Lactase is an enzyme that breaks down lactose, the main sugar exclusively found in the milk of lactating animals. Lactose is found at a concentration of approximately 5% in bovine milk and 7% in human milk. It is a major source of energy for an infant. Lactose is hydrolysed in the small intestine by lactase, causing the breakdown of the glycosidic bonds in the disaccharide, resulting in glucose and galactose molecules. The enzyme lactase is naturally found in the human body; however, its activity naturally reduces after infancy in 75% of the world’s population, resulting in lactose intolerance being common place. In such circumstances lactose is difficult to digest, resulting in excessive fluid and gas build up in the bowels, bloating and cramping. The enzyme lactase tends to be used in formulations containing milk-based ingredients to aid in the breakdown and digestion of these ingredients, helping with the discomfort associated with digestion.
Geissler, C. & Powers, H. eds., 2005. Human Nutrition. 11th Ed. London: Elsevier Churchill Livingstone
Antonio, J., Kalman, D., Stout, J. R., Greenwood, M., Willoughby, D. S. & Haff, G. G. eds., 2008. Essentials of Sports Nutrition and Supplements. USA: Humana Press