Helicobacter pylori is the most common bacterial infection worldwide, colonising the gastrointestinal tract of more than 50% of the global population.¹ 

A highly adapted, spiral shaped, gram negative bacteria,² H. pylori can persist in the stomach of an infected person for their entire life and, in about 70% of cases, be completely asymptomatic.^1,3 Unfortunately this persistence triggers gastric inflammation and damage to the mucosal barrier which, in turn, leads to the development of various gastric disorders ranging from mild discomfort to more serious conditions such as peptic and duodenal ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric adenocarcinoma (the third most common cause of cancer-related deaths worldwide).^4-6

Although the majority of the human population is colonised by H. pylori, only about 10–20% are likely to develop peptic ulcer, and only 1–2% are at risk for gastric cancer.³ Many factors are known to influence an individual’s risk of gastrointestinal disease, with most emphasis to date focusing on host genetics, bacterial virulence factors, and environmental factors, particularly diet (see figure 1). However, a potentially significant determinant of the outcome of H. pylori infection that is gaining traction is the composition of the host gut microbiota and the use of probiotics.^7,8

Figure 1. Risk factors for H. pylori-associated disease.⁷

Classical first-line treatment of patients diagnosed with H. pylori infection involves the use of triple therapy (which consists of concomitant prescription of two antibiotics and a proton pump inhibitor). Quadruple therapy (i.e. concomitant prescription of three antibiotics and a proton-pump inhibitor) remains the best second-choice treatment. However, H. pylori eradication rates following this standard regime are generally poor due to antimicrobial resistance and patient non-compliance.^4,9 

Influence of H. pylori on the gut microbiota

The gut microbiota plays an integral role in numerous physiological and metabolic processes, and the delicate balance within which our microbiota exist determines states of health or disease.^10,11 The introduction of H. pylori to the stomach may lead to disease indirectly by disrupting this balance of beneficial organisms.¹

Recent studies have revealed significant differences between the microbiota of individuals with and without H. pylori infection.¹² Overall, H. pylori-negative individuals harbor a microbiota that is more complex and highly diverse compared to H. pylori-positive individuals (see Figure 2). In H. pylori-negative individuals, the most abundant phyla are typically Firmicutes, Actinobacteria and Bacteroidetes. Following infection with H. pylori, Proteobacteria (and specifically H. pylori) dominate the gastric microbiota.¹  

Figure 2. Alterations in the gastric microbiota following H. pylori infection.

It is suggested that Proteobacteria (such as H. pylori) may represent a “microbial signature” of disease, as they are often overrepresented in several intestinal and extra-intestinal diseases, mostly with an inflammatory phenotype. Examples of disorders in which Proteobacteria are implicated include IBD, obesity, diabetes, asthma, COPD and NASH/NAFL.¹³

Influence of probiotics on H. pylori

Probiotics are emerging as an effective adjunct and, at times, alternative to antibiotics in the treatment of gastrointestinal infections such as H. pylori. Mechanisms via which probiotic bacteria can inhibit H. pylori include both immunological and non-immunological means (see Figure 3).¹⁴

Figure 3. Immunological and non-immunological mechanisms of probiotics in host defence.⁸

Lactobacillus and Bifidobacterium are the two most common species used as probiotics and have been extensively investigated for their beneficial effects on the host.¹⁵ The various mechanisms of action via which probiotics may impact H. pylori pathogenicity include:

• Competition for adhesion.¹⁵
• Competition for nutrients.⁸
• Production of anti-microbial substances such as short-chain fatty acids, bacteriocins, and urease inhibitors.^3,16,17
• Restoration and protection of the mucosal barrier that make the host environment less hospitable to infection.^15,16,18
• Altering host immune response by shifting the balance of Th1, Th17, and regulatory T cell activity,⁷ and increasing IgA and immunoglobulin secreting cells.⁸

The need for additional strategies

Although great advances have been made in understanding the complex interplay between the gastric microbiota, probiotics and H. pylori in the development of gastric inflammation and disease, herbal medicine can play a fundamental part of any H. pylori treatment protocol. An increasing number of studies suggest that H. pylori infection can be suppressed through the use of medicinal plants, with the benefit of less adverse side effects than conventional treatments.^19,20

Key herbs and phytochemicals that have shown activity against H. pylori include garlic²¹, thyme²², cinnamon²³, turmeric^24,25, golden seal²⁶, green tea²⁷, ginger²⁸, cranberry²⁹, broccoli sprout extract (isothiocyanate sulforaphane)³⁰, olive leaf extract²⁸, and deglycyrrhizinated licorice root (DGL).³¹

In addition to their anti-microbial activity, medicinal herbs also impart broader benefits via their antioxidant, anti-inflammatory, immunomodulatory and gastro-protective properties⁴ allowing us, as natural healthcare practitioners, to do what we do best - and that is to treat the person and not just the disease.

Still so much to learn

The gastrointestinal tract is a complex and dynamic network that includes interactions between intestinal mucosal cells, the immune system, food particles, the commensal microbiota and pathogenic bacteria. By gaining a more in-depth understanding of the intricate relationship between gut bacteria and human health, we will be better placed to develop new strategies in the treatment and management of a wide variety of human diseases.

References

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