H. pylori

A bacterium that reshapes the whole gut

H. pylori is a bacterium that infects the stomach lining, and it's one of the most common infections in the world, carried by an estimated 44% of people globally. It's the main known cause of chronic gastritis and peptic ulcers, and a significant risk factor for stomach cancer. Its effects reach well beyond the stomach itself.

A shotgun metagenomic study of 313 people found 58 gut bacterial species that reliably differed between people with and without H. pylori, a pattern strong enough that a classifier built from these species could detect infection with high accuracy. The same study found that people with H. pylori had measurably lower vitamin B12 levels, both in their gut bacteria's B12 production and in their blood, linking the infection to a nutrient deficiency far outside the stomach.

Source: PMC, Alterations in the human gut microbiome associated with Helicobacter pylori infection

Not everyone with the infection gets sick

Most people carrying H. pylori never develop symptoms, and researchers have long wondered why. A study of 375 people in India found a possible answer in the gut: people infected with H. pylori had lower levels of two beneficial bacteria groups, Bifidobacterium and Bacteroides, and higher levels of others, Dialister and Prevotella, compared with uninfected people. Low Bifidobacterium specifically has been linked to a higher risk of H. pylori-related ulcers and stomach cancer, suggesting the surrounding gut bacteria may help determine who develops serious disease and who doesn't.

Source: PMC, Low Bifidobacterium Abundance in the Lower Gut Microbiota Is Associated With Helicobacter pylori-Related Gastric Ulcer and Gastric Cancer

One gene decides who is most at risk

Only about 1% of people infected with H. pylori ever develop gastric cancer. Researchers have found part of the explanation in the bacterium's own genes. Some H. pylori strains carry a gene called CagA. It makes a protein that gets injected directly into stomach cells, where it disrupts their normal signalling and can push them toward becoming cancerous.

In a study in Korea, researchers compared 100 people with gastric cancer to 400 people without it. Among those infected with H. pylori, people carrying the CagA-positive strain were far more likely to have gastric cancer, over three times more likely, than those with a CagA-negative strain. This is one reason H. pylori infection alone does not predict cancer risk well. Which strain a person carries matters just as much as whether they are infected at all.

Source: CagA-producing Helicobacter pylori and increased risk of gastric cancer: a nested case-control study in Korea

Adding gut bacteria to treatment improves it

Standard H. pylori treatment does not always work. A large meta-analysis pooling 96 clinical trials and 13,829 patients found that adding a probiotic to standard antibiotic treatment raised the eradication rate from 62.43% to 78.75%. Patients taking probiotics also reported fewer side effects, including less nausea, diarrhoea, and abdominal pain. One specific bacterium, Bifidobacterium longum, stood out as the most effective probiotic strain tested for helping treatment succeed.

Source: Efficacy of probiotics regimens for Helicobacter pylori eradication: a systematic review, pairwise, and network meta-analysis of randomized controlled trials

What this means for you

H. pylori is diagnosed with a breath, stool, or blood test, and treated with a course of antibiotics plus acid-reducing medication when a doctor confirms infection and symptoms. Persistent stomach pain, unexplained weight loss, or dark stools need medical assessment. Alongside proper treatment, a varied, plant-rich diet supports the same beneficial bacteria, like Bifidobacterium, that the research above links to better outcomes. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.