⏱ 3 min read
Hormones seem like an endless catalog of disparate molecules, but many share a surprisingly common origin. The most elegant case is that of the steroid hormones: all of them —from testosterone and estrogens to cortisol and aldosterone— derive from a single raw material, cholesterol. The first step, the one that sets the pace of the entire production line, converts cholesterol into pregnenolone inside the mitochondrion; from there, a tree of enzymes branches toward each final hormone according to the tissue and the need.
The second major tree is that of the thyroid hormones, which start not from cholesterol but from the amino acid tyrosine bound to iodine: the thyroid assembles T4 and T3 by attaching iodine atoms to tyrosine residues. This explains why iodine is a critical nutrient and why its deficiency causes goiter and hypothyroidism: without the mineral precursor, the gland cannot build the hormone.
Cholesterol's bad reputation hides the fact that it is the cornerstone of hormonal physiology and of the membrane of every cell. Without cholesterol there would be no sex hormones, no cortisol to respond to stress, no vitamin D, and no bile salts. The body considers it so essential that it makes it itself in the liver, regulating its production with relative independence from diet. In the context of precursors, cholesterol is the trunk from which entire hormonal branches sprout.
Pregnenolone and DHEA sit at the top of the steroid tree, before the pathway specializes, and for this reason they are sometimes marketed as supplements on the idea that the body will convert them into whichever hormones it needs. The reality is more delicate: they are hormones in themselves, with effects of their own, and supplementing them can alter the balance of androgens and estrogens in ways that are hard to predict. Their use should be reserved for specific situations and under medical supervision, with lab tests along the way.
The precursor logic runs through the entire endocrine system. Vitamin D is a prohormone that is activated in the liver and kidney; testosterone is converted in target tissues into dihydrotestosterone (more potent) or into estradiol; thyroid T4 is largely a reservoir that is converted into the more active T3 in tissues. Understanding hormones is, in large part, understanding this chain of precursors and successive activations.
Educational information, not medical advice.