Acid can damage the stomach, so the walls of the stomach have a special lining to protect it. Increases in stomach acidity can damage the protective lining and lead to a peptic ulcer. Bacterial or viral inflammation, anxiety, and alcohol can all increases the level of stomach acid. The digestive process continues in the small intestine, the major site of digestion and absorption of food. Digestive enzymes assist in the breakdown of food particles to make them smaller for absorption.
Lactose intolerance occurs due to an absence or deficiency of the intestinal enzyme lactase.
When lactose, the main carbohydrate component of milk, is not digested, diarrhea and fluid loss result. In addition, bacteria in the large intestine will metabolize the lactose to produce large quantities of gas which causes bloating and pain. It therefore seems that many of us do not have the ability to digest lactose. Most digestion is completed in the small intestine. While the idea of microorganisms flourishing in the body may not be that appealing, these intestinal bacteria, called the intestinal flora, have an important role in the body.