Glycine might be the most deficient nutrient in the modern diet and nobody talks about it. It's the most abundant amino acid in connective tissue. It repairs the tight junctions in the gut wall. When those break down, that's leaky gut. We used to get it from eating the whole animal. Bones, skin, cartilage, organ meat. Now we eat muscle meat only and wonder why our guts are falling apart. 3-5g daily in water or broth. Cheapest supplement going. Highest return I've found