L. casei

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Health Goals: digestion immunity inflammation

Research Overview

Across the provided abstracts, Lactobacillus casei research is most developed in three areas: (1) host–microbiome–immune interactions relevant to inflammatory disease (notably rheumatoid arthritis models), (2) human stress-related gastrointestinal outcomes using the well-characterized strain L. casei Shirota, and (3) applied food/biotechnology, including use as a fermentation starter (e.g., elderberry juice) and as a functional ingredient in dairy matrices (e.g., probiotic/synbiotic ice cream). A smaller but distinct line of work examines L. casei as a microbial platform for biogenic synthesis of selenium nanoparticles, with downstream testing of cytotoxicity and antioxidant/cell-death pathways in vitro.

The strongest evidence in these abstracts supports two conclusions. First, in humans under acute psychological stress, daily consumption of L. casei strain Shirota in a double-blind, placebo-controlled trial was associated with reduced stress-associated abdominal symptoms, blunted salivary cortisol increases, and measurable shifts in gut microbiota features (e.g., higher alpha-diversity and lower Bacteroidaceae), alongside reduced stress-associated leukocyte gene-expression perturbations. Second, in preclinical rheumatoid arthritis (collagen-induced arthritis) models, enrichment or mono-colonization with L. casei (and L. paracasei) is linked to reduced disease severity in a microbiota-dependent manner, plausibly mediated through increased microbial tryptophan-derived indoles (e.g., IA, IPA, IAA) that activate AhR and influence Th17/Treg balance; however, in these studies L. casei is part of a broader mechanistic chain involving a drug (sinomenine), community-level microbiome changes, and metabolite signaling rather than an isolated single-factor intervention.

Key gaps include the need for more rigorous, strain-resolved and disease-specific clinical trials beyond stress-associated symptoms—particularly to test causality and generalizability of immune and anti-inflammatory effects suggested by animal RA work. Mechanistically, more research is needed to disentangle direct effects of L. casei from co-occurring microbiome shifts, to quantify relevant metabolite production in vivo (e.g., indole derivatives) and link these to validated host endpoints, and to establish dose–response, durability, and safety across populations. In applied contexts, variability among L. casei strains in fermentation performance and functional outputs (volatile profiles, survival through GI conditions, epithelial adhesion, and bioactivities such as ACE-inhibition/antioxidant capacity) indicates a need for standardized strain characterization and comparative studies; similarly, selenium nanoparticle work remains largely in vitro and requires translational evaluation of bioavailability, efficacy, and safety in vivo.

1. What conditions has L. casei been studied for?

  • Rheumatoid arthritis (RA)/inflammatory arthritis models: Studied in a collagen-induced arthritis (CIA) rat model in the context of gut microbiota modulation and tryptophan metabolites/AhR signaling; L. casei was identified as one of two “beneficial anti-CIA” Lactobacillus species enriched and tested via mono-colonization.

  • Stress-associated abdominal dysfunction / GI symptoms under acute stress: Studied in healthy medical students during examination stress using Lactobacillus casei strain Shirota in a double-blind, placebo-controlled trial.

  • Helicobacter pylori-associated inflammation/oxidative stress and gastric mucosal injury: Studied using Lacticaseibacillus casei T1 in cell and animal experiments (anti-inflammatory and antioxidant outcomes; gastric mucosal protection).

  • Food/functional food applications with potential health relevance:

    • Probiotic delivery/viability: Encapsulation in nanochitin–whey protein microcapsules and tablets to improve viability and sustained release (formulation research).

    • Synbiotic dairy dessert: L. casei 01 in sheep milk ice cream (viability, simulated GI survival, Caco-2 adhesion; ACE-inhibitory and antioxidant activity, especially with inulin).

    • Fermented plant beverages/juices: Fermentation of quinoa beverages (with L. casei CRL 431) affecting phenolics/antioxidant capacity; black raspberry juice fermentation (with an L. casei strain) showing anti-adhesion vs Salmonella typhimurium in Caco-2 cells; elderberry juice fermentation (some L. casei strains) altering volatile/aroma profiles.

  • Selenium nanoparticle (SeNP) biotransformation and antioxidant/cytotoxic effects (in vitro): L. casei ATCC 393 used to biosynthesize SeNPs; SeNPs evaluated for cytotoxicity and antioxidant effects in cell models.

2. Does it work in treating those conditions? Summarize the evidence.

  • Stress-associated abdominal dysfunction (human RCT): Evidence suggests benefit in this specific setting. In a double-blind, placebo-controlled trial in healthy students under exam stress, daily intake of L. casei strain Shirota for 8 weeks:

    • Significantly suppressed stress-induced increases in abdominal dysfunction scores and GI symptoms versus placebo.

