L. paracasei  boosts the immune system, balances the GI microbiota, ameliorates allergic symptoms and decreases skin sensitivity. And these are only some of the L. paracasei  many health benefits.

What is Lactobacillus paracasei?

Lactobacillus paracasei  is a gram-positive lactic acid bacterium, commonly used in dairy products and probiotics. Both L. paracasei  and its fermented products are effective immunomodulators, they alleviate allergies, prevent gastric mucosal lesions and inhibit fat tissue accumulation (R).

Health Benefits of L. paracasei

1) L. paracasei  Boosts Immunity

Dietary supplementation with cow’s milk or rice fermented with L. paracasei  prevents common infectious disease (CIDs) in children attending daycare (R).

L. paracasei  is an enhancer of systemic immunity in mice (R). This bacterium skews the Th1/Th2 balance toward Th1 through the elevation of Th1 cytokine production (R,R).

L. paracasei  enhances natural killer (NK) cell activity, lymphocyte proliferation and antibody production in mice (R,R,R).

L. paracasei  strongly induces IL-12, increases the proportion of natural killer (NK) cells in the spleen, and ameliorates the symptoms of influenza virus infection in mice (R,R).

L. paracasei  increases E. coli infection survival in mice (R).

Both L. paracasei  and its supernatant enhance innate immunity through the activation of Toll-like receptor (TLR) signaling (R).

L. paracasei  Differentially Modulates Inflammation

L. paracasei  significantly increases the release of pro-inflammatory cytokines and stimulates the innate immune system in human enterocytes and dendritic cells (DCs) (R).

L. paracasei  decreases pro-inflammatory cytokines and chemokines in human intestinal DCs challenged with Salmonella (R,R).

2) L. paracasei  is Beneficial in Allergies

A significant reduction of nasal symptoms and improved quality of life were achieved in patients with Japanese cedar pollinosis, who received L. paracasei  when pollen scattering was low. However, the effects were limited during the peak period (R).

L. paracasei  has allergy reducing effects in mice, by balancing the Th1/Th2 responses (R).

L. paracasei  induces Th1 and regulatory responses in mice, suppresses airway inflammation and down-regulates allergen-specific immune responses (R,R,R).

L. paracasei  administration to mothers during gestation/lactation protects against airway inflammation in offspring in mice (R).

L. paracasei  Alleviates Allergic Rhinitis

At least five clinical studies with L. paracasei  demonstrated clinically significant improvements in allergic rhinitis (R), one did not (R).

Subjects with a medical history of allergic rhinitis to grass pollen that received L. paracasei -fermented milk had lower nasal congestion and nasal itching (R).

In children with perennial allergic rhinitis, L. paracasei  improved symptoms of sneezing, itchy nose, and swollen eyes (R).

L. paracasei  improves the quality of life of subjects with persistent allergic rhinitis who are being treated with an oral H1-antihistamine. In this study, nasal symptoms had not changed, but ocular symptoms had consistently improved (R).

Heat-killed L. paracasei  can effectively improve the overall quality of life for patients with allergic rhinitis induced by house dust mite in human subjects (R).

3) L. paracasei  has Antibacterial Properties

L. paracasei  inhibits common pathogens including Shigella dysenteriae, Staphylococcus aureus, Cronobacter sakazakii, Escherichia coli, and Candida albicans in the laboratory (R,R).

Fermented milk with L. paracasei  significantly improved gut microbiota, increased Lactobacilli, and inhibited the colonization of C. albicans to the intestines of mice (R).

A bacteriocin produced by L. paracasei  inhibits P. gingivalis associated with periodontal disease (R).

4) L. paracasei  is Beneficial for Dental Health

Oral L. paracasei  significantly reduced salivary S. mutans (R,R,R), and increased Lactobacilli in adults (R).

However, L. paracasei  was not found efficient in 9-year-old children (R).

L. paracasei, even if heat-killed, inhibits S. mutans and decreases caries lesions in rats (R).

5) L. paracasei is Beneficial for the GI Tract

L. paracasei  Improves Intestinal Microflora

L. paracasei  increases the number of Bifidobacteria and Lactobacilli in human subjects (R,R).

Oral intake of L. paracasei  by mice increases intestinal Bifidobacteria and Lactobacilli (R,R), and decreased the content of Clostridium perfringens (R).

L. paracasei  antagonizes Escherichia coli and Clostridium species (R,R).

L. paracasei  further increases acetic acid and butyric acid, while it decreases ammonia (R).

L. paracasei  Strengthens the Intestinal Barrier

L. paracasei  modulates intestinal digestion, absorption of nutrients, energy metabolism, lipid synthesis and intestinal protective functions in mice (R).

Fermented milk with L. paracasei  promotes intestinal epithelial cell growth and intestinal epithelial integrity to strengthen the intestinal barrier against chemical and inflammatory stimuli-induced damage (R).

L. paracasei  synbiotic therapy can prevent or repair colon damage in mice with acute colitis, where this bacterium completely restores epithelial barrier integrity and gut protection (R,R).

L. paracasei  therapy prevents antibiotic induced visceral hypersensitivity and restores normal gut permeability in rats (R).

L. paracasei  is Beneficial in Diverticular Disease

L. paracasei, in association with a high-fibre diet, is effective in reducing abdominal bloating and prolonged abdominal pain in patients with symptomatic uncomplicated diverticular disease (R).

