What causes lactose intolerance?

Answer 1

lactose intolerance is caused by reduced or absent activity of lactase that prevents the splitting of lactose. it also occures when the small intestine does not produce enough enzyme called lactase. your body needs lactase to break down, or digest lactose.

Answer 2

Lactose intolerance is caused by the normal maturation process in mammals. Infant mammals produce lactase, an enzyme that breaks down lactose, the sugar in milk. Infants need to produce this enzyme, but mammals who are weaned do not. In the vast majority of mammals, the expression of the gene that controls the production of lactase is down-regulated, or turned off, after weaning, and genes regulating the production of enzymes that digest appropriate solid food are turned on.

In some populations of humans, mostly of northern European descent, a genetic mutation occurred between 5,000 and 10,000 years ago that allows them to continue producing lactase into adulthood. This mutation may have allowed these populations to survive an ice age or other crop failure event by consuming the milk of other animals. The mutation was passed on to succeeding generations, and consuming the milk of other animals became a cultural norm in those populations.

Lactose intolerance is not a disease or a disorder. No mammal needs to consume milk past infancy, and no non-human animals routinely consume the milk of another species. If you are lactose intolerant, and you're old enough to read this, you don't need treatment. You just need to stop consuming animal milk and products made with animal milk.