Yogurt with sufficient amounts (108 bacteria/mL) of S. thermophilus and L. bulgaricus (as is the case in most commercial yogurts) is very well tolerated by lactose “maldigesters”, because it is effectively comparable to taking enzyme supplements with dairy food, due to the bacterial lactase.
Is the bacterial lactase active in the yogurt ?
The bacterial lactase survives the acidic conditions of the stomach, apparently being physically protected within the bacterial cells and facilitated by the buffering capacity of yogurt.
The increasing pH as the yogurt enters the small intestine, and a slower gastrointestinal transit time, allows the bacterial lactase to be active, digesting lactose from yogurt sufficiently well to prevent symptoms in lactose-intolerant people.
Compared with unflavoured yogurts, flavoured yogurts appear to exhibit somewhat reduced lactase activity but are still well tolerated.