Human health effects of lactose consumption as food and drug ingredient.

Lactose is a reducing sugar consisting of galactose and glucose, linked by a beta (1→4) glycosidic bond, considered as an antioxidant due to its alpha-hydroxycabonyl group. Lactose is widely ingested through milk and other unfermented dairy products and is considered to be one of the primary foods. On the other hand, lactose is also considered as one of the most widely used excipient for the development of pharmaceutical formulations. In this sense, lactose has been related with numerous drug-excipient or drug-food pharmacokinetic interactions. Intolerance, maldigestion and malabsorption of carbohydrates are common disorders in clinical practice, lactose-intolerance being the most frequently diagnosed, afflicting 10% of world's population. Four clinical subtypes of lactose intolerance may be distinguished, namely Lactase Deficiency in Premature Infants, Congenital Lactase Deficiency, Adult-type Hypolactasia and Secondary Lactase intolerance. An overview of the main uses of lactose in human nutrition and in pharmaceutical industry and the problems derived from this circumstance is described in this review.