What is Chinese yam?

Chinese yam (Dioscorea polystachya or Dioscorea batatas) is an ornamental vine that is native to Asia. It also grows in North America, but it isn’t related to the sweet potatoes called yams that are popular there. Other names for Chinese yam are cinnamon vine, and shan yao.

Chinese yam is used in Chinese herbal medicine, traditionally to treat disorders related to the stomach, spleen, lungs, and kidneys.

The roots of Chinese yam contain diosgenin, which can be used to produce steroids such as estrogen and progesterone in a lab.

While the tuber and bulbs of Chinese yam are edible, generally only the tuber is consumed as food.

As an herbal treatment, Chinese yam is mainly used to target the stomach and spleen, but also thought to help the lungs and kidneys. It can help treat:

  • poor appetite
  • chronic diarrhea
  • asthma
  • dry coughs
  • frequent urination
  • diabetes

Chinese yam contains allantoin, a natural compound that can accelerate the growth of healthy tissue and reduce healing time. Topically, Chinese yam can be applied to ulcers, boils, and abscesses on the skin for treatment. Its leaf juices can also treat scorpion stings and snakebites.

The diosgenin in its roots is a phytoestrogen, a natural, plant-based estrogen. When processed in a lab, diosgenin can be used to manufacture progesterone, although in its original form, Chinese yam doesn’t contain progesterone or other human hormones.

Chinese yam and other wild yam extracts are often promoted to women as a natural alternative to postmenopausal hormone therapy. However, there is no scientific evidence to support claims regarding its safety or effectiveness.

People with conditions related to the stomach, spleen, kidneys, lungs, or skin may benefit from Chinese yam. In addition to these uses, promoters of the herb claim it can be used as a remedy for many conditions, including:

  • hot flashes associated with menopause
  • postmenopausal vaginal dryness
  • premenstrual syndrome (PMS)
  • gallbladder problems
  • rheumatoid arthritis
  • menstrual disorders
  • osteoporosis
  • fatigue
  • digestion disorders
  • dry or chronic cough
  • asthma

This study on the gastrointestinal function in rats shows that Chinese yam extract not only aids in digestion but can help turn some intestinal flora in the stomach into helpful bacteria.

This study shows that Chinese yam also has antioxidant properties. The study concludes that Chinese yam contains trace amounts of zinc, manganese, iron, copper, and selenium, and that taking it as a daily supplement is beneficial as an antioxidant.

Chinese yam can also help with diabetes, by modulating oxidative stress, antioxidant activities, and lipid profiles, as this study shows. It can also improve kidney and liver function.

Chinese yam extract also has the potential to help prevent atherosclerosis, a disease in which plaque builds up in the arteries, according to this study.

In addition to its potential medicinal properties, Chinese yam is a nutritious food. It primarily consists of water and starch and is a source of:

  • vitamin B-1
  • vitamin C
  • mucilage
  • amylase
  • amino acids
  • glutamine

Chinese yam is safe for most adults, but if you’re taking medication, talk to your doctor about possible side effects.

Though Chinese yam doesn’t contain estrogen, it has properties that can cause it to act like a mild form of estrogen. It can negatively interact with hormone replacement therapy or birth control pills, and pregnant or breast-feeding women should avoid it, as should women with hormone-sensitive disorders, such as:

  • endometriosis
  • uterine fibrosis
  • cancers of the breast, uterus, or ovaries

Allergic reactions are rare, but can include rashes and asthma. Large doses of Chinese yam can cause:

  • nausea
  • vomiting
  • diarrhea

People with a protein S-deficiency should also avoid Chinese yam because its estrogen-like properties may increase the risk of blood clots.

In its natural form, Chinese yam can be eaten:

  • raw
  • baked
  • boiled
  • fried
  • mashed
  • in soup

Chinese yam is also available as:

  • liquid
  • capsules
  • dried root
  • extract, or tea

Chinese yam is also administered in creams and gels that can be applied directly to your skin. Some of these may contain synthetic progesterone, though they may be promoted as containing natural progesterone. Other additions to these compounds can include vitamins, minerals, and other herbs.

Chinese yam is a versatile tuber, with many beneficial health qualities, from helping with diarrhea, to relieving diabetes symptoms, to general antioxidant benefits. It can also be prepared and taken in many ways and eaten simply for its nutritional value. Be sure to talk to your doctor before adding it to your diet and about potential side effects.