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Lactobacillus paracasei is commonly found in our intestinal tracts and mouths as well as in many dairy products and the environment (1,10,13). It is part of the Firmucutes phylum which is the most abundant bacteria in the gut. Its name denotes it lactic acid generating ability as well as its rod shape (bacillus). It is very is very similar to lactobacillus casei and lactobacillus rhamnousus, but each have slightly different fermentation properties (3-5). There are some 34 strains of Lactobacillus paracasei (2).

In general Lactobacillus have been found to stimulate aspects of the immune response and two of the strains of Lactobacillus paracasei have been found to inhibit Salmonella enterica and Heliobacter pylori, two pathogens commonly found in the gastrointestinal tract (6). It may have a number of clinical applications (7) and has been studied as part of a nutritional supplement to work with other bacteria and in combination with conventional therapies to treat ulcerative colitis (8).



  1. Orlando, A.; Refolo, M. G.; Messa, C.; Amati, L.; Lavermicocca, P.; Guerra, V.; Russo, F. (October 2012). “Antiproliferative and Proapoptotic Effects of Viable or Heat-Killed IMPC2.1 and GG in HGC-27 Gastric and DLD-1 Colon Cell Lines”. Nutrition and Cancer. 64 (7): 1103–1111. doi:10.1080/01635581.2012.717676.
  2. Smokvina, Tamara; Wels, Michiel; Polka, Justyna; Chervaux, Christian; Brisse, Sylvain; Boekhorst, Jos; Vlieg, Johan E. T. van Hylckama; Siezen, Roland J.; Highlander, Sarah K. (19 July 2013). “Lactobacillus paracasei Comparative Genomics: Towards Species Pan-Genome Definition and Exploitation of Diversity”. PLoS ONE. 8 (7): e68731. doi:10.1371/journal.pone.0068731.
  3. COLLINS, M. D.; PHILLIPS, B. A.; ZANONI, P. (1 April 1989). “Deoxyribonucleic Acid Homology Studies of Lactobacillus casei, Lactobacillus paracasei sp. nov., subsp. paracasei and subsp. tolerans, and Lactobacillus rhamnosus sp. nov., comb. nov.”. International Journal of Systematic Bacteriology. 39 (2): 105–108. doi:10.1099/00207713-39-2-105.
  4. Ward, L. J. H.; Timmins, M. J. (August 1999). “Differentiation of Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus by polymerase chain reaction”. Letters in Applied Microbiology. 29 (2): 90–92. doi:10.1046/j.1365-2672.1999.00586.x.
  5. Felten, A; Barreau, C; Bizet, C; Lagrange, PH; Philippon, A (Mar 1999). “Lactobacillus species identification, H2O2 production, and antibiotic resistance and correlation with human clinical status.”. Journal of clinical microbiology. 37 (3): 729–33. PMID 9986841.
  6. HESSLE; HANSON,; WOLD, (May 1999). “Lactobacilli from human gastrointestinal mucosa are strong stimulators of IL-12 production”. Clinical and Experimental Immunology. 116 (2): 276–282. doi:10.1046/j.1365-2249.1999.00885.x.
  7.  Sgouras, SD. et al.; (Jan. 2004) In Vitro and In Vivo Inhibition of Helicobacter pylori by Lactobacillus casei Strain Shirota. Applied and Enviornmental Microbiology, Vol. 70, No. 10099-2240/04/p. 518–526,:DOI: 10.1128/AEM.70.1.518–526.2004
  8. Bernstein, Charles N; Nugent, Zoann; Blanchard, James F (15 March 2011). “5-Aminosalicylate Is Not Chemoprophylactic for Colorectal Cancer in IBD: A Population Based Study”. The American Journal of Gastroenterology. 106 (4): 731–736. doi:10.1038/ajg.2011.50.
  9. Ghouri, Yezaz A; Richards, David M; Rahimi, Erik F; Krill, Joseph T; Jelinek, Katherine A; DuPont, Andrew W (9 December 2014). “Systematic review of randomized controlled trials of probiotics, prebiotics, and synbiotics in inflammatory bowel disease”. Clin Exp Gastroenterol. pp. 473–487. doi:10.2147/CEG.S27530. Retrieved 17 May 2016.