The amount of beta-glucan fiber in just a dusting of nutritional yeast each day may be enough to change the course of our immune response to various pathogens, according to a study that put this substance to the test in a randomized, double-blind, placebo-controlled trial for the prevention of common childhood illnesses. The findings reflect an understanding of immunity that began in 1989, when the late Charles Janeway gave a presentation that revolutionized our understanding of the immune system. Janeway had correctly theorized and described the workings of the innate immune system. He proposed that the way our immune cells discriminate between self and “nonself”—that is, our own cells versus invading microbes—may arise from pattern recognition receptors. In other words, he proposed that we’re born with the ability to “recognize patterns of microbial structure.” This is where nutritional yeast—a type of single-celled fungus—comes into play. There’s a unique component of …