Final answer:
Lactose intolerance develops when the body produces insufficient lactase, leading to digestive problems with dairy consumption. Lactase production typically diminishes with age, but genetic factors allow some populations to maintain lactase production into adulthood. Alternatives like lactose-free products can help manage the condition.
Step-by-step explanation:
Lactose intolerance occurs when the body does not produce enough lactase, the enzyme responsible for digesting lactose, a sugar found in milk and dairy products. This condition can develop as people age because the production of lactase decreases, leading to symptoms such as bloating, cramps, nausea, and vomiting when consuming dairy.
In infants with a deficiency of lactase due to an inborn defect, they experience intolerance to milk which manifests as diarrhea and vomiting. For such cases, lactose-free milk or milk powder alternatives are given.
Some populations, particularly in Europe, have evolved a genetic mutation that allows them to produce lactase into adulthood, giving them the ability to consume milk without issue. This development is thought to be an evolutionary advantage linked to the absorption of vitamin D and the practice of dairy agriculture. In contrast, it is quite common in the Asian population and other groups worldwide to develop lactase deficiency as they grow older, leading to lactose intolerance.
It is possible for some individuals to adapt over time through prebiotic adaptation, where changes in gut microbes can increase tolerance to lactose. Additionally, for those who cannot adapt, alternatives such as lactose-free products or enzymes in the form of tablets can help manage the condition and ensure that essential nutrients are still part of their diet.