Streptococcus thermophilus, one of the most extensively used probiotics in yogurt and dairy production, is generally considered as safe. Many Streptococcus spp. are known pathogens; however, extensive research has revealed S. thermophilus found in dairy is beneficial for health. In addition, S. thermophilus may relieve lactose intolerance symptoms by breaking down the sugars in milk otherwise difficult to digest.
Some studies have shown S. thermophilus strains may reduce antibiotic-associated diarrhea caused by antibiotics destroying bacteria indiscriminately. Adults that included yogurt containing S. thermophilus while treated with antibiotics experienced lower rates of diarrhea than those that did not include S. thermophilus (12.4% vs. 23.7%).
Ben-Yahia, L., Mayeur, C., Rul, F. et al. Growth advantage of Streptococcus thermophilus over Lactobacillus bulgaricus in vitro and in the gastrointestinal tract of gnotobiotic rats. Beneficial Microbes. 2012. 3(3):211-9. doi: 10.3920/BM2012.0012
Ripudaman S.B., Arena, V.C., Thomas, L. et al. A Randomized Trial of Yogurt for Prevention of Antibiotic-Associated Diarrhea. Digestive Diseases and Sciences. 2003. 48(10): 2077–2082. doi: 10.1023/A:1026155328638