Natural Factors Lactase Enzyme - Helps prevent the symptoms of lactose intolerance and assists in the digestion of dairy products. Lactose intolerance is the inability to digest lactose (milk sugar), caused by the lack of lactase, the enzyme responsible for breaking down lactose in the digestive tract. As it is an enzyme that works directly on lactose present in food being ingested, the capsules must be taken each time lactose-containing foods are consumed as the enzyme only works on the food just consumed. Lactase has no lasting effect beyond the meal with which it is taken.