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Posts tagged ‘phytoestrogen’


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What is it?

Wild yam is a plant. It contains a chemical, diosgenin, which can be made in the laboratory into various steroids, such as estrogen and dehydroepiandrosterone (DHEA). The root and the bulb of the plant are used as a source of diosgenin, which is prepared as an “extract,” a liquid that contains concentrated diosgenin.

There are over 600 species of wild yam. Some species are grown specifically as a source of diosgenin for laboratories to use in making steroids. These species are generally not eaten due to a bitter flavor. Only about 12 of the 600 species are considered edible.

Diosgenin or wild yam is often promoted as a “natural alterative” to estrogen therapy, so you will see it used for estrogen replacement therapy, vaginal dryness in older women, PMS (premenstrual syndrome), menstrual cramps, weak bones (osteoporosis), increasing energy and sexual drive in men and women, and breast enlargement. Wild yam does seem to have some estrogen-like activity, but it is not actually converted into estrogen in the body. It takes a laboratory to do that.

Similarly, you will also see wild yam and diosgenin promoted as a “natural DHEA.” This is because in the laboratory DHEA is made from diosgenin, but this chemical reaction is not believed to occur in the human body. So taking wild yam extract will not increase DHEA levels in people. Individuals who are interested in taking DHEA should avoid wild yam products labeled as “natural DHEA.”

Wild yam is also used for treating a disorder of the intestines called diverticulosis, gallbladder pain, rheumatoid arthritis, and for increasing energy.

Some women apply wild yam creams to the skin to reduce menopausal symptoms such as hot flashes.

How effective is it?

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for WILD YAM are as follows:

Possibly ineffective for…

  • Menopausal symptoms. Applying wild yam cream to the skin for 3 months does not seem to relieve menopausal symptoms such as hot flashes and night sweats. It also does not seem to affect levels of hormones such as follicle stimulating hormone (FSH), estradiol, or progesterone, which play a role in menopause.

Insufficient evidence to rate effectiveness for…

  • Use as a natural alternative to estrogens.
  • Postmenopausal vaginal dryness.
  • PMS (Premenstrual syndrome).
  • Weak bones (osteoporosis).
  • Increasing energy and sexual desire in men and women.
  • Gallbladder problems.
  • Painful menstrual periods.
  • Rheumatoid arthritis.
  • Infertility.
  • Menstrual disorders.
  • Other conditions.

More evidence is needed to rate the effectiveness of wild yam for these uses.

How does it work?

Wild yam contains a chemical that can be made into various steroids, such as estrogen, in the laboratory. However, the body can’t change wild yam to estrogen.

Are there safety concerns?

Wild yam is POSSIBLY SAFE when taken by mouth or applied to the skin. Large amounts can cause vomiting.

Special precautions & warnings:

Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking wild yam if you are pregnant or breast feeding. Stay on the safe side and avoid use.

Hormone-sensitive condition such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Wild yam might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, do not use wild yam.

Protein S deficiency: People with protein S deficiency have an increased risk of forming clots. There is some concern that wild yam might increase the risk of clot formation in these people because it might act like estrogen. There is one case report of a patient with protein S deficiency and systemic lupus erythematosus (SLE) who developed a clot in the vein serving the retina in her eye 3 days after taking a combination product containing wild yam, dong quai, red clover, and black cohosh. If you have protein S deficiency, it is best to avoid using wild yam until more is known.

Are there interactions with medications?

Be cautious with this combination.
Wild yam might have some of the same effects as estrogen. Taking wild yam along with estrogen pills might decrease the effects of estrogen pills.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

Are there interactions with herbs and supplements?

There are no known interactions with herbs and supplements.

Are there interactions with foods?

There are no known interactions with foods.

What dose is used?

The appropriate dose of wild yam depends on several factors such as the user’s age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for wild yam. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.


To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.


  1. Hudson t, Standish L, Breed C, and et al. Clinical and endocrinological effects of a menopausal botanical formula. Journal of Naturopathic Medicine 1997;7:73-77.
  2. Zagoya JCD, Laguna J, and Guzman-Garcia J. Studies on the regulation of cholesterol metabolism by the use of structural analogue, diosgenin. Biochemical Pharmacology 1971;20:3471-3480.
  3. Datta K, Datta SK, and Datta PC. Pharmacognostic evaluation of potential yams Dioscorea. Journal of Economic and Taxonomic Botany 1984;5:181-196.
  4. Araghiniknam M, Chung S, Nelson-White T, and et al. Antioxidant activity of Dioscorea and dehydroepiandrosterone (DHEA) in older humans. Life Sciences 1996;59:L147-L157.

