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 [1].

Health Benefits of L. paracasei

1) Boosts Immunity

Dietary supplementation with cow’s milk or rice fermented with L. paracasei prevents common infectious disease (CIDs) in children attending daycare [2].

L. paracasei is an enhancer of systemic immunity in mice [3]. This bacterium skews the Th1/Th2 balance toward Th1 through the elevation of Th1 cytokine production [4, 5].

L. paracasei enhances natural killer (NK) cell activity, lymphocyte proliferation and antibody production in mice [6, 7, 8].

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 [9, 10].

L. paracasei increases E. coli infection survival in mice [8].

Both L. paracasei and its supernatant enhance innate immunity through the activation of Toll-like receptor (TLR) signaling [11].

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) [12].

L. paracasei decreases pro-inflammatory cytokines and chemokines in human intestinal DCs challenged with Salmonella [11, 13].

2) 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 [14].

L. paracasei has allergy reducing effects in mice, by balancing the Th1/Th2 responses [15].

L. paracasei induces Th1 and regulatory responses in mice, suppresses airway inflammation, and down-regulates allergen-specific immune responses [16, 17, 17].

L. paracasei administration to mothers during gestation/lactation protects against airway inflammation in offspring in mice [16].

L. paracasei Alleviates Allergic Rhinitis

At least five clinical studies with L. paracasei demonstrated clinically significant improvements in allergic rhinitis [18], one did not [19].

Subjects with a medical history of allergic rhinitis to grass pollen that received L. paracasei -fermented milk had lower nasal congestion and nasal itching [20].

In children with perennial allergic rhinitis, L. paracasei improved symptoms of sneezing, itchy nose, and swollen eyes [21].

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 [22].

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 [23].

3) Antibacterial Properties

L. paracasei inhibits common pathogens including Shigella dysenteriae, Staphylococcus aureus, Cronobacter sakazakii, Escherichia coli, and Candida albicans in the laboratory [24, 25].

Fermented milk with L. paracasei significantly improved gut microbiota, increased Lactobacilli, and inhibited the colonization of C. albicans to the intestines of mice [24].

A bacteriocin produced by L. paracasei inhibits P. gingivalis associated with periodontal disease [26].

4) Beneficial for Dental Health

Oral L. paracasei significantly reduced salivary S. mutans [27, 28, 29], and increased Lactobacilli in adults [29].

However, L. paracasei was not found efficient in 9-year-old children [30].

L. paracasei, even if heat-killed, inhibits S. mutans and decreases caries lesions in rats [31].

5) Beneficial for the GI Tract

L. paracasei Improves Intestinal Microflora

L. paracasei increases the number of Bifidobacteria and Lactobacilli in human subjects [32, 33].

Oral intake of L. paracasei by mice increases intestinal Bifidobacteria and Lactobacilli [5, 7], and decreased the content of Clostridium perfringens [7].

L. paracasei antagonizes Escherichia coli and Clostridium species [34, 33].

L. paracasei further increases acetic acid and butyric acid, while it decreases ammonia [33].

L. paracasei Strengthens the Intestinal Barrier

L. paracasei modulates intestinal digestion, absorption of nutrients, energy metabolism, lipid synthesis and intestinal protective functions in mice [35].

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 [36].

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 [37, 38].

L. paracasei therapy prevents antibiotic induced visceral hypersensitivity and restores normal gut permeability in rats [39].

L. paracasei is Beneficial in Diverticular Disease

L. paracasei, in association with a high-fiber diet, is effective in reducing abdominal bloating and prolonged abdominal pain in patients with symptomatic uncomplicated diverticular disease [40].

L. paracasei Ameliorates Diarrhea

L. paracasei effectively resolves acute diarrhea [41] and ameliorates non-rotavirus-induced diarrhea in children [42].

L. paracasei Relieves Constipation

L. paracasei relieves constipation [43].

L. paracasei Ameliorates GI Inflamamation

L. paracasei prevents intestinal inflammation in mice with colitis [44].

Oral supplementation of L. paracasei reduced the clinical progression of necrotizing enterocolitis in infants [45].

