Similac® Probiotic Tri-Blend Product Specifications

Probiotic Blend: Bifidobacterium lactis (BB-12®), Bifidobacterium infantis (BB-02), Streptococcus thermophilus (TH-4®)







Intended for use in infants to support the health of the developing GI tract



How Supplied



• 1 sachet (0.5 g) contains 1 billion CFU per sachet (guaranteed potency through date on box when stored as directed)



Dose & Administration



Dose: One sachet daily 

Administration: Orally or Enterally



Storage/Handling/ Preparation




  • Store unopened sachets at or below room temperature (25°C [77°F]). Product is stable at room temperature. 
  • Use by date on the bottom of the carton. 


  1. Pour 3 mL breast milk, donor milk, infant formula, sterile water, or 5% glucose water (commercially sterile) into disposable mixing container. If warmed, do not exceed 37°C (98.6°F). 
  2. Gently shake sachet to ensure contents are settled to bottom.
  3. To open sachet, tear top off completely along perforation. 
  4. Slowly add 1 sachet of Similac Probiotic Tri-Blend powder to mixing container. 
  5. Using a single-use oral syringe, gently swirl until uniformly distributed.
  6. Draw up contents from container into syringe. 
  7. Administer with oral syringe; mixed product also flows easily through feeding tube. 
  8. Administer mixed product within 60 minutes or may be stored refrigerated (below 40 degrees F) for up to 3 hours prior to administration. If sediment occurs, gently shake to resuspend into solution before administering.
Mechanism of Action

Probiotics mediate their biological effects through an array of strain-specific mechanisms (Plaza-Diaz et al, 2019). Major modes of action include: (1) colonization and normalization of perturbed intestinal microbial communities; (2) competitive exclusion of pathogens and bacteriocin production; (3) modulation of fecal enzymatic activities associated with the metabolism of biliary salts and inactivation of carcinogens and other xenobiotics; and (4) production of short- and branched-chain fatty acids. These activities can have systemic effects on host physiology. For example, in addition to reducing colonic luminal pH, short-chain fatty acids (SCFAs), namely acetate, propionate, and butyrate, act as signaling molecules and serve as energy substrates (Koh et al, 2016). SCFAs directly activate G-coupled receptors located throughout the body to mediate host metabolism (eg, gut motility, satiety, insulin activity, gluconeogenesis, and lipid storage) and inflammation (Koh et al, 2016). Individually, butyrate serves as an important source of energy for colonic epithelial cells, and propionate is converted to glucose via intestinal gluconeogenesis (Koh et al, 2016). 

The exact mechanisms of action for probiotics are likely mediated in part through the fermentation of prebiotics, such as human milk oligosaccharides, to lactate and acetate. These acids reduce colonic pH, which encourages a more favorable balance of intestinal bacteria (Henrick et al, 2018). Furthermore, acetate, a major fermentation product that is common to all species of bifidobacteria, has been shown to improve intestinal barrier function in an animal model (Fukuda et al, 2011). 

Research studies using individual strains of B lactis, B infantis, and S thermophilus suggest that these species may confer beneficial physiological effects on infants. A clinical study in healthy, formula-fed, term infants showed that Bifidobacterium lactis BB-12 promoted immune function by enhancing antibody response (Holscher et al, 2012). Furthermore, preclinical studies suggest that Bifidobacterium infantis, a functionally important bifidobacteria species found in breastfed infants (Sela & Mills, 2010), dampens inflammation in cell culture (Wickramasinghe et al, 2015; Meng et al, 2016) and in an animal (Elian et al, 2014) models. Finally, Streptococcus thermophilus, a species well known for its use in yogurt manufacture, may also contribute to infant health via the production of folate. Indeed, the TH-4 strain has been shown in vitro to produce large amounts of folate (Albuquerque et al, 2017), a nutrient that may be limiting for certain infants (Oncel et al, 2012).


