Glycine is the amino acid that makes up a third of collagen and gelatin. Here is what the human trials measured for sleep, blood sugar and glutathione, which foods contain the most, the doses researchers used, and what the safety literature records.

What the research supports for eating with Hashimoto's thyroiditis: the nutrients that matter, the foods to limit, why medication timing beats most food rules, and a side-by-side look at gluten-free, the autoimmune protocol, and the bioenergetic approach.

A plain guide to the autoimmune protocol diet: the full elimination food list, what you can eat, how reintroduction works stage by stage, what the Hashimoto's and IBD pilot studies found, and where AIP disagrees with the bioenergetic view.

The foods highest in collagen are the parts most people throw away: skin, tendons, cartilage, bone, and the gelatin that cooks out of them. Here is which foods carry the most, how bone broth stacks up against powders, what Ray Peat argued about balancing muscle meat with gelatin, and what the skin, tendon, and muscle trials measured.

Vitamin C is the cofactor two enzymes need to build collagen correctly. Here is what that means in skin, what the human studies found and where their designs are weak, and which foods and cofactors the pathway depends on.