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'Natural' Progesterone - why this is not the answer

by Marilyn Glenville, PhD(more info)

listed in women's health, originally published in issue 21 - August 1997

In 1966 Dr Robert Wilson, a New York gynaecologist, wrote a book called Feminine Forever extolling the virtues of oestrogen replacement for women at the menopause. By taking it for the rest of our lives, he declared, we could partake forever of the ‘fountain of youth’ as he described it. Dr Wilson, a charming man, whom I once met, was certainly sincere enough in his desire to help women who experienced difficulties at the menopause. But it was his theories, expounded in this best-selling book, that created the concept of the menopause as a deficiency disease, an illness which could have dire consequences if left untreated. “Women will be emancipated only when the shackles of hormonal deprivation are loosened,” burbled the foreword written by another eminent doctor. The message was that we ignored the prospect of oestrogen replacement at our peril. It had a huge impact on popular health thinking at the time. Dr Wilson got quite carried away by it all, claiming there was ample evidence that the whole course of history has been changed not only by the presence of oestrogen but by its absence. Unstable oestrogen-starved women, he postulated, were a misery to themselves and everyone else, causing, at the extreme, alcoholism, drug addiction, divorce and broken homes. As you can imagine this changed the thinking of many women and doctors for decades. Oestrogen replacement became part of mainstream medicine, the great saviour. Then disaster struck.

Twenty years on doctors found that cases of endometrial cancer had risen greatly (to between four and eight times higher than those in non-hormone users) among the early generation of oestrogen takers. Progestogens were then added to help balance out the side effects of the oestrogen so that ‘oestrogen replacement therapy’ became ‘hormone replacement therapy’ and most women were required to take both the hormones. Everyone became a little more cautious about hailing oestrogen as the best thing since sliced bread.

All this happened decades ago. But we are now today seeing a similar pattern developing over another hormone, progesterone – or natural progesterone as its growing number of fans prefer to describe it. Enter the new hyped-up wonder hormone, now hailed as the real and ‘natural’ hormone replacement. Is history merely repeating itself? Are we now going through another phase where everyone is jumping on the bandwagon by promoting progesterone as safe and effective before the true picture has been established?

According to its supporters progesterone can help bone density and ‘cure’ an amazing selection of menopausal symptoms. Here is a list of some of them:

• anxiety • black circles under the eyes • blurred vision • breast pain and problems • cold hands and feet • constipation • cyclic acne • depression • disturbances in appetite • dry skin • exhaustion • fibroids • infertility • insomnia • irritability • lack of sex drive • lethargy • low blood sugar • migraines • mood swings • muscle and joint pains • panic attacks • poor concentration • poor digestion • sciatica • spontaneous abortion • spontaneous bruising • stiffness • thinning hair • water retention.

Similar claims, of course, were made when oestrogen was first introduced. It was only twenty years later that questions arose about the possible side effects. The whole history of health and medicine demonstrates the wisdom of skepticism about any ‘wonder’ substance that hits the headlines. I am suspicious about anything that is claimed to cure such a wide range of symptoms. And what is so ‘natural’ about the idea of women taking progesterone? Production of both oestrogen and progesterone decline at the menopause. And while we go on making some oestrogen all our lives the production of progesterone will stop completely. So are we seriously suggesting that nature has got this all wrong? At a time in our lives when both hormones are dropping and progesterone can be absent, why then should we be adding it back in? Progesterone is needed to maintain a pregnancy, so we can understand why the body doesn’t need it at the menopause. Why replace it?

What, actually, could be more unnatural than doctoring ourselves with progesterone, when Mother Nature has arranged for its removal from the body in the normal course of events? The thinking behind the growing popularity of progesterone therapy is as follows. As inhabitants of an industrialised world we are being constantly bombarded by xenoestrogens – substances which have an oestrogenic effect on the body. These xenoestrogens are nearly all petrochemically based and can come from packaging, plastics, foods and pesticides. They have been found in formula baby milk, presumed to have originated from the packaging used to contain the milk. They are believed to have a devastating effect on fertility, reproduction and health for both humans and wildlife. A number of disturbing developments are increasingly blamed on these chemicals. In the West it is reckoned that men’s sperm count may have dropped by 50 per cent in the last ten years. Other studies have linked these chemicals to the increase in breast and testicular cancers and to endometriosis, a painful uterine disorder. This major environmental factor lies behind the theory of oestrogen dominance.

