Wild Yam : Safety and Interactions

by MedlinePlus

(Page 2 of 2)

Safety

Allergies

Rubbing the skin with Dioscorea batatas (a yam species related to Dioscorea villosa ) has been reported to cause allergic rash. Workers exposed to Dioscorea batatas in large amounts and for a prolonged time have developed asthma that is made worse by exposure to the yam. A person who is known to have an allergy to Dioscorea batatas may also be allergic to other Dioscorea types.

Side Effects and Warnings

Rubbing the skin with Dioscorea batatas , a related yam species, has been reported to cause a rash at the site of contact. Wild yam cream caused no rash in 23 healthy women in one reported study. In another study, wild yam given by mouth was reported to cause stomach upset at high doses.

Wild yam was believed in the past to have properties similar to the reproductive hormone progesterone, but this has not been supported by scientific studies. It has been suggested that some wild yam creams might be tainted with artificial progesterone. Based on theoretical hormonal properties and possible progesterone contamination, people with hormone-sensitive conditions should use wild yam products with caution. This caution applies to people who have had blood clots or strokes and to women who take hormone replacement therapy or birth control pills. In addition, women with fibroids, endometriosis, or cancer of the breast, uterus, or ovary should be aware that these are hormone-sensitive conditions that may be affected by agents with hormonal properties.

In animal studies, compounds from the Dioscorea dumentorum species lower blood sugar levels. It is not clear whether wild yam ( Dioscorea villosa ) lowers blood sugar in humans. Caution is advised in patients with diabetes or hypoglycemia and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary.

Pregnancy and Breastfeeding

Use of wild yam is not recommended during pregnancy or breastfeeding due to lack of safety information. Wild yam is believed to cause uterine contractions, and therefore use is discouraged during pregnancy. Wild yam was once thought to have effects similar to those of reproductive hormones, although this has not been proven in scientific studies. Artificial progesterone may be added to some products.

Interactions

Interactions with Drugs

In animals, wild yam lowers blood levels of indomethacin, a non-steroidal anti-inflammatory drug, and reduces irritation of the intestine caused by indomethacin. Human studies have not been reported in this area, and it is not clear if wild yam affects the blood levels of other anti-inflammatory drugs such as ibuprofen (Advil®, Motrin®).

An early study suggests that wild yam may interfere with the body's ability to control levels of the reproductive hormone progesterone. Progesterone is a key ingredient in some hormone replacement and birth control pills. There are reports that some wild yam products may be tainted with artificial progesterone. Women taking birth control pills or hormone replacement therapy should speak with a licensed healthcare provider before starting wild yam.

It is not clear whether blood sugar is lowered by Dioscorea villosa (wild yam). Dioscoretine, a compound found in the related species Dioscorea dumentorum (Bitter or African yam), has been shown to lower blood sugar levels in rabbits and rats, but this has not been shown for Dioscorea villosa . Effects on blood sugar in humans have not been reported. Nonetheless, caution is advised when using medications that may also lower blood sugar. People taking diabetes drugs by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.

Diosgenin, thought to be the active substance in wild yam, has been found in animals to reduce absorption of cholesterol from the intestine and to lower total cholesterol levels in the blood. Studies in humans show no change in the total amount of cholesterol in the blood, although the amounts of specific types of cholesterol in the blood may be changed: low-density lipoprotein (LDL, or "bad cholesterol") and triglycerides may be lowered, and high-density lipoprotein (HDL, or "good cholesterol") may be increased. It is thought that wild yam may enhance the effects of other cholesterol-lowering medications, including fibric acid derivatives such as clofibrate (Questran®), gemfibrozil (Lopid®), and fenofibrate (Tricor®). In animals, wild yam has been found to improve the effect of clofibrate in lowering cholesterol levels.

Tinctures of wild yam may contain high amounts of alcohol and may lead to vomiting if taken with disulfiram (Antabuse®) or metronidazole (Flagyl®).

Interactions with Herbs and Dietary Supplements

In an early study, a wild yam preparation was reported to block the body's natural production of progesterone. However, this finding was not supported by later research. There have been several reports that some wild yam products are tainted with synthetic progesterone. Because wild yam may contain progesterone-like chemicals, the effects of other agents believed to have hormone-like properties, in particular those with estrogen-like properties, may be altered. Possible examples include alfalfa, black cohosh, bloodroot, burdock, hops, kudzu, licorice, pomegranate, red clover, soy, thyme, white horehound, and yucca.

It is not clear whether Dioscorea villosa (wild yam) lowers blood sugar levels. Although dioscoretine, produced by the related species Dioscorea dumentorum (Bitter or African yam), has been shown to lower blood sugar in rabbits, this reaction has not been seen with Dioscorea villosa and has not been reported in humans. Nonetheless, caution is advised when using herbs or supplements that may also lower blood glucose. Blood glucose levels may require monitoring, and doses may need adjustment. Possible examples include: Aloe vera , American ginseng, bilberry, bitter melon, burdock,fenugreek, fish oil, gymnema, horse chestnut seed extract (HCSE), marshmallow, milk thistle, Panax ginseng, rosemary, Siberian ginseng, stinging nettle, and white horehound.

Diosgenin, thought to be the active substance in wild yam, has been found in animals to reduce absorption of cholesterol from the intestine and to lower total cholesterol levels in the blood. Studies in humans show no change in the total amount of cholesterol in the blood, although the amounts of specific types of cholesterol in the blood may be changed: low-density lipoprotein (LDL, or "bad cholesterol") and triglycerides may be lowered, and high-density lipoprotein (HDL, or "good cholesterol") appears to be increased. In theory, wild yam may enhance the effects of other cholesterol-lowering agents, such as fish oil, garlic, guggul, or niacin. Vitamin C has been reported to enhance the ability of diosgenin to lower cholesterol. Further study is needed in this area.

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