Primal Defense® ULTRA delivers all the benefits of Primal Defense but differs in that it has 13 species of beneficial cultures with the addition of Saccharomyces boulardii, providing a 15 billion live cell count in three capsules per day. Primal Defense® ULTRA is the ultimate broad-spectrum probiotic formula, made to provide 15 billion live cells¹ per daily amount and 13 species of beneficial cultures including soil-based probiotics called Homeostatic® Soil Organisms (HSOs). Probiotics are living microorganisms that play a critical role in maintaining good health. Present in many live foods but destroyed by heat processing, live probiotic cultures populate the intestinal tract where they play a positive role in digestive and immune system health.† All organs and systems rely on the health of the digestive tract. Proper digestion is essential for the body to absorb and utilize the nutrients it needs. In addition, 75 percent of the cells are necessary for the immune system to function effectively are connected to the gastrointestinal tract.