The suggestion is that many of us are suffering from oestrogen dominance because of the increased amount of xenoestrogens we encounter daily. So, the argument goes, the answer is to balance all this unwanted oestrogen with progesterone – natural progesterone. I believe that our lifestyles and our environment have a profound effect on our hormones. That is why we must take a lot of care over our nutrition, which has such an impact on the body’s biochemical processes. I don’t however believe that the answer is to introduce ever more hormones into our bodies. And the question we should ask is, just how ‘natural’ is progesterone anyway?

Progesterone has a long history. It was originally obtained from sows’ ovaries and in the late 1930s it could be synthesised from placentas in large amounts. So placentas were quick-frozen after delivery for later extraction of progesterone. After a number of years a way was found of converting diosgenin from the wild yam (Dioscorea villosa) into progesterone. This diosgenin became the starting point in the chemical manufacturing process of progesterone which was converted to the synthetic progestogen first used in birth control pills and later in Hormone Replacement Therapy. Because progesterone is a fat-soluble compound it was usually ineffective when taken by mouth because it was metabolised by the liver and never got into the bloodstream in sufficient amounts. This led to progesterone being given intra-muscularly by injection and also as a suppository inserted into the vagina or back passage. It has been used for many years in this way as a treatment for pre-menstrual syndrome. It is now available in the form of cream to rub on the surface of the skin and is sold in the USA over the counter as a cosmetic. In the UK it is sold on prescription only, which upsets many of its advocates. They claim that because the progesterone is ‘natural’ it is safe to use and should be available over the counter here too.

This ‘natural’ progesterone is often thought of as an extract from wild yam. In fact, progesterone itself is not found in wild yams. It is synthesised from the plant by a number of chemical steps which means that it is not ‘natural’ at all. The assumption was that if we ate wild yam our bodies could convert it into the biologically active human hormone progesterone. This is simply not true. While progesterone can be synthesised from diosgenin, it can only be done by a chemist in a laboratory. Our bodies are just not capable of synthesising progesterone from a substance such as wild yam. We do not have the necessary enzymatic pathways to produce this conversion. And the fact is that these progesterone creams do not contain any wild yam at all, a fact confirmed by Dr John Lee, the Californian physician who introduced ‘natural’ progesterone to the UK and has written most widely about it. As the demand for progesterone grew, the wild yam became overharvested and other sources had to be found. Now the main manufacturers use soya beans instead. The creams are fortified with the addition of USP-grade progesterone, a white powder that used to be derived from wild yam and is now more often derived from soya beans. Progesterone is called ‘natural progesterone’ to identify it as being chemically identical to the progesterone produced by humans and to differentiate it from the synthetic progestogen used in HRT.

Why, anyway, should a progesterone supplement or replacement be necessary? Cholesterol is the starting block (the precursor) of progesterone and all the other sex hormones in our bodies. As most of us know the worry has usually been that we have too much cholesterol in our diet. So the difficulty is not that we have some undesirable shortage of this progesterone starting block but that our hormonal pathways necessary for this conversion start to shut down.

You need to be aware that progesterone creams contain a powerful pharmaceutical hormone that is made in a laboratory. Because the US FDA (Food and Drug Administration) won’t allow the manufacturers of the creams to make medical claims, they are sold as cosmetics, not as hormone replacements. It is because these creams contain a pharmaceutical agent that the UK’s Medicines Control Agency will only let them be sold under prescription, and rightly so. My main concern is that women are being duped into thinking they are buying a natural herbal remedy containing wild yam. They are not: they are buying hormone replacement – just a different hormone (progesterone instead of the usual HRT combination of a form of oestrogen plus progestogen). And they may not be buying anything truly to do with wild yam, which has a very respectable reputation as a herbal treatment for menstrual and menopausal problems. Although for centuries, herbalists have indeed used wild yam in a tincture form, the effect of the herb in its pure state is very different from that of the synthesised progesterone. This wild yam is taken orally and has traditionally been used as an anti-spasmodic and anti-inflammatory herb. As is the case with so many effective herbs it is not known precisely how it acts on the body. Since the essence of herbal medicine is that all the ingredients help towards the overall therapeutic effect, diosgenin alone cannot be responsible for the wild yam’s beneficial qualities. Herbs work because they contain a host of substances – active substances, balancing substances and substances that cope with any side effects of the active substances. They are holistic and truly ‘natural’. But the ‘natural’ progesterone that is being hyped is no more ‘natural’ than a number of the plant-based oestrogen preparations that form the basis of some HRT products.

