lactose intolerance
Meaning of lactose intolerance: Lactose intolerance results from insufficient lactase enzyme, leading to digestive symptoms after consuming milk or other dairy products.
Definition of lactose intolerance
Lactose intolerance is the reduced ability to digest lactose, the main sugar found in milk and other dairy products, because the small intestine does not produce enough of the enzyme lactase needed to break it down. Undigested lactose then passes into the lower digestive tract, where it can be fermented by bacteria and draw in fluid.
This process commonly produces bloating, gas, abdominal cramping, and diarrhea after consuming dairy products, with the timing and severity depending on how much lactose was consumed and how little lactase activity remains. Lactase production normally declines gradually after childhood in much of the world's population, which is why lactose intolerance often becomes noticeable in adolescence or adulthood.
Lactose intolerance is distinct from a milk allergy, which involves the immune system reacting to milk protein rather than a digestive enzyme deficiency, and the two conditions can produce different symptoms and require different management.
Used in a sentence
The patient's recurrent bloating and diarrhea after consuming dairy products prompted evaluation for lactose intolerance.
Good to know
Lactose intolerance is distinct from a milk protein allergy, since it reflects a digestive enzyme deficiency rather than an immune reaction, and the two conditions are evaluated differently.
Word origin
Where “lactose intolerance” comes from
Formed from Latin lac, lactis, meaning milk, the root of lactose, combined with intolerance, from Latin in-, meaning not, and tolerare, meaning to bear or endure.