Start your day with your gut health in mind with Activia Proactive Plain Prebiotic and Probiotic Low Fat Yogurt. Each 32 oz yogurt tub of creamy plain yogurt contains billions of live and active probiotics paired with 3g of prebiotic fiber per serving. Probiotics are the living microorganisms that have been studied and shown to provide specific health benefits, including supporting gut health.* Prebiotics are fibers that feed the good bacteria in your gut.