These oestrogens are ‘natural’ in the same sense that plant-based progesterone is classed as ‘natural’. The oestrogens too are synthesised in laboratory from soya beans and yams. They still have side effects, however. We need to be clear that these hormones, oestrogen and progesterone, which are synthesised in a laboratory from plants, are not natural to us. They may be chemically identical to what our bodies produce but they are powerful drugs, hence the need to put them on prescription. Plant-based progesterone is termed ‘natural’ because it has the same molecular structure as the progesterone molecule found in humans. This idea of different substances being chemically identical can be very misleading. For example, coal, diamond and graphite (the ‘lead’ in your pencil) are all chemically identical and yet they have very different properties and functions. They have the same molecular structure, but you wouldn’t expect to produce much heat by putting diamonds on fire.

You may have heard that progesterone can help menopausal symptoms and protect you from osteoporosis. The same question that is asked about HRT would have to be asked in progesterone’s case as well: when do you stop taking it? According to Dr John Lee, the answer is, “Do it until you are ninety-six and then we will reconsider.”[1] You will not be he same at seventy as you are at fifty-six, so how do you know how much to use? Are you oestrogen dominant or are your hormones doing what they are supposed to at that age anyway? Yes, you can have your hormones tested and know what the profile is, but if you then continued to use progesterone cream for years, you would need to keep having tests to know whether you are overdosing or not. It’s all a bit hit and miss.

The cream is rubbed into the skin so it can be absorbed directly into the bloodstream. A team of researchers in Belgium found that the cream tended to accumulate in the skin instead of being fully absorbed into the bloodstream.[2] Dr Lee advises applying the cream on a rotational basis to different parts of the body. You can imagine that if you use the cream for forty years, from the menopause to age ninety-six as he suggests, you will have used all the possible sites available and it is unknown what the side effects of the hormone accumulation in the fat cells will be. Dr Lee also believes that during the initial stages of using the cream it temporarily sensitises the body to oestrogen. It is oestrogen sensitivity that has been linked to breast and endometrial cancers, fibroids and endometriosis. So by using progesterone cream are you increasing the risks of disease? And progesterone has some well known side effects. In the British National Formulary (BNF), which many doctors have in their surgeries, progesterone is listed separately from progestogens. And according to the BNF the side effects of progesterone include acne, urticaria, fluid retention, weight changes, gastrointestinal disturbances, changes in libido, breast discomfort and menstrual irregularities. Claims have been put forward that progesterone can protect against breast cancer, although there are arguments that higher levels of progesterone may be a risk factor for breast cancer.[3] In animal studies cancer of the ovary, uterus and breast were all linked to increased progesterone.[4]

Even Dr Lee admits that women taking ‘natural’ progesterone may experience exaggerated pre-menstrual or menopausal symptoms at the beginning. There are possibilities of breakthrough bleeding (bleeding that occurs at times in the cycle other than during a period) and other cycle irregularities as well. Linda, who is forty-seven, came to see me after using a progesterone cream over a period of two months. She had been recommended to use it even though she had had no menopausal symptoms and was still getting regular periods. She then started to get breakthrough bleeding halfway through the month. She was obviously concerned about this but was told that it was ‘normal’ and her body would adjust. The bleeding continued, so she decided to stop using her cream. At this point, she was overwhelmed by hot flushes and tiredness which she had not had before. Linda was getting hot all over, and waking up during the night; then she would feel really cold. She had lost her sex drive and felt ‘very fed up’. By this time she had not had a period for six weeks which was very unusual for her. Obviously she was worried. I recommended a good nutritional programme tailored to her needs and herbs to redress the imbalance. By the time she returned in a month, the hot flushes had gone, her energy was back and her periods had returned. I felt that the progesterone had had a pronounced effect on her hormone levels and it was only by taking a more gentle, natural approach that her body was able to balance itself.

It is true that Dr Lee’s research appears to demonstrate that progesterone cream has improved bone density among his patients who could not take oestrogen therapy. But his admirable desire to help those women who could not take HRT leaves a fundamental question mark over the results of his surveys since it means there is no ‘control’ group not taking progesterone whose results could be compared. The Natural Osteoporosis Society (NOS) marks its concern by stating that there has been ‘little validated scientific research into the effects of progesterone alone on bone density or fracture risk.’ NOS medical advisers do not recommend the use of ‘natural progesterone’ creams to prevent osteoporosis (or to counteract the effect of oestrogen in HRT products). Their recommendations for healthy bones include a well-balanced diet, regular exercise, no smoking and a minimal intake of alcohol. Dr Lee also made recommendations on exercise, diet and nutrient supplements as part of the treatment. It could well be that these factors, rather than the progesterone itself, were responsible for the improvement in his patients.