    • Placebo group showed a significant pre-exam rise in salivary cortisol; this rise was not observed in the L. casei group.

    • Gut microbiota changes included higher alpha-diversity (more species) and lower Bacteroidaceae percentage versus placebo.

    Limitations: Small sample size (23 vs 24), healthy participants (not IBS patients), and strain-specific findings (Shirota).

  • Rheumatoid arthritis / CIA model (preclinical): Evidence is suggestive but indirect and animal-based. In the CIA rat work, the anti-arthritis drug sinomenine (SIN) improved arthritis in a gut-microbiota-dependent manner and was linked to enrichment of L. casei (and L. paracasei) and increased microbial tryptophan metabolites (IA, IPA, IAA) that activated AhR and influenced Th17/Treg balance. The abstract states L. casei and L. paracasei were “beneficial anti-CIA” species tested by mono-colonization.

    Interpretation: This supports a plausible mechanistic role for L. casei in reducing arthritis severity in an animal model, but it does not establish clinical efficacy in human RA, and the benefit is presented within a SIN-driven microbiome mechanism.

  • H. pylori-associated inflammation/oxidative stress (cell + animal): L. casei T1 reduced inflammatory cytokine overexpression in gastric epithelial cells (GES-1) and, with long-term administration in animals, reduced oxidative stress and inflammatory cytokines and improved gastric mucosal damage in infected mice. It also shifted gut microbiota toward higher relative abundance of “beneficial” taxa (Lachnospiraceae, Odoribacter).

    Limitations: Preclinical; not an eradication trial in humans; the authors note future study combining with antibiotics is needed.

  • Anti-pathogen adhesion (in vitro): Fermented black raspberry juice containing LAB including an L. casei strain showed significant anti-adhesion activity against Salmonella typhimurium in Caco-2 cells. This is supportive of a barrier/colonization-resistance mechanism but is not clinical evidence.

  • Other areas (CRC, RA reviews, food fermentation): Some abstracts are incomplete or are general reviews noting “insufficient evidence” for probiotics in RA overall. Food fermentation studies mainly show biochemical/quality changes (e.g., volatiles, phenolics) rather than treatment outcomes.

3. What health benefits does it have?

  • May reduce stress-associated GI symptoms and stress physiology (strain Shirota): In stressed healthy students, L. casei strain Shirota reduced abdominal dysfunction symptoms and blunted stress-related changes (including cortisol rise seen in placebo), and preserved gut microbiota diversity.

  • Immunomodulatory potential via microbiome metabolites (preclinical): In CIA rats, enrichment of L. casei was linked to higher microbial tryptophan metabolites (IA, IPA, IAA) and AhR activation with downstream Th17/Treg balance effects—mechanistically consistent with anti-inflammatory potential.

  • Anti-inflammatory and antioxidant effects in H. pylori models (strain T1): Reduced inflammatory cytokines and oxidative stress markers and improved gastric mucosal injury in infected animals; also helped maintain intestinal microflora balance.

  • Potential support for gut barrier/colonization resistance (in vitro): Fermented black raspberry juice with L. casei showed anti-adhesion activity against S. typhimurium in intestinal epithelial cells.

  • Functional food benefits (product-level):

    • Probiotic viability and delivery: Encapsulation approaches (nanochitin–WPI microcapsules/tablets) improved viability and provided sustained release characteristics (formulation benefit).

    • Survival through simulated GI conditions and adhesion: L. casei 01 remained above 6 log CFU/mL in ice cream over 150 days and showed survival in simulated GI passage and adhesion to Caco-2 cells; inulin improved ACE-inhibitory and antioxidant activity of the product without harming survival/adhesion.

    • Enhanced antioxidant-related phytochemicals in fermented beverages: Fermentation with L. casei CRL 431 increased free phenolics/flavonoids and antioxidant capacities in quinoa beverages versus unfermented controls (food matrix effect; not direct clinical benefit).

  • Biotransformation of selenium (in vitro): L. casei ATCC 393 converted sodium selenite to intracellular SeNPs; extracted SeNPs showed lower toxicity than sodium selenite/selenium methionine in a normal epithelial cell line and had antioxidant activity in oxidative stress models (cell-based).

4. Does it have any downsides or side effects?

  • Human tolerability in the provided abstracts: In the exam-stress RCT, no specific adverse events are described in the abstract; the focus is on symptom reduction and stress markers. Absence of reported harms in an abstract is not proof of safety, but it suggests no obvious signal in that small study.