L. paracasei May Alleviate IBS

L. paracasei supplementation prevents bowel symptom onset in patients on long-term proton pump inhibitors [46].

L. paracasei normalizes muscular activity and energy metabolism and elevates lipid breakdown in mice with irritable bowel syndrome (IBS) [47].

L. paracasei attenuates muscle hypercontractility and Th-2 levels in mice with post-infective irritable bowel syndrome (IBS) [48].

6) May Improve Liver Function

L. paracasei lowers liver fat deposition and serum ALT level in mice with nonalcoholic steatohepatitis (NASH) [49].

L. paracasei reduces total blood and liver cholesterol in rats and decreases liver damage due to alcohol intake [50].

L. paracasei restores gut microbiota and attenuates ischemia/reperfusion-related liver injury in rats [51].

L. paracasei symbiotic (containing arabinogalactan, fructooligosaccharides) lessens NAFLD progression in rats, lowers inflammatory markers, and reduces the severity of liver injury and insulin resistance [52].

7) May Ameliorate Insulin Resistance

L. paracasei symbiotic improves many aspects of insulin resistance, such as fasting response, hormonal homeostasis, and glycemic control in rats [52].

8) 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) [53].

In another study, long-term ingestion of L. paracasei reduced body weight and abdominal fat weight in rats [54].

L. paracasei decreased body fat in mice [55].

L. paracasei decreases triacylglycerol in human subjects [56].

L. paracasei decreases energy/food intake in both human and animal subjects [57].

9) 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 [58].

L. paracasei decreases skin sensitivity and increases barrier function recovery (water retention) in women [59].

L. paracasei Improves Atopic Dermatitis

Heat-killed L. paracasei improved atopic dermatitis (AD) in adult patients [60].

10) 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 [61].

11) May Prevent Urogenital Infections

L. paracasei prevents urogenital infections by inhibiting Staphylococcus aureus in mice [62].

12) Combats Cancer

Both viable and nonviable L. paracasei exert the same antiproliferative and proapoptotic effects on gastric and colorectal cancer cells in the laboratory [63].

L. paracasei significantly inhibits colon cancer cell proliferation [64].


  • Depending on the experimental setting, L. paracasei has different effects on cytokines.
  • It both elevates and suppresses pro-inflammatory cytokines TNF-α [36, 37, 38, 4, 65], decreases [38, 44] or increases IL-1β [4, 65], and inhibits [36] or elevates IFN-γ [4, 65].
  • L. paracasei mostly induces IL-12 [10, 66, 4, 9] [in some studies decreases: 12, 44], and increases the proportion of NK cells [9], while reducing the Th-2 response [48, 67].
  • L. paracasei mostly increases IL-10 [37, 4, 65, 68] [ a study where IL-10 is decreased: 12].
  • L. paracasei decreases TGF-β1[12, 48], and increases TGF-β2 [12].
  • L. paracasei increases IL-8 [12], decreases IL-2, IL-4, IL-5, and IL-13 [4, 16, 20, 49]. and both decreases and increases IL-6 [44, 12].
  • L. paracasei increases IgA [65, 68], and decreases IgG4 [20] and IgE [67].
  • L. paracasei stimulates iNOS and NO [4].
  • L. paracasei increases RANTES, IP-10 [12] and ANGPTL4 [55].
  • L. paracasei lowers PPAR-γ [49, 53].
  • It decreases MIP-1α [12], CCL-20 [36], PTGS2 [37], COX-2, PGE2 [48], TLR-4, NOX-4, MCP-1, PPAR-δ [49], CCAAT/ C/EBPβ, C/EBPα and HR-LPL [53].
  • L. paracasei increases CD4+ T cell and B cell proliferation [65] and upregulates the CD4+CD25+Foxp3+Treg cell responses [15].
  • It reduces neutrophil infiltration [44] and attenuates eosinophil influx in the lungs [67, 16, 20].
  • L. paracasei increases the expression of almost all TLR signaling genes [12].


Oral administration of L. paracasei had no adverse effects in mice [69] and rats [70].

However, the use of probiotics should be avoided in patients with organ failure, immunocompromised status, and dysfunctional gut barrier mechanisms, where L. paracasei can cause infection [71].

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About the Author

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

Dr. Biljana Novkovic, PhD

PhD (Ecological Genetics)

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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