Streptococcus thermophilus is a lactic acid bacterium commonly used as a starter culture in the production of yogurt and other fermented dairy products. Its use to support the small intestines is primarily based on its probiotic potential and its role in improving lactose digestion. There is scientific evidence suggesting that S. thermophilus can survive passage through the gastrointestinal tract and exert beneficial effects within the small intestine, particularly by aiding the breakdown of lactose into simpler sugars, thus alleviating symptoms of lactose intolerance (Vinderola et al., 2017; EFSA Panel, 2010).

Studies have shown that S. thermophilus can temporarily colonize the small intestine and contribute to gut homeostasis by producing lactic acid, which may inhibit the growth of pathogenic bacteria (Guarner et al., 2005). Additionally, there is evidence that S. thermophilus may enhance barrier function and modulate immune responses in the gut, although these effects are less consistently supported compared to its role in lactose digestion (Meynier et al., 2017).

Overall, while S. thermophilus is not as extensively studied as some other probiotics for broader small intestine health, there is moderate scientific validation for its specific benefits, particularly for individuals with lactose intolerance and for supporting a healthy microbiota environment in the small intestine.