Bifidobacterium lactis BB-12 has been used globally in infant formulas, dietary supplements, and fermented milk products for over 25 years. This strain has been described in more than 300 scientific publications of which include at least 130 human clinical studies making it among the world’s most-studied probiotics (Jungersen et al, 2014). BB-12 displays an array of in vitro properties that make it highly suitable as a probiotic such as tolerance to gastric and bile acids, secretion of bile salt hydrolase, adhesion to intestinal mucus, strengthening intestinal barrier function, and interacting with the immune system (Jungersen et al, 2014). A double-blind, placebo-controlled, randomized clinical study in healthy 4- to 10-month-old infants attending daycare (n = 73) showed that supplementation of standard infant formula with 1 x 107 CFU of B lactis BB-12/g powder for 12 weeks supported immune function and resulted in less absences from childcare than infants who received non-supplemented control formula (n = 60; Weizman et al, 2005). In a long-term, prospective, double-blind, randomized, placebo-controlled feeding study (Saavedra et al, 2004), healthy infants (3 to 24 months of age) were supplemented with either 1 x 106 or 1 x 10CFU each of B lactis (BB-12) and Streptococcus thermophilus (TH-4) per g infant formula powder. Infants who received either the high (n = 39) or low (n = 39) dose of probiotics experienced a lower frequency of parent- and caregiver-reported colic or irritability (P < 0.001) than those who received a probiotic-free control (n = 40). 

Bifidobacterium infantis BB-02, which originated from the infant intestine, has not been clinically studied in healthy term infants.



Comparison with current formulary alternative



No current comparable product






  • Use as directed


Albuquerque MAC, Bedani R, LeBlanc JG: Passion fruit by-product and fructooligosaccharides stimulate the growth and folate production by starter and probiotic cultures in fermented soymilk. Int J Food Microbiol. 2017;261:35-41.  

Elian SDA, Souza ELS, Vieira AT, et al: Bifidobacterium longum subsp. infantis BB-02 attenuates acute murine experimental model of inflammatory bowel disease. Beneficial Microbes. 2015;6:277-286. 

Fukuda S, Toh H, Hase K, et al: Bifidobacteria can protect from enteropathogenic infection through production of acetate. Nature. 2011;469:543-549.  

Henrick BM, Hutton AA, Palumbo MC, et al: Elevated fecal pH indicates a profound change in the breastfed infant gut microbiome due to reduction of Bifidobacterium over the past century. mSphere. 2018;3:e00041-18. 

Holscher HD, Czerkies LA, Cekola P, et al: Bifidobacterium lactis Bb12 enhances intestinal antibody response in formula-fed infants: A randomized, double-blind, controlled trial. J Parenteral Enteral Nutr. 2012;106S-117S.  

Jungersen M, Wind A, Johansen E, et al: The science behind the probiotic strain Bifidobacterium animalis subsp. lactis BB-12®. Microorganisms. 2014;2:92-110. 

Koh A, De Vadder F, Kovatcheva-Datchary P, et al: From dietary fiber to host physiology: short chain fatty acids as key bacterial metabolites. Cell. 2016;165:1332-1345.  

Meng D, Zhu W, Ganguli K, et al: Anti-inflammatory effects of Bifidobacterium longum subsp infantis secretions on fetal human enterocytes are mediated by TLR-4 receptors. Am J Physiol Gastrointest Liver Physiol. 2016;311:G744-G753. 

Oncel MY, Ozdemir R, Erdeve O, et al: Influence of maternal cigarette smoking during pregnancy on neonatal serum folate levels. Eur J Nutr. 2012;51:385-387.  

Plaza-Diaz J, Ruiz-Ojeda FJ, Gil-Campos M, et al: Mechanisms of action of probiotics. Adv Nutr. 2019;10:S49-S66. 

Saavedra JM, Abi-Hanna A, Moore N, et al: Long-term consumption of infant formulas containing live probiotic bacteria: tolerance and safety. Am J Clin Nutr. 2004;79:261-267.  

Sela DA, Mills DA: Nursing our microbiota: molecular linkages between bifidobacterial and milk oligosaccharides. Trends Microbiol. 2010;18:298-307. 

Weizman Z, Asli G, Alsheikh A: Effect of a probiotic infant formula on infections in child care centers: comparison of two probiotic agents. Pediatr. 2005;115:5-9.  

Wickramasinghe S, Pacheco AR, Lemay DG, et al: Bifidobacteria grown on human milk oligosaccharides downregulate the expression of inflammation-related genes in Caco-2 cells. BMC Microbiol. 2015;15:172.