  • Potential strain- and context-specific effects: The benefits and microbiome shifts are strain-specific (e.g., Shirota, T1, 01, CRL 431). Effects (and tolerability) may not generalize across all L. casei strains or products.

  • In vitro cytotoxicity context (selenium nanoparticles): While SeNPs biosynthesized by L. casei ATCC 393 were reported as less toxic than sodium selenite and selenium methionine and non-cytotoxic to a normal epithelial cell line below 25 μg Se/mL, they also induced apoptosis in HepG2 cancer cells via caspase signaling. This is not a “side effect” of consuming L. casei per se, but it highlights that bioactive metabolites/materials associated with microbial processes can have dose- and context-dependent biological effects.

  • General evidence limitations: Several findings are preclinical (cell/animal) or food-technology focused; these do not establish real-world risk profiles in diverse human populations (e.g., immunocompromised individuals), and the abstracts provided do not address rare adverse events.

5. Is it beneficial or harmful for any genetic variations (pharmacogenomics)?

The provided abstracts do not report pharmacogenomic analyses (i.e., outcomes stratified by human genetic variants) for L. casei. No specific gene–probiotic interactions, genotype-based dosing, or genetically defined responder/non-responder patterns are described.

  • Indirect mechanistic note (not pharmacogenomics): The CIA rat abstract emphasizes activation of the aryl hydrocarbon receptor (AhR) pathway by microbial tryptophan metabolites associated with L. casei enrichment. While this suggests a host signaling pathway that could, in theory, vary by genetics, the abstract does not test genetic variants or differential responses.

