As defined by the International Scientific Association for Probiotics and Prebiotics, probiotics are live microorganisms that, when consumed in adequate amounts, provide a health benefit to the host. 1 When probiotics are taken orally through foods or supplements, they must survive GI transit (stomach pH, bile acid, and digestive enzymes), reach the colon, and adhere to colon cells to exert health benefits and barrier effects against pathogenic microorganisms.2 Probiotics can generate lactic acid and butyrate by fermenting prebiotics and fermentable soluble fibers that provide health benefits. Bifidobacteria and lactobacilli are the two most researched probiotics, demonstrating evidence for their various health benefits. 3 Probiotic doses are listed as colony-forming units (CFUs), which means the number of live strains in each dose. There are other ways to count probiotic bacteria, like active fluorescent units (AFU), an advanced and more precise method for cell enumeration. CFU or AFU tells you how many live microorganisms are in each serving dose through the expiration date.

Major Health Benefits

Some health benefits of probiotics are relatively common (e.g., improved digestion). In contrast, others are very specific (e.g., help with stress and anxiety). Thus, no probiotic strain can be expected to provide all the suggested health benefits; different probiotic strains may have myriad benefits.

Common Forms

Bifidobacteria are naturally found in the colon since they prefer and survive better in an environment without oxygen but can be grown by culture for use in dietary supplements.


Bifidobacterium lactis HN019

B. lactis HN019 has been consumed in dairy foods for decades and is well-studied for its probiotic properties in more than 100 scientific publications. It was clinically tested to improve gut transit time and functional GI symptoms, including regurgitation, abdominal pain, nausea, gurgling, constipation, irregular bowel movements, and flatulence. 4 This strain was also clinically tested to enhance cellular immunity in the elderly by increasing immune cells and activity. 5,6


Lactobacillus is one of the most important and dominant beneficial bacteria found in the GI tract and the urogenital tract in humans.


Lactobacillus acidophilus GLA-14 and Lactobacillus rhamnosus HN001

The combination of L. acidophilus GLA-14 and L. rhamnosus HN001, and lactoferrin supports healthy bacterial vaginal colonization and has demonstrated improvements in women’s health conditions such as bacterial vaginosis and vulvovaginal candidiasis. 7,8 These probiotics act through two main mechanisms: the inhibition of pathogens’ adhesion to the vaginal epithelium and the production of antimicrobial compounds like hydrogen peroxide, lactic acid, and bacteriocins. 9


Lacticaseibacillus paracasei Lpc-37

L. paracasei Lpc-37 is a common inhabitant of the human intestinal tract. 10 L. paracasei strains are also found naturally in fermented vegetables, milk, and meat. L. paracasei Lpc-37 has been studied in multiple clinical trials and has a long history of safe use. This probiotic beneficially alters the microbiota composition in the gut and increases the concentration of short-chain fatty acids. 11 It was also shown to benefit the response to stress and improve mood and well-being with higher doses. 10


Lacticaseibacillus rhamnosus GG

L. rhamnosus GG has been shown clinically to efficiently colonize the human gut. 12 This probiotic has been used in more than 250 clinical studies. Clinical research found that L. rhamnosus GG helps relieve symptoms of irritable bowel syndrome, among many other benefits. 13



It is recommended to consult with a doctor before taking probiotic supplements for infants, children, and adults with weakened immune system or short bowel syndrome. 14



  1. Hill, C., Guarner, F., Reid, G. et al. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol 11, 506–514 (2014).
  2. Macfarlane GT, Cummings JH. Probiotics and prebiotics: can regulating the activities of intestinal bacteria benefit health? West J Med. 1999 Sep;171(3):187-91.
  3. Saulnier DM, Spinler JK, Gibson GR, Versalovic J. Mechanisms of probiosis and prebiosis: considerations for enhanced functional foods. Curr Opin Biotechnol.2009 Apr;20(2):135-41.
  4. Waller PA, Gopal PK, Leyer GJ, et al. Dose-response effect of Bifidobacterium lactis HN019 on whole gut transit time and functional gastrointestinal symptoms in adults. Scandinavian J Gastroenterology. 2011;46:1057-1064.
  5. Gill HS, Rutherfurd KJ, Cross ML. Dietary probiotic supplementation enhances natural killer cell activity in the elderly: an investigation of age-related immunological changes. J Clin Immunol. 2001 Jul;21(4):264-71.
  6. Gill HS, Rutherfurd KJ, Cross ML, Gopal PK. Enhancement of immunity in the elderly by dietary supplementation with the probiotic Bifidobacterium lactis HN019. Am J Clin Nutr. 2001 Dec;74(6):833-9.
  7. Russo R, Superti F, Karadja E, De Seta F. Randomised clinical trial in women with Recurrent Vulvovaginal Candidiasis: Efficacy of probiotics and lactoferrin as maintenance treatment. Mycoses. 2019 Apr;62(4):328-335.
  8. Russo R, Karadja E, De Seta F. Evidence-based mixture containing Lactobacillus strains and lactoferrin to prevent recurrent bacterial vaginosis: a double-blind, placebo-controlled, randomised clinical trial. Benef Microbes. 2019;10(1):19-26.
  9. Bertuccini L, Russo R, Iosi F, Superti F. Lactobacilli and lactoferrin: biotherapeutic effects for vaginal health. J Funct Foods. 2018;45:86‐94.
  10. Patterson E, Griffin SM, Ibarra A, et al. Lacticaseibacillus paracasei Lpc-37® improves psychological and physiological markers of stress and anxiety in healthy adults: a randomized, double-blind, placebo-controlled, and parallel clinical trial (the Sisu study). Neurobiol Stress. 2020 Nov 24;13:100277.
  11. Forssten et al. Influence of a Probiotic Milk Drink, Containing Lactobacillus Paracasei Lpc-37, on Immune Function and Gut Microbiota in Elderly Subjects. Eur. J. Food Res. Rev. 2011;1(3): 159-172
  12. Saxelin, M. Ahokas & S. Salminen (1993) Dose Response on the Faecal Colonisation of Lactobacillus Strain GG Administered in Two Different Formulations, Microbial Ecology in Health and Disease, 6:3, 119-122
  13. Pedersen N, Andersen NN, Végh Z, Jensen L, Ankersen DV, Felding M, Simonsen MH, Burisch J, Munkholm P. Ehealth: low FODMAP diet vs Lactobacillus rhamnosus GG in irritable bowel syndrome. World J Gastroenterol. 2014 Nov 21;20(43):16215-26.
  14. S. National Library of Medicine. Lactobacillus. MedlinePlus. Feb 15, 2015.