10 billion CFU · vegan · gluten-free · 60 caps
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Lactobacillus casei 431 (also called L. paracasei 431 or F19) is a well-characterised probiotic strain with extensive clinical documentation for immune support. Originally isolated from healthy human intestine, it has been studied in multiple RCTs for upper respiratory tract infection (URTI) prevention, immune response to vaccination and general immune competence. It is distinct from L. casei Shirota (Yakult strain) and L. rhamnosus GG.
L. casei 431 enhances innate and adaptive immunity through several mechanisms: it increases natural killer (NK) cell activity, stimulates dendritic cell maturation, enhances antibody responses to vaccines, and modulates cytokine production toward a balanced Th1/Th2 response. A 2015 RCT in 1,104 adults showed that 10 billion CFU/day L. casei 431 significantly reduced URTI duration by 0.8 days and severity scores. A 2012 study showed it enhanced influenza vaccine-specific IgG and secretory IgA responses. It also demonstrates anti-inflammatory effects in high-fat diet models, reducing IL-6 and TNF-α.
Adults seeking immune support during cold and flu season. Those with frequent upper respiratory infections wanting prevention. Individuals receiving influenza vaccination wanting enhanced antibody response. People with stress-related immune depression. Athletes seeking immune support during intense training periods.
Individuals with severe immunosuppression. Those with central venous catheters. People with artificial heart valves. Not for premature infants. Side effects: Generally well-tolerated. Mild GI adjustment in first 1–2 weeks. No serious adverse events in large RCTs (n=1,104). As with all probiotics, immunocompromised individuals should consult a physician.
A plain-English read of the literature behind this supplement. Not a clinical recommendation.
Key citations: PMID 25926507 (URTI RCT, n=1,104), PMID 21899798 (vaccine response enhancement), PMID 26059375 (anti-inflammatory in obesity), PMID 21395664 (immunomodulatory against Candida)
SacredBod's longer take on Lactobacillus Casei 431 — context the structured blocks above don't capture.
Lactobacillus casei 431 (also called L. paracasei 431 or F19) is a well-characterised probiotic strain with extensive clinical documentation for immune support. Originally isolated from healthy human intestine, it has been studied in multiple RCTs for upper respiratory tract infection (URTI) prevention, immune response to vaccination and general immune competence. It is distinct from L. casei Shirota (Yakult strain) and L. rhamnosus GG.
L. casei 431 enhances innate and adaptive immunity through several mechanisms: it increases natural killer (NK) cell activity, stimulates dendritic cell maturation, enhances antibody responses to vaccines, and modulates cytokine production toward a balanced Th1/Th2 response. A 2015 RCT in 1,104 adults showed that 10 billion CFU/day L. casei 431 significantly reduced URTI duration by 0.8 days and severity scores. A 2012 study showed it enhanced influenza vaccine-specific IgG and secretory IgA responses. It also demonstrates anti-inflammatory effects in high-fat diet models, reducing IL-6 and TNF-α.
Adults seeking immune support during cold and flu season. Those with frequent upper respiratory infections wanting prevention. Individuals receiving influenza vaccination wanting enhanced antibody response. People with stress-related immune depression. Athletes seeking immune support during intense training periods.
Typical dose: 10 billion CFU per day
Form: capsules (60 count)
Best time: morning
With food: with-food
Expected onset: 2–4 weeks for immune priming; 4–8 weeks for infection reduction
Cycling: No cycling required. Continuous daily use supported by RCT data.
Known side effects: Generally well-tolerated. Mild GI adjustment in first 1–2 weeks. No serious adverse events in large RCTs (n=1,104). As with all probiotics, immunocompromised individuals should consult a physician.
Who should avoid: Individuals with severe immunosuppression. Those with central venous catheters. People with artificial heart valves. Not for premature infants.
Avoid combining with: Antibiotics (take 2 hours apart), Immunosuppressants, Live vaccines (theoretical interaction — consult physician)
Lactobacillus Casei 431 is available on Amazon India with varying brand quality. When selecting a probiotic, verify CFU count at expiry (not just at manufacture), strain specificity and refrigeration requirements. Indian brand preferences include Tata 1mg, ZEROHARM, Carbamide Forte, HealthKart, Jarrow Formulas, Now Foods, and Meibotan. Prices vary significantly; compare cost-per-CFU rather than capsule count alone.
Schedule status in India: Not a Schedule H drug; available as dietary supplement.
Key citations: PMID 25926507 (URTI RCT, n=1,104), PMID 21899798 (vaccine response enhancement), PMID 26059375 (anti-inflammatory in obesity), PMID 21395664 (immunomodulatory against Candida)
Evidence grade: B — n=1,104 in largest URTI RCT; multiple immune mechanism studies
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