For a study, it was determined that probiotics were live microorganisms that boosted the host’s health when given in adequate amounts. When it comes to probiotics, the US Food and Medicine Administration (FDA) required phase I safety practice when the product was intended to be used as a drug. The researchers determined how safe Bifidobacterium animalis subsp lactis (B. lactis) strain BB-12 (BB-12)-supplemented yogurt was when ingested by a healthy group of people taking antibiotics for a respiratory infection for 10 days. The ability of BB-12 to impact the expression of whole blood immunological markers associated with cell activation and inflammatory response was a secondary goal. Following FDA criteria for an Investigational New Drug, a phase I, the double-blinded, randomized controlled process was conducted (IND). For 10 days, 40 individuals were randomly assigned to drink 4 ounces of BB-12-supplemented yogurt or non-supplemented control yogurt. The number of reported adverse events was used to determine the primary outcome, which was safety and tolerability. There were 165 non-serious adverse events reported, with no significant differences between the control and BB-12 groups. B lactis faecal levels were somewhat higher in the BB-12-supplemented group than in the control group. In addition, changes in whole blood expression of genes related to immune cell regulation and activation were found in the BB-12-supplemented group in a limited sample of patients. When ingested by healthy people who also took antibiotics, BB-12-supplemented yogurt was safe and well-tolerated. The practice served as the foundation for future randomized clinical trials looking into the immunomodulatory benefits of BB-12-fortified yogurt in a range of diseases.