What the evidence says. Several controlled trials; effects real but modest or context-dependent.
What is Lactobacillus paracasei?
Lactobacillus paracasei (Lacticaseibacillus paracasei (Lpc-37, CNCM I-1518)) is a probiotic strain used for reduces the incidence of common infectious diseases (colds, gi infections) as the fermented-dairy strain cncm i-1518 — ~19% lower odds of ≥1 infection. NutriDex grades the human evidence as Moderate. Lacticaseibacillus paracasei is not one product but several well-characterized strains with divergent evidence. The strongest data is for CNCM I-1518 (the Actimel/DanActive fermented dairy strain): a 2020 meta-analysis of 9 RCTs found it modestly reduced the odds of catching common infections (OR 0.81). Strain Lpc-37 has been tested for stress with mixed results — a benefit on perceived stress in healthy adults (Sisu study) but no effect on exam anxiety in students (ChillEx), with an exploratory sleep-disturbance benefit. LP-33 improved quality of life in grass-pollen allergic rhinitis (425-subject GA2LEN trial), mainly via ocular rather than nasal symptoms. Benefits do not transfer between strains.
Purported Benefits
✓Reduces the incidence of common infectious diseases (colds, GI infections) as the fermented-dairy strain CNCM I-1518 — ~19% lower odds of ≥1 infection
✓Lowers perceived stress in healthy chronically-stressed adults (Lpc-37), with greater effect in women
✓Improves quality of life in grass-pollen allergic rhinitis on top of antihistamine (LP-33), chiefly ocular symptoms
✓May normalize evening cortisol and reduce stress-related sleep disturbance in selected populations (Lpc-37)
✓Generally well tolerated as an adjunct in immune and allergy support
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
Strain- and indication-dependent. Immune support: one ~100 mL fermented dairy drink/day delivering ~10^10 CFU CNCM I-1518. Stress (Lpc-37): ~1.5–1.75 × 10^10 CFU/day for 5–10 weeks. Allergic rhinitis (LP-33): ~10^9 CFU/day. Taken daily, often with a meal.
Well tolerated across trials with no serious adverse events attributable to the probiotic, including in healthy adults and students. As with all live probiotics, avoid in critically ill, severely immunocompromised, or central-venous-catheter patients, where rare bacteremia/translocation has been reported for Lactobacillus species. Fermented dairy products are not suitable for severe milk-protein allergy. Effects are strain-specific — do not assume one strain's benefit applies to another product. Educational only — always check with your doctor or pharmacist before combining Lactobacillus paracasei with any medicine.
Lactobacillus paracasei is most often taken for Reduces the incidence of common infectious diseases (colds, GI infections) as the fermented-dairy strain CNCM I-1518 — ~19% lower odds of ≥1 infection, Lowers perceived stress in healthy chronically-stressed adults (Lpc-37), with greater effect in women, Improves quality of life in grass-pollen allergic rhinitis on top of antihistamine (LP-33), chiefly ocular symptoms, May normalize evening cortisol and reduce stress-related sleep disturbance in selected populations (Lpc-37). A versatile probiotic species whose effects are tightly strain-specific — immune support (CNCM I-1518), stress (Lpc-37), and allergy (LP-33)
Does Lactobacillus paracasei work — what does the evidence say?
Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Lacticaseibacillus paracasei is not one product but several well-characterized strains with divergent evidence. The strongest data is for CNCM I-1518 (the Actimel/DanActive fermented dairy strain): a 2020 meta-analysis of 9 RCTs found it modestly reduced the odds of catching common infections (OR 0.81). Strain Lpc-37 has been tested for stress with mixed results — a benefit on perceived stress in healthy adults (Sisu study) but no effect on exam anxiety in students (ChillEx), with an exploratory sleep-disturbance benefit. LP-33 improved quality of life in grass-pollen allergic rhinitis (425-subject GA2LEN trial), mainly via ocular rather than nasal symptoms. Benefits do not transfer between strains.
What is the typical dose of Lactobacillus paracasei?
Strain- and indication-dependent. Immune support: one ~100 mL fermented dairy drink/day delivering ~10^10 CFU CNCM I-1518. Stress (Lpc-37): ~1.5–1.75 × 10^10 CFU/day for 5–10 weeks. Allergic rhinitis (LP-33): ~10^9 CFU/day. Taken daily, often with a meal.
Is Lactobacillus paracasei safe? Any cautions or side effects?
Well tolerated across trials with no serious adverse events attributable to the probiotic, including in healthy adults and students. As with all live probiotics, avoid in critically ill, severely immunocompromised, or central-venous-catheter patients, where rare bacteremia/translocation has been reported for Lactobacillus species. Fermented dairy products are not suitable for severe milk-protein allergy. Effects are strain-specific — do not assume one strain's benefit applies to another product.
How many studies support Lactobacillus paracasei?
NutriDex cites 9 sources for Lactobacillus paracasei, graded "Moderate".
Cite this page
APA
Peh, D. (2026). Lactobacillus paracasei (Lacticaseibacillus paracasei (Lpc-37, CNCM I-1518)): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/l-paracasei
BibTeX
@misc{nutridex_l_paracasei,
author = {Peh, Daryl},
title = {Lactobacillus paracasei (Lacticaseibacillus paracasei (Lpc-37, CNCM I-1518)): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/l-paracasei},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.