Cats are among the most popular pets worldwide – yet millions of people experience allergic reactions to their presence. Symptoms range from mild sneezing to severe shortness of breath. While conventional treatment methods often aim to suppress symptoms, a new therapeutic approach is increasingly gaining attention: the modulation of the immune system through probiotics. Two bacterial strains are particularly interesting in this regard: Lactobacillus paracasei LP-33 and GMNL-133 . In this article, we examine the mechanisms of action, research, application, and potential of probiotics to support cat allergies.
Allergy to cats – a look at the immune system
A cat allergy is an overreaction of the immune system to harmless proteins—particularly the protein Fel d 1 , which is found in the cat's saliva, dander, and sebaceous glands. In allergic humans, the immune system mistakenly recognizes this protein as a threat. The result is excessive production of immunoglobulin E (IgE), which triggers inflammatory reactions such as a runny nose, itchy eyes, or shortness of breath.
The severity of the reaction depends not only on the amount of allergen, but also on the affected person's immune balance. This is where probiotics come in: They can steer the immune system toward tolerance.
What are probiotics and how do they work?
Probiotics are live microorganisms – usually lactic acid bacteria – that, when consumed in sufficient quantities, provide health benefits to the host. The best-known genera are Lactobacillus and Bifidobacterium . They exert their effects primarily through the intestine, which is considered the central hub of the immune system: About 70% of all immune cells are located there.
Probiotics can modulate allergic reactions in several ways:
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Strengthening the intestinal barrier: An intact intestinal mucosa prevents allergens from entering the bloodstream.
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Promoting regulatory T cells: These immune cells are crucial for tolerance to harmless substances.
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Reduction of pro-inflammatory cytokines: Probiotics can inhibit pro-inflammatory messengers and simultaneously enhance anti-inflammatory signals.
The result is that the allergic reaction is reduced and the immune system reacts less sensitively to the cat allergen.
Studies on Lactobacillus paracasei LP-33
The strain Lactobacillus paracasei LP-33 is one of the best-studied probiotics for allergic rhinitis – a runny nose caused by allergies, which also frequently occurs in cat allergies.
In a placebo-controlled, double-blind study from Taiwan, 425 people with seasonal allergic rhinitis took LP-33 for five weeks. The results: Both nasal symptoms and quality of life improved significantly compared to the placebo group. Itching and watery eyes also decreased. The authors conclude that LP-33 reduces inflammatory processes and modulates the mucosal response.
A subsequent meta-analysis confirmed the benefit in allergic rhinitis, noting that people allergic to house dust and pet hair in particular could benefit from LP-33. Although no direct study in cat allergy sufferers exists, these data suggest that the effect may also be relevant in cases of Fel d 1 sensitization.
Lactobacillus paracasei GMNL-133 – a beacon of hope
A relatively new but promising strain is Lactobacillus paracasei GMNL-133 (also a Lactobacillus paracasei strain). In animal models, GMNL-133 has been shown to significantly attenuate allergic reactions. The mice in the study showed fewer IgE antibodies and reduced histamine release—two key markers of allergic processes.
In a pilot study with people suffering from house dust and pet allergies, capsules containing GMNL-133 were administered for 12 weeks. Participants reported a noticeable reduction in nasal symptoms and improved sleep quality. These are very promising results.
Although the data available is still limited, the results obtained so far indicate a strong immunomodulatory potential of this strain – especially in the context of chronic or difficult-to-treat allergies such as cat allergy.
How long should you take probiotics for cat allergies?
Probiotics do not work immediately. Their effect develops gradually, as they influence the immune balance over time. For a stable benefit, a duration of use of at least 8 to 12 weeks is recommended , ideally prior to expected allergen exposure (e.g., when visiting a cat home or adopting a cat).
When taken over a long period of time—for example, over several months—probiotics can help sustainably reduce allergy symptoms. Regularity is crucial: Taking them daily, preferably on an empty stomach or before a meal, improves absorption and effectiveness.
Safety and tolerability
Both LP-33 and GMNL-133 are considered safe and well-tolerated. No side effects were observed in clinical trials. Consultation with a physician is recommended for immunocompromised individuals, as is the case if taking immunosuppressive medications.
Conclusion: Probiotics as supportive therapy for cat allergy
The question "Do probiotics help with cat allergies?" can now be answered with a cautious but well-founded yes. Studies and clinical observations show that the strains Lactobacillus paracasei LP-33 and GMNL-133, in particular , have shown great potential to alleviate allergic reactions. They act on the immune system via the gut, strengthen tolerance to allergens, and reduce the tendency to inflammation.
For allergy sufferers who don't want to avoid cat contact despite symptoms, probiotics can be a valuable component in individual allergy management—complementing hygiene measures, air purification, and, if necessary, medication. Consistent and long-term use is important.
Whether to prepare for life with a cat or to alleviate existing complaints: probiotics could pave the way for a harmonious coexistence between humans and animals – even with sensitive immune systems.
