What is Progesterone?

Progesterone, the oldest hormone, is about 500 million years old and is vital to all vertebrates: fishes, reptiles, birds and all mammals, including humans. It plays many roles in vertebrates of both sexes, some of which are: regulating blood sugar, developing intelligence, building bones and brain activity. In the higher animals it is involved in reproduction where it is converted by the adrenal glands into cortisone, oestrogen, testosterone and others.

William Allen and George Corner first isolated progesterone in 1934 and proposed the name because of its progestational activity in the pregnant female. An unfortunate name in many ways as it has now come to be regarded as a female sex hormone, it’s many other roles having been forgotten. Unlike oestrogen and testosterone, it does not impart any secondary sexual characteristics.

It was not until 1943 that Russell Marker made progesterone from the plant steroid diosgenin. Originally he used the Mexican wild yam, Dioscorea villosa, but diosgenin has now been found in many plants, including fenugreek and the soya bean. Once it was found that progesterone could be made in bulk, the biochemists started converting it into all the other hormones we use today, cortisone, testosterone, oestrogen and the synthetic progestins (or progestogens). Again causing progesterone to be forgotten.

There is still much confusion in the minds of both the laity and the professions between progesterone on the one hand, and the progestins (or progestogens) and yam creams on the other. Progesterone is made in our body from cholesterol, which is first broken down into pregnenolone and then into progesterone, which in turn can be broken down into the other hormones we need. Some preparations available contain “natural progesterone” which has an identical molecule to that the body makes. The progestins on the other hand have an altered molecular structure and the various so-called “yam creams” contain no progesterone at all. The latter do contain diosgenin, which the body cannot, however, convert into progesterone.

Hormones are chemical messengers and can only work once inside the nucleus of a cell. To get into the nucleus the hormone needs a carrier which is called a receptor. Receptors are very specific, they will only transport the hormone for which they are made. Progesterone receptors will not transport the synthetic progestins into the cell nor can they make use of diosgenin.