Lacticaseibacillus paracasei

Lacticaseibacillus paracasei (formerly Lactobacillus paracasei) is a probiotic species found naturally in the human gut, fermented foods, and dairy products. Reclassified in 2020 from Lactobacillus to the new genus Lacticaseibacillus. NO GRADED OUTCOMES - research is strain-specific and scattered. Various strains have been studied for immune function, allergies, oral health, and gut health. Effects are highly strain-dependent - L. paracasei is a species, and different strains (like L. paracasei Lpc-37 or L. paracasei Shirota) may have different effects. Generally safe as a probiotic.

Quick Answer

What it is

Lacticaseibacillus paracasei (formerly Lactobacillus paracasei) is a probiotic species found naturally in the human gut, fermented foods, and dairy products. Reclassified in 2020 from Lactobacillus to the new genus Lacticaseibacillus.

Key findings

  • Grade C: Gut Microbiota Composition
  • Grade C: Inflammatory Markers
  • Grade D: Depressive and Cognitive Symptoms

Safety

  • No adverse events reported.
ℹ️ Quick Facts: Lacticaseibacillus paracasei

Quick Facts: Lacticaseibacillus paracasei

  • Best Evidence:Grade D
  • Conditions Studied:2
  • Research Outcomes:8
  • Key Effect:Asthma
Outcomes by grade:
A0
B0
C2
D6
2 conditions · 8 outcomes

Detailed Outcomes

|
C
Gut Microbiota Composition
An RCT in 82 patients with depression found L. paracasei strain Shirota significantly increased beneficial bacteria (Adlercreutzia, Megasphaera, Veillonella) and decreased bacteria associated with mental illness. Multiple preclinical studies and a review of kefir isolates confirm bifidogenic effects, pathogen reduction, and short-chain fatty acid elevation across various L. paracasei strains.
smallImproves
C
Inflammatory Markers
A double-blind RCT (n=82) found significantly lower IL-6 levels in the L. paracasei Shirota group versus placebo (p<0.05). Animal studies consistently show reduced IL-1β, IL-6, TNF-α, and NF-κB activation in colitis, neuroinflammation, and airway inflammation models across multiple strains (NK112, K47, encapsulated formulations).
smallImproves
D
Depressive and Cognitive Symptoms
In mice, L. paracasei NK112 significantly alleviated E. coli-induced anxiety, depression, and memory impairment, while increasing hippocampal BDNF and reducing neuroinflammatory markers. A human RCT (n=82) of strain Shirota in depressed patients with constipation showed depression scores decreased in both groups but no significant between-group difference, suggesting the effect may not be specific to the probiotic.
smallImproves
D
Intestinal Inflammation (Colitis)
In a DSS-induced colitis mouse model, encapsulated L. paracasei biofilm-like microcolonies decreased colonic mucosal injuries and reduced inflammation severity, with lower TNF-α, IL-1β, and IL-17A expression. A review of kefir-derived L. paracasei strains confirms anti-inflammatory and pathogen-adhesion-reducing properties in cell culture models. No human colitis trials identified.
moderateImproves
D
Uric Acid Levels
In vitro and mouse studies of L. paracasei M2a demonstrated ~47% uric acid degradation efficiency. In hyperuricemic mice, supplementation significantly improved liver and kidney biomarkers (ALT, AST, BUN, creatinine; p<0.05), reduced inflammatory infiltration, and increased beneficial gut bacteria. No human clinical trials available.
moderateImproves
D
Constipation Symptoms
A 9-week double-blind RCT (n=82) of L. paracasei strain Shirota in depressed patients with constipation found no significant between-group difference in total constipation symptom scores. Secondary outcomes showed improvements in rectal tearing/bleeding and stool characteristics favoring the probiotic group, but these did not meet the primary endpoint threshold.
smallImproves
D
Allergic Airway Inflammation
In an OVA-sensitized mouse model, heat-inactivated L. paracasei K47 significantly reduced total IgE, OVA-specific IgE, and OVA-specific IgG1, ameliorated airway hyperresponsiveness, suppressed inflammatory cell accumulation in bronchoalveolar lavage fluid, and rebalanced Th1/Th2 cytokine profiles. No human data available.
moderateImproves
D
Abdominal Fat
A 12-week double-blind RCT (n=80, BMI 23-30) of heat-killed L. paracasei K71 did not reach significance on the primary per-protocol analysis for fat reduction. However, subgroup analysis in participants with stable lifestyles showed significant decreases in subcutaneous fat area, visceral fat volume, body fat percentage, and hip circumference. No adverse events reported.
smallImproves

Evidence by Condition

Best grade per condition (each condition may have multiple outcomes)

Research Citations (10)

The Effect of Heat-Killed Lacticaseibacillus paracasei K71 on Abdominal Fat Reduction: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Comparative Trial
(2025)
PMID: 41183976
Safety Evaluation of Human-Derived Uric Acid Degrading Lacticaseibacillus paracasei M2a and Its Impact on Gut Microbiota
(2025)
PMID: 40316867
Effect of a Lactobacilli-Based Direct-Fed Microbial Product on Gut Microbiota and Gastrointestinal Morphological Changes
(2024)
PMID: 38473078
Supplementation with heat-inactivated Lacticaseibacillus paracasei K47 ameliorates allergic asthma in mice by regulating the Th1/Th2 balance
(2022)
PMID: 35067214
Effects of Fermented Milk Containing Lacticaseibacillus paracasei Strain Shirota on Constipation in Patients with Depression: A Randomized, Double-Blind, Placebo-Controlled Trial
(2021)
PMID: 34209804
Lacticaseibacillus paracasei NK112 mitigates Escherichia coli-induced depression and cognitive impairment in mice by regulating IL-6 expression and gut microbiota
(2021)
PMID: 34511050
Health-Promoting Properties of Lacticaseibacillus paracasei: A Focus on Kefir Isolates and Exopolysaccharide-Producing Strains
(2021)
PMID: 34681288
Intestinal release of biofilm-like microcolonies encased in calcium-pectinate beads increases probiotic properties of Lacticaseibacillus paracasei
(2020)
PMID: 33116127
New Bacteriocins from Lacticaseibacillus paracasei CNCM I-5369 Adsorbed on Alginate Nanoparticles Are Very Active against Escherichia coli
(2020)
PMID: 33212803
Resveratrol Favors Adhesion and Biofilm Formation of Lacticaseibacillus paracasei subsp. paracasei Strain ATCC334
(2020)
PMID: 32751457

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