A waxy, fat like substance that travels throughout the body in carrier lipoproteins (HDL, LDL, and VLDL); a precursor to steroid hormones and bile salts. May be elevated due to poor thyroid function, insulin resistance, blood glucose dysregulation, magnesium deficiency, dehydration, kidney disease, familial hypercholesterolemia. May be decreased due to liver dysfunction, oxidative stress, inflammation, malabsorption, anaemia.