What causes lactose intolerance?

Lactose intolerance occurs due to an insufficient production of the lactase enzyme, which is necessary for the digestion of lactose, the sugar found in milk and dairy products. When lactase levels are low, the body struggles to break down lactose, leading to gastrointestinal symptoms such as bloating, gas, diarrhea, and cramps after consuming dairy.

The production of lactase typically decreases after weaning, which is a normal process for many individuals, especially those who do not continue to consume significant amounts of dairy throughout their lives. This decreased lactase production means that, for individuals who are lactose intolerant, even small amounts of lactose can trigger symptoms.

While some people may have allergies related to dairy products, such as a milk allergy (which involves the immune system), this is distinct from lactose intolerance and does not relate to an enzyme deficiency. Similarly, high dairy consumption would not cause lactose intolerance but could exacerbate symptoms in those who are already affected due to insufficient lactase production. Additionally, excess production of lactase would alleviate, not cause, symptoms of lactose intolerance.