Immunity Boost

    what is the relationship between probiotics and the immune system?

    Feb 11, 2021


     Lilly and Stillwell first used the term “probiotics” in 1965 to describe substances secreted by an organism which stimulate the growth [1]. The word “probiotic” was derived from the Greek word and “biotic” means life [2]. 

     What are probiotics?

    The World Health Organization (WHO) defines probiotics as live microorganisms which when administered in adequate amounts provide diverse health benefits to the host [3]

    Various bacteria are used for the preparation of probiotics. These include Escherichia coli, Streptococcus, Bacillus, and Enterococcus. Some fungal strains from Saccharomyces have also been used [4]. 

    Probiotics refer to “good bacteria.” Which improves microbial balance particularly in the gastrointestinal tract and suppresses the growth of potentially pathogenic bacteria in the gut [5].


    Probiotics are usually found in fermented foods. They are also taken as supplements and for most people they are safe.  

    Probiotics and Immune system

    Recently, many reports suggest that certain probiotics strains have potent immunomodulatory activity in various diseases such as allergic asthma, atopic dermatitis, and rheumatoid arthritis [6].
    The experimental finding suggests that probiotics affect innate immunity by improving the mechanism of pathogenic destruction [7]. The efficacy of probiotics is different according to the type of strains and the number of doses.
    These regulate the immune response of the host’s body and help fight many diseases [8]. 

    The role of the Gastrointestinal Tract 

    One key player in immune health is the gut, a part of the body that is constantly exposed to toxins and foreign substances [9]. Almost 70% of the immune system is located in the gut. We don’t enter the eaten food directly in the body’s bloodstream. First, it is processed in the gut and then it enters the bloodstream.
    Our body is made up of trillion bacteria, and yeasts. Our gut alone contains at least 1000 different species of bacteria, collectively known as intestinal flora. 

    How probiotics help in modulating immune response

    Upon oral administration, it interacts with the intestinal epithelial cells (IECs) associated with lamina propria through Toll-like receptors. This process induces different cytokines [10].
    IECs produce Macrophage chemoattractant protein 1, which sends signals to other immune cells and leads to the activation of T cells, specifically T cells that regulate the release of Interleukin-10 (IL-10)[11, 12]. IL-10 limits host response to pathogens thereby preventing damage to host cells and maintaining normal tissue homeostasis [13].
    Probiotics also maintain the intestinal barrier by an increase of mucins, Goblet, and Paneth cells.
    Macrophages and Dendritic cells (DC) play an important part in innate immune response without inducing an inflammatory response. However, a slight increase in the cellularity of lamina propria can also be observed.
    Health benefits of Probiotics:

    Results from evidence-based studies suggest that probiotics are effective to control the diseases including infectious diarrhea, antibiotic-associated diarrhea, atopic disease, irritable bowel disease, and ulcerative colitis.
    • Several studies suggest that probiotic use reduces the risk of antibiotic-associated diarrhea by 42 % [14].  
    • Probiotics reduced the risk of traveler’s diarrhea by 8%. 
    • A study suggests that eczema symptoms improved in infants who are fed with probiotic-supplemented milk compared to infants not fed with probiotics [15].
    • Probiotics also help fight anxiety and other mental illness. 

    1. Lilly, D. and R.J.S. Stillwell, Growth promoting factors produced by probiotics. 1965. 147: p. 747-8.
    2. Reid, G., et al., Potential uses of probiotics in clinical practice. 2003. 16(4): p. 658-672.
    3. Health, W.H.O.J.P.i.F., N. Properties, and G.f. Evaluation, Food, and Agriculture Organization of the United Nations. (2001) Report of a Joint FAO/WHO expert consultation of evaluations of health and nutritional properties of probiotics in food including powder milk and live lactic acid bacteria in Cordoba, Argentina.
    4. Gorbach, S.L.J.T.A.j.o.g., Probiotics, and gastrointestinal health. 2000. 95(1): p. S2-S4.
    5. Williams, N.T.J.A.J.o.H.-S.P., Probiotics. 2010. 67(6): p. 449-458.
    6. Kang, H.-J., S.-H.J.J.o.n.s. Im, and vitaminology, Probiotics as an immune modulator. 2015. 61(Supplement): p. S103-S105.
    7. Gourbeyre, P., S. Denery, and M.J.J.o.l.b. Bodinier, Probiotics, prebiotics, and synbiotics: impact on the gut immune system and allergic reactions. 2011. 89(5): p. 685-695.
    8. Yan, F., and D.J.C.o.i.g. Polk, Probiotics, and immune health. 2011. 27(6): p. 496.
    9. Georgieva, M., K. Georgiev, and P. Dobromirov, Probiotics, and Immunity, in Immunopathology and Immunomodulation. 2015, IntechOpen.
    10. Perdigon, G., et al., Symposium: probiotic bacteria for humans: clinical systems for evaluation of effectiveness. 1995. 78: p. 1597-606.
    11. Galdeano, C.M., et al., Beneficial effects of probiotic consumption on the immune system. 2019. 74(2): p. 115-124.
    12. Herich, R., and M.J.V.M.-P.-. Levkut, Lactic acid bacteria, probiotics, and immune system. 2002. 47(6): p. 169-180.
    13. Iyer, S.S., and G.J.C.R.i.I. Cheng, Role of interleukin 10 transcriptional regulation in inflammation and autoimmune disease. 2012. 32(1).
    14. Hempel, S., et al., Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysis. 2012. 307(18): p. 1959-1969.
    15. Isolauri, E., et al., Probiotics in the management of atopic eczema. 2000. 30(11): p. 1605-1610.