This post on the Nutrition Data blog tells us that the probiotics (the good bacteria in yogurt) prevent the flu and cold.
This post seems to focus on the “probiotic supplements or placebo pills”, and says that in a recent study, kids who took these supplements “had about half as many fevers, coughs, and runny noses, took fewer prescriptions and missed fewer days of school.”
Works for adults, too, and of course it doesn’t need to be in pill form. Yogurt works.
This is good news, because I refuse to get the flu shot.