Helicobacter pylori (H. pylori) infection affects approximately 20–30% of the UK population and is the primary cause of peptic ulcer disease. Whilst standard antibiotic-based eradication therapy remains the cornerstone of treatment, rising antibiotic resistance and treatment side effects have prompted interest in adjunctive approaches. Probiotics—live microorganisms that confer health benefits—are increasingly studied alongside conventional H. pylori therapy. Evidence suggests certain probiotic strains may modestly improve eradication rates and significantly reduce antibiotic-associated side effects, particularly diarrhoea. However, probiotics are not a replacement for standard treatment, and NICE guidance does not currently recommend their routine use. This article examines the evidence for probiotics in H. pylori management, including mechanisms of action, specific strains studied, and important safety considerations.

What Is H. pylori and Why Does It Matter?

Helicobacter pylori (H. pylori) is a spiral-shaped bacterium that colonises the stomach lining, affecting approximately 20-30% of the UK population, with higher rates in older adults and certain ethnic groups. This microorganism has evolved unique mechanisms to survive in the acidic gastric environment, producing urease enzyme that neutralises stomach acid and allows it to burrow into the protective mucus layer.

Whilst many people with H. pylori remain asymptomatic throughout their lives, the infection is clinically significant because it represents the primary cause of peptic ulcer disease, accounting for roughly 90% of duodenal ulcers and 70% of gastric ulcers. The bacterium triggers chronic inflammation of the stomach lining (gastritis), which can progress over decades to more serious conditions. The International Agency for Research on Cancer (IARC) classifies H. pylori as a Group 1 carcinogen due to its established link with gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma.

NICE guidance recommends testing for H. pylori in patients with dyspepsia and in those with endoscopically confirmed peptic ulcer disease. The British Society of Gastroenterology (BSG) suggests considering H. pylori testing in patients with unexplained iron deficiency anaemia. Diagnosis typically involves non-invasive methods such as the urea breath test or stool antigen test. Importantly, patients should stop taking proton pump inhibitors (PPIs) for 2 weeks and antibiotics or bismuth for 4 weeks before these tests to avoid false-negative results. Serology is generally not recommended for diagnosing active infection in UK practice. Endoscopic biopsy with rapid urease testing or histology may be performed when endoscopy is clinically indicated.

Eradication of H. pylori significantly reduces ulcer recurrence rates and may decrease gastric cancer risk in certain populations. However, standard antibiotic-based eradication therapy faces challenges including rising antibiotic resistance rates, treatment side effects, and incomplete eradication in 10–20% of cases. These limitations have prompted interest in adjunctive therapies, including probiotics, to improve treatment outcomes and reduce adverse effects.

How Probiotics May Help With H. pylori Infection

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. In the context of H. pylori infection, probiotics may exert beneficial effects through several proposed mechanisms, though it is important to note that probiotics are not a replacement for standard antibiotic therapy.

Direct antimicrobial activity represents one potential mechanism. Certain probiotic strains produce antimicrobial substances including organic acids (particularly lactic acid), hydrogen peroxide, and bacteriocins that may inhibit H. pylori growth or reduce its ability to adhere to gastric epithelial cells. Laboratory studies have demonstrated that some Lactobacillus and Bifidobacterium species can suppress H. pylori in vitro, though translating these findings to clinical outcomes remains complex.

Competitive exclusion is another proposed mechanism whereby probiotic bacteria compete with H. pylori for adhesion sites on the gastric mucosa and for nutrients, potentially reducing H. pylori colonisation density. Some probiotic strains may also produce biosurfactants that interfere with H. pylori's ability to attach to stomach cells.

Immunomodulation represents a third mechanism of action. Probiotics can modulate both innate and adaptive immune responses, potentially enhancing the host's ability to control H. pylori infection. This includes stimulating secretory IgA production, modulating inflammatory cytokine profiles, and enhancing epithelial barrier function.

Crucially, when probiotics are used alongside standard eradication therapy, they may help reduce antibiotic-associated side effects, particularly diarrhoea. The evidence for reduction of other side effects such as nausea and taste disturbances is less consistent. By maintaining a healthier gut microbiome during antibiotic treatment, probiotics may improve treatment tolerability and adherence, indirectly supporting successful eradication.

It's important to understand that these effects are strain-specific and dose-dependent, with clinical benefits varying considerably between different probiotic products and treatment regimens.

Evidence for Probiotics Alongside Standard H. pylori Treatment

The evidence base for probiotics as an adjunct to standard H. pylori eradication therapy has grown substantially over the past two decades, with numerous randomised controlled trials and systematic reviews examining their role. Standard first-line treatment in the UK typically consists of a proton pump inhibitor (PPI) with two antibiotics for 7 days. According to NICE antimicrobial prescribing guidance, antibiotic selection should consider previous exposure: clarithromycin should be avoided if there has been prior macrolide use, and metronidazole should be avoided with prior metronidazole exposure. Bismuth quadruple therapy is an alternative first-line option, particularly in areas with high clarithromycin resistance.

A 2019 Cochrane systematic review analysed data from multiple trials and found that adding probiotics to standard eradication therapy may modestly improve eradication rates and significantly reduce treatment-related side effects. The review suggested that probiotics might increase eradication success by approximately 5–10 percentage points, though results varied considerably between studies depending on probiotic strain, dose, and treatment regimen.

