Primal Defense is the only probiotic formula that contains a unique whole food blend with Homeostatic? Soil Organisms (HSOs). The HSOs in Primal Defense are important probiotics you would get in abundance if your food came from soil untouched by pesticides, herbicides and other widely used chemicals. To replenish the valuable probiotics our pasteurized, irradiated and disinfected food no longer provides, Primal Defense includes 12 species of hardy beneficial microorganisms in the form of the HSO Probiotic Blend. Let the unique HSOs in Primal Defense take you to a new level of total health.