Progesterone is one of the naturally occurring steroid hormones which are synthesised in the body from cholesterol. A hormone acts as a messenger that passes information and instructions to various organs and tissues of the body resulting in a specific physiological function.
Progesterone is a precursor to some key hormones including amongst others, the family of Oestrogens (oestradiol, oestrone, and oestriol), and Testosterone. The difference in shape between the steroid hormones is only small, allowing nevertheless, for a surprising diversity of function. Progesterone and oestrogen are the key hormones for female reproduction and testosterone is the principle male hormone. Oestrogen is responsible for the development and maintenance of the female characteristics – breasts, uterus, body hair and shape. Testosterone is responsible for the typical male characteristics including the testes and regulates the production of sperm. However, small amounts of testosterone also play an important role in the health of women, being partly responsible for maintaining a healthy sex drive. Likewise, men synthesize both oestrogen and progesterone in their bodies, although a lot less is produced and as for women, have a role in maintaining bone health.

Unlike oestrogen and testosterone, progesterone is not responsible for any sex characteristics and this fact in part, is why research shows progesterone in many respects is free of side effects and so safe for supplementation. Also, progesterone is produced in the body in milligrams (one thousand milligrams = 1 gram). A woman normally produces approximately 20mg of progesterone per day during ovulation and between 300 - 400mg a day when pregnant! Oestradiol and oestrone are normally produced in micrograms (one thousand micrograms = 1 mg) about 100 – 200 micrograms per day. When a woman is pregnant estriol becomes more dominant and like progesterone is produced by the placenta in milligrams which indicates its safety compared to oestradiol and oestrone.

The population at large could be forgiven for thinking that oestrogen, important a role as it plays, is just about the only hormone to take into consideration when attempting to achieve optimum reproductive and hormonal health. Television, radio programmes and newspaper articles dedicated to ‘providing the facts’ for women regarding gynaecological health, so often fail to do just that. The mention of progesterone is often as some kind of adjunct or is given no mention at all! Instead it may be included in the generic term ‘progestogen’.

The term ‘progestogen’ can be very confusing. The Oxford Concise Colour Medical Dictionary 2007, tells us that a progestogen is “one of a group of naturally occurring or synthetic steroid hormones”. Some authors use the term to indicate synthetic only. Some individuals use the American term ‘progestin’ when referring to synthetic forms of progesterone and sometimes progesterone may be used to include natural and synthetic! Not helpful when trying to understand this important subject. Also, progestogens are not accepted by progesterone receptors - a receptor being a specialized area of a cell membrane that can bind with a specific hormone.

Progesterone has a quite specific molecular structure that is recognised by the body and which cannot be patented. Synthetic forms of progesterone however, have a molecular struct ure that has been altered and although they have an effect on the body, such hormones cannot be processed correctly, which can result in toxicity and even disease. The term ‘Natural Progesterone’ refers to progesterone that can be supplemented in various forms including cream and suppositories. The progesterone in such products is made in a laboratory from plant compounds called Saponins and the resulting natural progesterone has the same chemical structure as the progesterone that our bodies produce and can therefore be readily recognised and processed to contribute to hormonal health when supplemented correctly.