Decreasing your exposure to microbes might have different results depending on what your microbiota was like before the decrease. In order to decrease your exposure to microbes, you want to limit yourself coming in contact with them. Things like not owning any pets, using a lot of hypo-allergenic cleaning supplies, eating a limiting diet, not going out in nature, not traveling to different parts of the world, and all-in-all staying inside closed quarters. You pretty much have to quarantine yourself to the real world in order to completely reduce any exposure to microbes. However, evidence suggests that exposing yourself to the outside world, and getting dirty strengthens your immune system.
