Laktoz

Laktoz, or lactose, is a disaccharide composed of glucose and galactose. It occurs naturally in milk and dairy products and is a major carbohydrate in mammalian milk. In humans, the enzyme lactase, produced in the small intestine, cleaves lactose into glucose and galactose for absorption. Lactase activity often declines after weaning in many populations, leading to lactose maldigestion. When undigested lactose reaches the colon, gut bacteria ferment it, producing gas and short-chain fatty acids that can cause bloating, cramps, and diarrhea. Lactose intolerance is the set of symptoms arising from this process and is distinct from a milk allergy, which involves immune reactions to milk proteins.

Most dairy products vary in lactose content. Fermented dairy such as yogurt and many aged cheeses may have lower lactose levels because bacteria break it down or because lactose is removed with whey. Lactose-free products are made by adding lactase to milk or by using lactose-free ingredients for foods and drugs.

In populations with a long history of dairy farming, lactase persistence into adulthood is common; in other populations, lactase activity often declines with age. Genetic variation near the LCT gene and regulatory elements influences this trait.

People with lactose intolerance can manage symptoms by moderate lactose consumption, choosing lactose-free options, consuming lactose with meals, or taking lactase enzyme supplements. Adequate calcium and vitamin D intake should be maintained from non-dairy sources if dairy is limited.

Diagnosis can be supported by a hydrogen breath test or genetic testing, and differential diagnoses may include secondary lactose intolerance due to gastrointestinal conditions.