test and after that I believe I’m going to start NAC and after it antibiotics again.
    How much NAC do you recommend taking? I read the dosage of 1000mg twice daily, do you find it appropiate or is it too much? Thank you.

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