References

  1. Sinomenine ameliorates rheumatoid arthritis by modulating tryptophan metabolism and activating aryl hydrocarbon receptor via gut microbiota regulation.
    Zheng-Meng Jiang, Su-Ling Zeng, Tian-Qing Huang, Yang Lin, Fang-Fang Wang, Xing-Jiao Gao, Jing Li, Ping Li, E-Hu Liu (2023) - Science bulletin
  2. Fermented Milk Containing Lactobacillus casei Strain Shirota Preserves the Diversity of the Gut Microbiota and Relieves Abdominal Dysfunction in Healthy Medical Students Exposed to Academic Stress.
    Akito Kato-Kataoka, Kensei Nishida, Mai Takada, Mitsuhisa Kawai, Hiroko Kikuchi-Hayakawa, Kazunori Suda, Hiroshi Ishikawa, Yusuke Gondo, Kensuke Shimizu, Takahiro Matsuki, Akira Kushiro, Ryoutaro Hoshi, Osamu Watanabe, Tomoki Igarashi, Kouji Miyazaki, Yuki Kuwano, Kazuhito Rokutan (2016) - Applied and environmental microbiology
  3. Preparation, characteristics and antioxidant activity of polysaccharides and proteins-capped selenium nanoparticles synthesized by Lactobacillus casei ATCC 393.
    Chunlan Xu, Lei Qiao, Yu Guo, Li Ma, Yiyi Cheng (2018) - Carbohydrate polymers
  4. Volatile profile of elderberry juice: Effect of lactic acid fermentation using L. plantarum, L. rhamnosus and L. casei strains.
    Annalisa Ricci, Martina Cirlini, Alessia Levante, Chiara Dall'Asta, Gianni Galaverna, Camilla Lazzi (2018) - Food research international (Ottawa, Ont.)
  5. Probiotic Strain
    Elsa Jacouton, Florian Chain, Harry Sokol, Philippe Langella, Luis G Bermúdez-Humarán (2017) - Frontiers in immunology
  6. The addition of inulin and Lactobacillus casei 01 in sheep milk ice cream.
    Celso F Balthazar, Hugo L A Silva, Erick A Esmerino, Ramon S Rocha, Jeremias Moraes, Mariana A V Carmo, Luciana Azevedo, Ihosvany Camps, Yuri K D Abud, Celso Sant'Anna, Robson M Franco, Mônica Q Freitas, Marcia C Silva, Renata S L Raices, Graziela B Escher, Daniel Granato, C Senaka Ranadheera, Filomena Nazarro, Adriano G Cruz (2018) - Food chemistry
  7. Probiotic Supplementation for Rheumatoid Arthritis: A Promising Adjuvant Therapy in the Gut Microbiome Era.
    Margarida Ferro, Sofia Charneca, Eduardo Dourado, Catarina Sousa Guerreiro, João Eurico Fonseca (2021) - Frontiers in pharmacology
  8. Preparation and characterization of microcapsules and tablets for probiotic encapsulation via whey protein isolate-nanochitin complex coacervation.
    Mengxin Luo, Le Ma, Yuxi Guo, Caihong Zhu, Junjie Chen, Bin Zhang, Jianguo Zhu, Matt Jellicoe, Shan He, Yucong Zou, Yang Yuan (2025) - International journal of biological macromolecules
  9. Enrichment of set yoghurt with flaxseed oil, flaxseed mucilage and free or encapsulated
    Abdollah Shafizadeh, Leila Golestan, Mohammad Ahmadi, Pegah Darjani, Azade Ghorbani-HasanSaraei (2024) - Food science and technology international = Ciencia y tecnologia de los alimentos internacional
  10. Effect of Lactobacillus (L. acidophilus NCIB1899, L. casei CRL 431, L. paracasei LP33) fermentation on free and bound polyphenolic, antioxidant activities in three Chenopodium quinoa cultivars.
    Jigang Zhang, Xudong Huang, Jianghua Cheng, Chuyan Wang (2023) - Journal of food science
  11. Lacticaseibacillus casei T1 attenuates Helicobacter pylori-induced inflammation and gut microbiota disorders in mice.
    Zhihao Yu, Mei Cao, Jingshan Peng, Daoyan Wu, Shu Li, Chengmeng Wu, Liting Qing, Andong Zhang, Wenjie Wang, Min Huang, Jian Zhao (2023) - BMC microbiology
  12. Fermentation of Rubus dolichocarpus juice using Lactobacillus gasseri and Lacticaseibacillus casei and protecting phenolic compounds by Stevia extract during cold storage.
    Mohammad Mahdi Karimkhani, Abdollah Jamshidi, Mahmoud Nasrollahzadeh, Mohammad Armin, Seid Mahdi Jafari, Tayebeh Zeinali (2024) - Scientific reports
  13. Effect of Lactobacillus paracasei subsp. paracasei, L. casei 431 on immune response to influenza vaccination and upper respiratory tract infections in healthy adult volunteers: a randomized, double-blind, placebo-controlled, parallel-group study.
    Lillian Jespersen, Inge Tarnow, Dorte Eskesen, Cathrine Melsaether Morberg, Birgit Michelsen, Susanne Bügel, Lars Ove Dragsted, Ger T Rijkers, Philip C Calder (2015) - The American journal of clinical nutrition
  14. Antimicrobial photodynamic therapy against Lactobacillus casei using curcumin, nano-curcumin, or erythrosine and a dental LED curing device.
    Farzaneh Ahrari, Fatemeh Mazhari, Kiarash Ghazvini, Reza Fekrazad, Shaho Menbari, Morteza Nazifi (2023) - Lasers in medical science
  15. Probiotics as a New Regulator for Bone Health: A Systematic Review and Meta-Analysis.
    Hanieh Malmir, Hanieh-Sadat Ejtahed, Ahmad-Reza Soroush, Amir Mohammad Mortazavian, Noushin Fahimfar, Afshin Ostovar, Ahmad Esmaillzadeh, Bagher Larijani, Shirin Hasani-Ranjbar (2021) - Evidence-based complementary and alternative medicine : eCAM
  16. Effect of salt on cell viability and membrane integrity of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium longum as observed by flow cytometry.
    Akanksha Gandhi, Nagendra P Shah (2015) - Food microbiology
  17. Reducing Immunoreactivity of Gluten Peptides by Probiotic Lactic Acid Bacteria for Dietary Management of Gluten-Related Diseases.
    Joanna Leszczyńska, Agnieszka K Szczepankowska, Iwona Majak, Dorota Mańkowska, Beata Smolińska, Sylwia Ścieszka, Anna Diowksz, Bożena Cukrowska, Tamara Aleksandrzak-Piekarczyk (2024) - Nutrients
  18. Effect of cassava pulp treated with
    Sunisa Pongsub, Chaichana Suriyapha, Waewaree Boontiam, Anusorn Cherdthong (2024) - Heliyon
  19. Investigating the properties and antibacterial, antioxidant, and cytotoxicity activity of postbiotics derived from Lacticaseibacillus casei on various gastrointestinal pathogens in vitro and in food models.
    Zahra Asadi, Amin Abbasi, Ali Ghaemi, Effat Abbasi Montazeri, Sousan Akrami (2024) - GMS hygiene and infection control
  20. Probiotic Characteristics and Safety Assessment ofLacticaseibacillus caseiKGC1201 Isolated fromPanax ginseng
    Yun-Seok Lee, Hye-Young Yu, Mijin Kwon, Seung-Ho Lee, Ji-In Park (2023)


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