Immunomodulatory Role of Milk on Gut Microbiota: Implications for Enhancing Oral Vaccine Efficacy.

Vaccination is one of the most effective health interventions, sparing an estimated 2-3 million deaths each year. While systemic vaccinations produce strong pathogen-specific humoral and cellular immune responses in the peripheral system, they are often less efficient at establishing protective immunity at mucosal surfaces. Oral vaccinations have the benefit of inducing both systemic and mucosal immunity; nonetheless, they are frequently linked with lower immunogenicity when compared to parenteral vaccines. This variability in response has been related to a variety of factors. However, increasing research points to the gut microbiota as a major, modifiable predictor of vaccine responsiveness. Specific microbial profiles have been associated with increased antibody production and vaccination effectiveness. Milk, a natural source of bioactive substances with prebiotic qualities, has been found to maintain beneficial gut microbiota and may help improve immunological responses to oral vaccination. In this narrative review, we examine the current research on milk and its bioactive compounds in modifying gut microbiota composition, as well as its potential use in increasing oral vaccination efficacy. By applying this knowledge, we intend to address challenges in the development of oral vaccines for more comprehensive and efficient protection.