Urinary tract infections (UTIs) affect millions of people worldwide – especially women. They are usually caused by bacteria such as Escherichia coli. UTIs are usually treated with antibiotics, but this can lead to resistant bacteria.
The study investigates whether probiotics (i.e. “good” bacteria) and plant-based foods can help prevent infections. These include yogurt, kefir, kombucha, cranberries, garlic and bearberry leaves. They contain healthy bacteria or plant-based active ingredients that work in different ways:
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They strengthen the immune system.
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They prevent harmful germs from adhering to the urinary tract.
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They promote healthy intestinal and vaginal flora.
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Some plants have a diuretic effect, which helps to “flush out” bacteria.
For example, cranberries can prevent E. coli bacteria from settling in the urinary tract, and garlic can have an antibacterial effect against germs such as Candida albicans.
However, despite many positive indications, the authors also emphasize that there are still too few uniform studies on the right dose, duration and effectiveness. The approaches are promising – but more research is needed before clear recommendations can be made.
This narrative systematic review highlights the preventive potential of probiotics and plant-based foods for the prevention of urinary tract infections (UTIs). UTIs are among the most common bacterial infections worldwide, especially in women. The current standard treatment with antibiotics is contributing to the increase in multi-resistant pathogens, which shows an urgent need for alternative or supplementary prevention strategies.
Probiotics as a preventive approach
Probiotics are living microorganisms with health-promoting properties, particularly through their influence on the intestinal and vaginal microbiota. Isolated probiotics such as Lactobacillus crispatus, L. rhamnosus GG or Escherichia coli Nissle 1917 have shown promising effects in studies, for example through:
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Production of antimicrobial substances (e.g. bacteriocins, SCFA)
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Inhibition of pathogen adhesion
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Immunomodulation (e.g. reduction of pro-inflammatory cytokines such as IL-6, TNF-α)
Fermented foods such as kefir, yogurt, miso, sauerkraut, tempeh, natto and kimchi contain natural probiotic cultures and bioactive metabolites with antioxidant and anti-inflammatory effects. These foods improve the diversity of the intestinal flora and could also have a positive effect on urogenital health via the common mucosal immune mechanism. The combination of different bacterial strains appears to have a synergistic effect.
Plant-based foods and extracts
Several herbal active ingredients have been shown to have antimicrobial and diuretic properties:
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Cranberry (Vaccinium macrocarpon): Contains proanthocyanidins that prevent E. coli from attaching to the urinary tract epithelia. Additional mechanisms of action include urine acidification by organic acids and bacteria-inhibiting polyphenols. Studies show significant risk reductions in women with recurrent UTIs, albeit at high doses.
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Garlic (Allium sativum): Allicin and ajoene have antibacterial and antifungal effects, particularly against Candida albicans and E. coli. Studies show anti-inflammatory effects by inhibiting NF-κB and cytokine secretion.
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Bearberry (Arctostaphylos uva-ursi): The substance it contains, arbutin, is metabolized to hydroquinone, which has a bacteriostatic effect. Bearberry also has diuretic and astringent effects.
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Juniper berries (Juniperus communis): The essential oils, especially terpinen-4-ol, promote diuresis and show antimicrobial activity against typical UTI pathogens such as Klebsiella and Proteus.
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Stinging nettle (Urtica dioica): Contains flavonoids and phenolic compounds with diuretic and anti-inflammatory effects. The study situation here is inconsistent, but there are initial indications of antimicrobial effects against uropathogenic germs.
Limitations and need for research
The authors emphasize clear weaknesses in the current study situation: heterogeneous study designs, unclear dosages, a lack of long-term data and a lack of multicentre, randomized studies. There is a lack of standardized extract formulations and statements on safe maximum dosage for many herbal remedies.
Conclusion
The results suggest that probiotics and plant-based foods have a high potential to prevent UTIs – especially in recurrent infections and in populations with impaired kidney function.