Meta-analyses have consistently demonstrated that probiotics reduce the incidence of antibiotic-associated adverse effects, particularly diarrhoea, which affects 20–30% of patients receiving standard therapy. Some analyses have found that probiotics reduced overall side effects by approximately 40%, though this varies by probiotic strain and study methodology. Reducing side effects may improve treatment adherence—a critical factor given that incomplete courses contribute to treatment failure and antibiotic resistance.

However, important caveats exist. The quality of evidence varies, with significant heterogeneity between studies regarding probiotic species, strains, doses, duration of supplementation, and outcome measures. Not all probiotic preparations show benefit, and there is no official link established between all probiotic products and improved H. pylori outcomes.

NICE guidance does not currently recommend routine use of probiotics for H. pylori eradication. It's worth noting that most probiotics available in the UK are regulated as food supplements rather than medicines. While some healthcare professionals may discuss probiotics on a case-by-case basis, particularly for patients at higher risk of antibiotic-associated complications, this represents practice outside of formal NICE recommendations.

Which Probiotic Strains Are Most Studied for H. pylori?

Not all probiotics are equivalent, and the effects observed with one strain cannot be extrapolated to others. Research has focused on specific strains with demonstrated survival in the acidic gastric environment and potential anti-H. pylori activity.

Lactobacillus species represent the most extensively studied group:

• Lactobacillus reuteri DSM 17938 has shown promising results in several trials, with demonstrated ability to co-aggregate with H. pylori and produce reuterin, a broad-spectrum antimicrobial compound

• Lactobacillus acidophilus has been studied both alone and in combination formulations, with some evidence for reducing H. pylori load

• Lactobacillus casei and Lactobacillus rhamnosus GG (ATCC 53103) have demonstrated benefits in reducing treatment-related side effects in multiple trials

Saccharomyces boulardii CNCM I-745, a probiotic yeast rather than a bacterium, has robust evidence for preventing antibiotic-associated diarrhoea and has been specifically studied in H. pylori eradication protocols. Its effects on H. pylori eradication rates are less consistent. Its resistance to antibiotics allows it to be taken concurrently with eradication therapy without being destroyed by the antibiotics themselves.

Bifidobacterium species, including B. bifidum and B. lactis, have shown benefits in some studies, particularly when used in multi-strain formulations.

Multi-strain preparations combining several Lactobacillus and Bifidobacterium species have been investigated on the premise that different strains may exert complementary effects. Some evidence suggests these combinations may be more effective than single strains, though this remains an area requiring further research.

When considering probiotic supplementation, patients should look for products specifying the exact strain designation (not just species), providing adequate colony-forming units (with effective doses varying by strain and product), and demonstrating stability through appropriate storage. It's important to note that most probiotics in the UK are regulated as food supplements, not medicines, and cannot make medicinal claims. Healthcare professionals can help guide patients toward evidence-based selections rather than relying on marketing claims.

Safety and Considerations When Using Probiotics for H. pylori

Probiotics are generally considered safe for the majority of individuals, with an established history of consumption in fermented foods and as dietary supplements. However, several important considerations apply when using probiotics in the context of H. pylori infection.

Safety profile: For immunocompetent individuals, probiotics typically cause only mild, transient side effects such as bloating or flatulence during the first few days of use. Serious adverse events are rare. However, caution is warranted in immunocompromised patients, those with central venous catheters, patients with severe acute pancreatitis, or individuals with damaged intestinal barriers, as rare cases of probiotic-related bacteraemia or fungaemia have been reported in these vulnerable populations. People who are pregnant or breastfeeding should consult a healthcare professional before starting probiotics or H. pylori eradication therapy.

Timing and duration: When used alongside H. pylori eradication therapy, probiotics are typically started at the beginning of antibiotic treatment and continued for 2–4 weeks. Some protocols extend probiotic use beyond antibiotic completion to support microbiome recovery. As a pragmatic approach, patients may take probiotics at least 2 hours apart from antibiotics to optimise probiotic survival, though this advice varies by product and S. boulardii can be taken concurrently with antibiotics.

Important limitations: Patients must understand that probiotics are not a substitute for standard eradication therapy. There is insufficient evidence to support probiotics as monotherapy for H. pylori infection. Anyone with confirmed H. pylori requiring treatment should receive appropriate antibiotic-based eradication therapy as recommended by NICE guidelines.

When to contact your GP: Patients should seek medical advice if they experience severe or persistent abdominal pain, vomiting, blood in stools, unintentional weight loss, dysphagia (difficulty swallowing), or symptoms of anaemia (fatigue, pallor, breathlessness). These may indicate complications requiring urgent assessment. Additionally, if symptoms persist after completing eradication therapy, follow-up is needed. Test-of-cure is particularly recommended for patients with peptic ulcer disease, MALT lymphoma, gastric atrophy/intestinal metaplasia, after endoscopic resection of early gastric cancer, or if symptoms persist. Testing should be performed at least 4 weeks after completing antibiotics and 2 weeks after stopping PPIs.

Product selection: The UK probiotic market is primarily regulated as food supplements, not medicines. Product quality varies considerably. Patients should choose products from reputable manufacturers that specify strain identity, guarantee viable organisms through expiry, and provide evidence of appropriate storage conditions.

Suspected adverse reactions to medicines (including antibiotics and PPIs) can be reported through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk or the Yellow Card app).

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