The Soy Renaissance

In addition to its many nutritional benefits, soy may offer relief from common discomforts associated with menopause. Learn more about this super food and how it might help you.

In last week’s newsletter, I touched on the value of dietary soy, especially for women’s wellness. Although the health benefits of soy have been questioned, I believe a negative reputation has been encouraged by lobbyists for the meat and dairy industries. That said, I’m not a “soy nut,” and I do think that traditional diets with meat, dairy or fish protein can be healthy.

Much of the health value of soybeans is actually found in an interesting series of soy components called isoflavones. Isoflavones are a category of natural substances called phytoestrogens (phyto = plant). These plant compounds are believed to have hormone-like effects, but there is more to these potent and versatile natural substances. Phytoestrogens have many biological effects, and they may be best viewed as “adaptogens,” or biological-response modifiers, rather than simple estrogens.

The most abundant and common source of isoflavones are soybeans, which contain the isoflavones genistein, daidzein and glycetein. Phytoestrogens are found in red clover, lignans, fruit or grain fibers and phytosterols. Phytosterols are present in beans, cereals and grass sprouts. Active occurring phytoestrogens are transformed by bacteria in the colon or body enzyme systems into isoflavones or related compounds with estrogen-balancing effects.

Population studies of menopausal women provide convincing evidence that isoflavone-rich soy foods may reduce the occurrence or severity of hot flashes and other discomforts of menopause. Women following traditional soy-enriched diets in Japan have been found to have much higher levels of phytoestrogens in their urine than women in Western societies who follow the Standard American Diet. Along with this finding of high isoflavone intake are reports of significantly less menopausal discomforts, especially a low occurrence of hot flashes, in Japanese women.

The beneficial effects of soy have been attributed to the presence of the isoflavones genistein and daidzein; and these isoflavones have been concentrated and added to many dietary supplements for menopause and PMS management. More than 20 recent clinical trials have tested the ability of soy isoflavones, taken in concentrated forms (pills or soy protein isolates), to reduce hot flashes in menopausal women. While results have been mixed, approximately half of study participants reported improvements in hot flashes in just a few weeks. I believe variations in dosage may account for variations in results.

Soy isoflavones have varying levels of potency in terms of an estrogen-like action. However, they are all weak estrogens or modulators of estrogen’s effects on the body. I have been impressed by the benefits of using isoflavones of different origins together in dietary supplements. With these combinations, additive benefits are seen, and lower dosages of each isoflavone can be used together for greater effects (synergy). In particular, a combination of soy isoflavones and red clover isoflavones may be more effective for hot flashes.

There is a long history of precedent for the safety of soy foods. There are no studies in humans showing significant adverse effects of soy isoflavones, even when taken in relatively large doses (100 mg or more). Reviews of medical and scientific literature suggest that isoflavones in soy may exert significant protective effects in both animals and humans. (See Holt, S., “The Soy Revolution,” Dell Publishing, N.Y., N.Y., 2000). Soy isoflavones are known to function as potent antioxidants and free radical scavengers.

Many women question whether or not plant estrogens (phytoestrogens) cause cancer. Scientists have attempted to address the safety of phytoestrogens in relationship to cancer, but there are many different types of these plant compounds. Certain phytoestrogens have beneficial effects on the body, especially when body estrogen levels are high (independent of actions on estrogen receptors). However, there is no evidence that phytoestrogens used in popular dietary supplements can lead to cancer.

Soy isoflavones appear to be quite safe when used in doses with an existing precedent for safety (up to approximately 80 mg to 100 mg of total soy isoflavones in dietary supplements). While it’s unlikely that anyone would consume more than a total daily intake of 150 mg of isoflavones even if he or she ate a heavily soy-enriched diet, isoflavone supplements are available in a wide range of doses. I would like to stress that continuous use of soy supplements with high doses of soy isoflavones should be avoided.

The complex, beneficial actions of isoflavones and other components of soy make soy foods an extremely valuable dietary addition. For a more complete account of the positive impact of soy on health, please feel free to read my books (“The Soy Revolution,” Dell Publishing, N.Y., 2000; “Soya for Health,” Mary Ann Liebert Publishers, N.Y., 1997; and “Combat Syndrome X, Y and Z”,, N.J., 2002).

Be Healthy!
Stephen Holt, MD

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