Progesterone is a hormone from a corpus luteum, formed by the cyclical
rupture of an ovarian follicle. Progesterone is necessary for proper uterine and
breast development and function.
Where is it found?
Progesterone is produced in the female body in the ovaries. Progesterone production is high during the luteal phase (second portion) of the menstrual cycle and low during the follicular phase (first portion), as well as being low before puberty and after menopause.
Supplemental sources of progesterone are available in oral and cream forms, as well as lozenges, suppositories, and injectable forms. “Natural” progesterone refers to the molecule that is identical in chemical structure to the progesterone produced in the body, even if the molecule is synthesised in a laboratory.
Progestins are found in oral contraceptive pills and are used in conventional hormone replacement therapy.
Wild yam contains precursors to progesterone (such as diosgenin) that can be converted through a chemical process in the laboratory into progesterone—the exact same molecule made in the human body. However, contrary to popular claims, the diosgenin in wild yams cannot be converted into progesterone in the body.1 2 Women who require progesterone should consult their physician and not rely on wild yam or other herbs.
Pregnenolone, another hormone produced by the body, is converted by the body into progesterone. However, it is not clear what effect supplementing with pregnenolone will have on progesterone production in the body.
Progesterone has been used in connection with the following conditions (refer to the individual health concern for complete information):
Who is likely to be deficient?
Postmenopausal women have reduced production of progesterone. While this “deficiency” is normal, progesterone, including the natural forms of progesterone, has been found to relieve menopausal symptoms when used in combination with oestrogen replacement therapy.3
How much is usually taken?
The proper amount of progesterone for a woman should be determined in consultation with a doctor. Some research with the natural, oral form of progesterone has used 200 mg per day.4 Progesterone is used in much lower amounts—such as 20–70 mg per day—by most doctors who prescribe topical natural progesterone. However, the ability of skin-applied progesterone to achieve effective levels in the body is the source of considerable debate.5 Although progesterone is a natural substance, oral progesterone supplements are available by prescription only. High-dose topical progesterone cream is also treated like a drug and requires a prescription. A few creams containing lower amounts of progesterone are sold without prescription.
Are there any side effects or interactions?
Progesterone is a hormone and, as such, concerns about its inappropriate use have been raised. A physician should be consulted before using this hormone as a supplement. Few side effects have been associated with topical progesterone creams but can include skin reactions. Effects of natural progesterone on breast cancer risk remain unclear. Research has suggested both increased and reduced risk.
Synthetic progestins have many well-known side effects, including the increase of LDL (“bad”) cholesterol and the decrease of HDL (“good”) cholesterol. Other side effects reported with synthetic progestins include bloating, breast soreness, depression, and mood swings. Natural progesterone has been shown to have no adverse effect on HDL cholesterol levels.6 Overall, natural progesterone is considerably safer than progestins and is therefore preferred by many doctors in situations where either would be effective.7
At the time of writing, there were no well-known drug interactions with progesterone.
References
1. Araghiniknam M, Chung S, Nelson-White T, et al. Antioxidant activity of dioscorea and dehydroepiandrosterone (DHEA) in older humans. Life Sci 1996;11:147–57.
2. Dollbaum CM. Lab analyses of salivary DHEA and progesterone following ingestion of yam-containing products. Townsend Letter for Doctors and Patients: Oct 1995, 104.
3. Hargrove JT, Maxson WS, Wentz AC, et al. Menopausal hormone replacement therapy with continuous daily oral micronized estradiol and progesterone. Obstet Gynecol 1989;73:606–12.
4. Hargrove JT, Osteen KG. An alternative method of hormone replacement therapy using the natural sex steroids. Infert Repro Med Clin N Am 1995;6:653–74.
5. Cooper A, Spencer C, Whitehead MI, et al. Systemic absorption of progesterone from Progest cream in postmenopausal women. Lancet 1998;351:1255–56 [letter] and Lancet 1998;352:905–6 [comments].
6. Ottosson UB, Johansson BG, von Schoultz B. Subfractions of high-density lipoprotein cholesterol during estrogen replacement therapy: a comparison between progestogens and natural progesterone. Am J Obstet Gynecol. 1985;151:746–50.
7. Hargrove JT, Osteen KG. An alternative method of hormone replacement therapy using the natural sex steroids. Infert Repro Med Clin N Am 1995;6:653–74.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.
2007-09-01