how does lactose intolerance work and why do only certain people have it
In: Biology
Most mammals naturally stop producing the enzymes that allow them to digest lactose (the sugar in milk) after they leave the infancy stage of their development. Humans however have developed a mutation that allows them to digest it into adulthood at least 3 times. Once in Northern Europe, once in the Central Asian Steppes, and once in Sub Saharan Africa. But that said something like 75% of the global human population is lactose intolerant since most people are from phenotype groups that do not have the mutation.
If you do not have the mutation then the lactose passes through your digestive tract without being broken down and it is intact when it gets to your lower intestines and the bacteria that lives there can consume it. Their waste from doing this will cause you to have a lot of gas, and can cause you to have diarrhea.
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