Streptococcus thermophilus ST-21 withstands stomach acid and arrives in the intestines alive. Once there, it helps keep the gut microbiome balanced and supports regular digestion.
This strain also aids lactose digestion in people who are sensitive to dairy. Take it as a capsule or powder with food. Eating with a meal protects the bacteria during transit through the digestive tract.
No serious interactions are on record. Anyone with a severely weakened immune system, for instance after an organ transplant, should speak with a doctor before using it.