This is very important. My main fear is that the media hype about progesterone and the desire for easy solutions to a myriad of complaints are obscuring the real issues. Are we really falling into the same trap that we did in the Fifties and Sixties when oestrogen was hailed as the wonder cure for menopausal women? First we try one hormone, then another. First it was oestrogen. Now it’s progesterone. Both, I believe, are short-sighted short-term solutions which may have long-term negative effects. Surely the aim is to get our bodies back in balance naturally – and to allow our bodies to do this themselves. By adding in any kind of direct hormone we are never addressing the fundamental cause of problems. If you stop the cream, you are back to square one: your body will not have become any healthier in the process.

There is the possibility too that supplying something from an outside source merely encourages the body to produce less of its own. This is known to happen when people are given the thyroid hormone thyroxin. Our bodies are extremely clever. Why produce something yourself when it is being supplied from the outside and somebody else can do the work! And can it be sensible for women to take progesterone supplements after the menopause when the body’s own production of the hormone stops quite naturally? Its fans talk of progesterone as the ‘missing’ hormone. But after a certain stage of our lives it’s not supposed to be there anyway.

‘Natural’ progesterone is being touted as a ‘natural’ alternative to HRT. But there is nothing natural or alternative about it. The theory behind it is the same as the theory behind HRT – that menopausal women are suffering from a hormone deficiency disorder, a modern complaint that has arisen because we are now living way beyond our reproductive years. That is how the medical establishment, when pressed, explains and justifies the case for hormone supplementation.

The whole approach of this book is to get you healthy naturally so that your body has the capability to balance your hormones naturally. You change your nutrition, you add in food supplements (substances you would normally eat but which perhaps you need in more concentrated forms for a while), your digestion and absorption are improved. Herbal medicine, acupuncture and homoeopathy can be used where appropriate. The result is a state of good health and balance. Isn’t this really the best way forward?

It was almost twenty years before it was realised that oestrogen replacement therapy had increased the risk of endometrial cancer dramatically. Are we going to have to wait another twenty years for the progesterone time-bomb to explode after we have all been used as human guinea pigs?

[Editor’s Note: Readers should be aware that much of the research regarding ‘progesterone’ has been criticised as being inaccurate and/or misleading. For a full discussion and critique of research, the reader is referred to How Safe is Naural Progesterone by Celia Wright, Factsheet No. 5 from the Natural Progesterone Service, address details on page 46.]


1.    J. Lee, What Your Doctor May Not Tell You About the Menopause, Warner Books (1996)
2.    Mauvis-Jarvis et al., Pecutaneous Absorption of Steroids (1980)
3.    D. Grimes, Fertility and Sterility, (1992), 57, 3, 492-3
4.    International Agency for Research on Cancer (IARC), ‘Monographs on the Evaluation of the Carcinogenic risk of Chemicals to Humans’, December 1979.

Extracted from Natural Alternatives to HRT by Dr Marilyn Glenville. Published by Kyle Cathie Ltd (£9.99). To order your copy of the book (p&p free) or for information on appointments, consultations by post or workshops please call 0990 329244.


  1. Mrs. Gibb said..

    One thing the Editor didn't comment on is the fact that Progesterone is also a Pre-cursor to other hormones, and that in the case of Adrenal dysfunction, Progesterone cream is helpful to women to help replace a safe level of hormones that otherwise could not be made. As the Ovaries quit their day job, the adrenal glands are supposed to take over, but in many cases, myself included, they are overwrought after years of working, looking after kids and husbands and leading high stress lives. then at Menopause we are left with not enough hormones to function, and we can develop severe symptoms such as Chronic Fatigue, Fibromyalgia and Arthritis, and low thyroid. Progesterone cream has helped me go from total disability to functioning again. without it I am freezing cold with very low (95-96) temperature, hair falling out, paralyzing weakness, palpitations and severe joint pains and stiffness. Progesterone has brought me back to Life!

  2. St said..

    They fail to mention those of us younger folk (I.e. 30s) who have low levels and trying to concieve....

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About Marilyn Glenville, PhD

Dr Marilyn Glenville PhD is a leading UK nutritionist specializing in women’s health.  She is the Former President of the Food and Health Forum at the Royal Society of Medicine and the author of a number of internationally best selling books including The Natural Health Bible for Women, Getting Pregnant Faster and Natural Solutions to the Menopause. For more information go to


Dr. Glenville runs a number of women’s health clinics in London, Tunbridge Wells and Dublin. If you are interested in a consultation, you can contact Dr. Glenville’s clinic on Tel: 0870 5329244;

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