Sweeteners work in a couple ways. The first is that it is a sugar molecule that can't be split into glucose, and thus can't be absorbed through the gut. Since the sweetener is not absorbed by the gut it exits in the usual way.
Some of these sugar molecules are digestible by gut microbes, which leads to selection for gut flora that can gain energy from these indigestible sugars. This is what happens to people with lactose intolerance.
The second type are absorbed through the gut and then immediately eliminated by the kidneys. Sugar alcohols act in this way.
Changing the micro-biome has all kinds of complex effects. It isn't straightforward what the interactions between the micro-biome and the human immune system.
Sweeteners work in a couple ways. The first is that it is a sugar molecule that can't be split into glucose, and thus can't be absorbed through the gut. Since the sweetener is not absorbed by the gut it exits in the usual way.
Some of these sugar molecules are digestible by gut microbes, which leads to selection for gut flora that can gain energy from these indigestible sugars. This is what happens to people with lactose intolerance.
The second type are absorbed through the gut and then immediately eliminated by the kidneys. Sugar alcohols act in this way.
Changing the micro-biome has all kinds of complex effects. It isn't straightforward what the interactions between the micro-biome and the human immune system.