What is a leaky gut?
Your gut helps your body absorb fluids and nutrients, digests your food, and houses billions of friendly gut microbes.
It's also selective to what it allows past its barrier. Your intestinal tract purposefully keeps some things from being absorbed, so they pass right on through to the other end to be eliminated as waste. You don't want to absorb many harmful microbes or toxins into your body, right?
Once the essential nutrients are absorbed by the cells of the gut lining, they are carried by the blood and lymph to your liver, and then around to the rest of your body; this is so that all your cells, all the way to your toenails, get the nutrition they need to be healthy and grow.