L. paracasei  Ameliorates Diarrhea

L. paracasei  effectively resolves acute diarrhea (R) and ameliorates non-rotavirus-induced diarrhea in children (R).

L. paracasei  Relieves Constipation

L. paracasei  relieves constipation (R).

L. paracasei  Ameliorates GI Inflamamation

L. paracasei  prevents intestinal inflammation in mice with colitis (R).

Oral supplementation of L. paracasei  reduced the clinical progression of necrotizing enterocolitis in infants (R).

L. paracasei  May Alleviate IBS

L. paracasei  supplementation prevents bowel symptom onset in patients on long-term proton pump inhibitors (R).

L. paracasei  normalizes muscular activity and energy metabolism and elevates lipid breakdown in mice with irritable bowel syndrome (IBS) (R).

L. paracasei  attenuates muscle hypercontractility and Th-2 levels in mice with postinfective irritable bowel syndrome (IBS) (R).

6) L. paracasei  May Improve Liver Function

L. paracasei  lowers liver fat deposition and serum ALT level in mice with nonalcoholic steatohepatitis (NASH) (R).

L. paracasei  reduces total blood and liver cholesterol in rats and decrease liver damage due to alcohol intake (R).

L. paracasei  restores gut microbiota and attenuates ischemia/reperfusion-related liver injury in rats (R).

L. paracasei  symbiotic (containing arabinogalactan, fructooligosaccharides) lessens NAFLD progression in rats, lowers inflammatory markers and reduces the severity of liver injury and insulin resistance (R).

7) L. paracasei  May Ameliorate Insulin Resistance

L. paracasei  symbiotic improves many aspects of insulin resistance, such as fasting response, hormonal homeostasis, and glycemic control in rats (R).

8) L. paracasei  Combats Obesity

Water extract of L. paracasei  reduces body weight in obese rats. It decreases the formation of lipid plaques in the aorta, reduces fat cell size and inhibits fat absorption, thereby reducing fat production (lipogenesis) (R).

In another study, long-term ingestion of L. paracasei  reduced body weight and abdominal fat weight in rats (R).

L. paracasei  decreased body fat in mice (R).

L. paracasei  decreases triacylglycerol in human subjects (R).

L. paracasei  decreases energy/food intake in both human and animal subjects (R).

9) L. paracasei  is Great for the Skin

L. paracasei  contributes to the reinforcement of skin barrier function, inhibits water loss, decreases skin sensitivity and modulates the skin immune system leading to the preservation of skin homeostasis (R).

L. paracasei  decreases skin sensitivity and increases barrier function recovery (water retention) in women (R).

L. paracasei  Improves Atopic Dermatitis

Heat-killed L. paracasei  improved atopic dermatitis (AD) in adult patients (R).

10) L. paracasei  May Combat Toxins

L. paracasei  reduced the adverse effects of Zearalenone (ZEN), an estrogenic toxin produced by numerous Fusarium fungi species in pre- or post-harvest cereals in mice (R).

11) L. paracasei  May Prevent Urogenital Infections

L. paracasei prevents urogenital infections by inhibiting Staphylococcus aureus in mice (R).

12) L. paracasei  Combats Cancer

Both viable and nonviable L. paracasei  exert the same antiproliferative and proapoptotic effects on gastric and colorectal cancer cells in the laboratory (R).

L. paracasei  significantly inhibits colon cancer cell proliferation (R).


  • Depending on the experimental setting, L. paracasei  has different effects on cytokines.
  • It both elevates and suppresses pro-inflammatory cytokines TNF-α (R,R,R,R,R), decreases (R,R) or increases IL-1β (R,R), and inhibits (R) or elevates IFN-γ (R,R).
  • L. paracasei  mostly induces IL-12 (R,R,R,R) (in some studies decreases: R,R), and increases the proportion of NK cells (R), while reducing the Th-2 response (R,R).
  • L. paracasei  mostly increases IL-10 (R,R, R,R) ( a study where IL-10 is decreased: R).
  • L. paracasei  decreases TGF-β1(R,R), and increases TGF-β2 (R).
  • L. paracasei  increases IL-8 (R), decreases IL-2, IL-4, IL-5, and IL-13 (R,R, R,R). and both decreases and increases IL-6 (R,R).
  • L. paracasei  increases IgA (R, R), and decreases IgG4 (R) and IgE (R).
  • L. paracasei  stimulates iNOS and NO (R).
  • L. paracasei  increases RANTES, IP-10 (R) and ANGPTL4 (R).
  • L. paracasei  lowers PPAR-γ (R,R).
  • It decreases MIP-1α (R), CCL-20 (R), PTGS2 (R), COX-2, PGE2 (R), TLR-4, NOX-4, MCP-1, PPAR-δ (R), CCAAT/ C/EBPβ, C/EBPα and HR-LPL (R).
  • L. paracasei  increases CD4+ T cell and B cell proliferation (R) and upregulates the CD4+CD25+Foxp3+Treg cell responses (R).
  • It reduces neutrophil infiltration (R) and attenuates eosinophil influx in the lungs (R,R,R).
  • L. paracasei  increases the expression of almost all TLR signaling genes (R).


Oral administration of L. paracasei  had no adverse effects in mice (R) and rats (R).

However, use of probiotics should be avoided in patients with organ failure, immunocompromised status, and dysfunctional gut barrier mechanisms, where L. paracasei  can cause infection (R).

About the Author

Biljana Novkovic - PHD (ECOLOGICAL GENETICS) - Writer at Selfhacked

Dr. Biljana Novkovic, PhD


Biljana received her PhD from Hokkaido University.

Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science & health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.

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