Results of a six-month UC Davis School of Medicine study link the consumption of a certain kind of yogurt to an increased production of gamma interferon, associated with bolstering the immune defense system. The recent study of 68 adults, ages 20-40, showed that the group that consumed two cups of live-and-active culture yogurt every day over a four-month period produced four times as much gamma interferon as the two other test groups, says allergist and principal investigator Dr. Georges M. Halpern. One group ate no yogurt and the other group received heat-treated yogurt. The yogurt with the living organisms contained Lactobacillus bulgaricus and Streptococcus thermophilus, used to ferment pasteurized milk into yogurt. The research was published in the International Journal of Immunotherapy. "Further research is under way to determine if those who consume live-and-active culture yogurt daily have fewer upper respiratory infections, including the common cold, than those who eat no yogurt or heat-treated yogurt," Halpern says.