Children create lactase to process milk (lactose) until around puberty, then they stop creating it. I learned in college that studies have shown that a lot of people of Northern European descent continue to create lactase into adulthood, and thus can continue to break down milk and cheeses without issue.

There is still a percentage of non-European population that can consume lactose into adulthood, and not break it down without any external symptoms.

There are plenty of non-Europeans that can digest lactose. Think middle-easterners and Mediterraneans and their consumption of sheep and goat milk. Central and East africans too. The trait has incomplete (variable) penetrance.

Lactose tolerance is estimated at 30-45 percent.. So it's a substantial non-European population. The intolerance is heavily skewed toward East and South Asia -- though a lot of South Asians consume milk and paneer.

Wow, what's your damage, man? When did I ever claim to be "smart"?

Let's say this is my area of expertise. I am informing you that lactose intolerance is due to a deficiency in the enzyme lactase, a typically endogenously (by your bodies' cells) produced enzyme. It is therefore not a component of the gut biome. The proteins in your body can affect the gut microbiome, just as the micro and macro structure of your organs can, but they are not part of the biome.

Lactase is present in all normal human infants, since all healthy human babies are capable of digesting breast milk. Lactase expression starts trailing off in toddler-hood. Some populations apparently developed a mutation that causes lactase to persist. One group are northern European/Scandinavians. But there are also other groups such as certain Africans and Meds/Middle Easterners that have lactase persistence (Mediterranean and Middle Eastern people have a long history of consuming sheep and goat milk). The interesting thing is that there are multiple, independent mutations.

The cause for lactase persistence has a number of hypothesis, such as the consumption hypothesis. But these are speculation.

There is no cure for lactase deficiency. The most common "treatment" is oral enzyme replacement. This is known as Lactaid and Lactrase. Lactrase seems to work better for symptoms in most people, but response is variable.

Are you alright, Sam?

You seem to be posting a lot of pretty hostile posts to this thread.