Lactose is a sugar, which is mainly found in dairy products and is also known as milk sugar. Most people know someone that can only consume a limited amount of milk because of an allergy. Often this is because they cannot tolerate lactose very well; lactose intolerance. As a baby, lactose can (usually) be handled very well, and milk is especially needed. As we age, it is often the case that the tolerance for lactose becomes less and less and symptoms like abdominal pain or nausea caused by reactions in the intestines start to come more regularly. Research has shown that adults originally are lactose intolerant because they can not be digested. Population
There is a specific enzyme which ensures that lactose is degraded. The name of this enzyme is lactase-phlorizin, also referred to as lactase. Adults usually do not make this enzyme anymore, then they have lactose intolerance; lactose cannot be broken down. Especially in the European population, the number of adults that are still producing the enzyme is high and so the number of adults with lactose intolerance is low. Having lactose intolerance is genetically transmissible, that is to say, that it is indicated in the genes whether the enzyme is still produced in adulthood. It may then be passed on to the next generation. Positive selection in European populations is seen predominantly in a diet with increased use of dairy products, which is the main nutritional group that serves as a source of lactose. Because there are (especially in Europe) so many people who do not have lactose intolerance, the question arises as to whether it is only one gene which regulates it, or that there are multiple genes co-operating in order to ensure that the lactose is broken down. European populations are just about the only group that often by natural selection or lactose as adults can degrade. For example, in Asian countries is lactose intolerance very common, there is only a small percentage of adults who are able to break down lactose.
Lactose is found in many more products than just milk or dairy. In some medications, lactose is used as filler. These are quantities that someone with lactose intolerance will not be bothered by, according to the Nutrition Center. In addition, it is also found in many foods where milk or milk powder has been processed. This is always stated on the label. Someone with lactose intolerance can best go to a dietician to get good advice on how much lactose can still be consumed and what kind of products can best be avoided. It is often not necessary to avoid lactose completely. The reactions usually occur by intake of a certain amount of lactose.