Immunologic effects of yogurt

Many investigators have studied the therapeutic and preventive effects of y ogurt and lactic acid bacteria, which are commonly used in yogurt productio n, on diseases such as cancer, infection, gastrointestinal disorders, and a sthma. Because the immune system is an important contributor to all of thes e diseases, an immunostimulatory effect of yogurt has been proposed and inv estigated by using mainly animal models and, occasionally, human subjects. Although the results of these studies, in general, support the notion that yogurt has immunostimulatory effects, problems with study design, lack of a ppropriate controls, inappropriate route of administration, sole use of in vitro indicators of the immune response, and short duration of most of the studies limit the interpretation of the results and the conclusions drawn f rom them. Nevertheless, these studies in tote provide a strong rationale fo r the hypothesis that increased yogurt consumption, particularly in immunoc ompromised populations such as the elderly, may enhance the immune response , which would in turn increase resistance to immune-related diseases. This hypothesis, however, needs to be substantiated by well-designed randomized, double-blind, placebo-controlled human studies of an adequate duration in which several in vivo and in vitro indexes of peripheral and gut-associated immune response are tested.