in Clover Opta Gest Prebiotic Enzyme (Pack of 2) Diet change, age, or stressful situations reduce digestive efficiency resulting in diarrhea and gas. OptaGest is a complete, natural digestive formula of four plant enzymes, plus prebiotic, to assure proper digestion and absorption of nutrients throughout the entire digestive system. Clinically-tested levels of the prebiotic FOS feed the naturally-occurring bacteria that replenish essential enzymes. OptaGest contains NO fillers, sugar, or preservatives.