Nourishment for mammalian infants in the first few months of life comes only in the form of milk, which essentially consists of an array of proteins, fats, vitamins, minerals and carbohydrates composed of lactose and other important oligosaccharides. However, in many individuals the tolerance for this kind of food is seen to decrease in adulthood. Lactose intolerance is an age-old clinical condition which has been extensively analysed scientifically; herein the characteristic signs and symptoms of pain, abdominal distention, flatulence, and diarrhea occur after lactose consumption. This disaccharide, present in milk and dairy products, is hydrolysed into glucose and galactose by lactase enzyme thus requiring lactase activity in the small intestinal brush border for its absorption.
The term hypolactasia refers to the deficiency of the lactase enzyme; this in turn results in lactose malabsorption, defined as an inefficient digestion of the disaccharide, which can perpetuate lactose intolerance, the clinical condition defined by the presence of gastrointestinal symptoms due to lactose malabsorption.