English: Yam
Chinese: 山药
Use of Shan Yao (yam) in TCM
Please note that you should never self-prescribe TCM ingredients. A TCM ingredient is almost never eaten on its own but as part of a formula containing several ingredients that act together. Please consult a professional TCM practitioner, they will be best able to guide you.
Preparation: Remove impurities, wash, cut and dry.
Dosage: 3-6g.
Main actions according to TCM*: Tonifies the Spleen and Stomach. Tonifies the Lung Qi and nourishes the Lung Yin. Nourishes the Kidneys and consolidates Jing.
Primary conditions or symptoms for which Shan Yao may be prescribed by TCM doctors*: Vaginal discharge Diarrhea Spermatorrhea Urinary incontinence Uterine prolapse Whooping cough
Contraindications*: This herb should be used with caution when there is Excess Heat or Dampness, especially Dampness in the abdomen.
Common TCM formulas in which Shan Yao is used*
Wan Dai Tang
Source date: 1826 AD
Number of ingredients: 10 herbs
Formula key actions: Tonifies the Middle Burner. Removes Dampness. Stops vaginal discharge. Strengthens the Spleen.
Conditions targeted*: PreeclampsiaOtitis media and others
Shan Yao is a king ingredient in Wan Dai Tang. Like the name indicates, it means it has more power than other ingredients in the formula.
In Wan Dai Tang, Shan Yao strengthens the Spleen, tonifies Qi, removes Dampness, and builds up the Essence. It works collaboratively with Bai Zhu to support the Girdle Vessel in securing the Channels.
Yi Huang Tang
Source date: 1826 AD
Number of ingredients: 5 herbs
Formula key actions: Strengthens the Spleen. Dries Dampness. Clears Heat. Stops vaginal discharge.
Conditions targeted*: CervicitisCervical erosion and others
Shan Yao is a king ingredient in Yi Huang Tang. Like the name indicates, it means it has more power than other ingredients in the formula.
In Yi Huang Tang, Shan Yao strengthens the Spleen and stabilizes the Penetrating Vessel and the Essence. It also works together with Qian Shi (Foxnut seeds) to tonify the Directing Vessel Deficiency. The 2 herbs are also able to support Body Fluids metabolism.
Tu Si Zi Wan
Source date: 1253 AD
Number of ingredients: 11 herbs
Formula key actions: Warms the Kidneys. Prevents abnormal leakage such as urinary incontinence or seminal emissions.
Conditions targeted*: Urinary incontinenceSeminal emission and others
Shan Yao is a king ingredient in Tu Si Zi Wan. Like the name indicates, it means it has more power than other ingredients in the formula.
In Tu Si Zi Wan, Shan Yao , together with other key herbs of the formula, tonifies the Kidneys.
Key TCM concepts behind Shan Yao's properties
In Traditional Chinese Medicine (TCM), Shan Yao belongs to the 'Tonic herbs for Qi Deficiency' category. Tonic herbs are used for patterns of Deficiency, when one lacks one of the 'Four Treasures' (Qi, Blood, Yin and Yang). Qi tonics are typically sweet and they tend to enter the Spleen and Lungs because these Organs are most involved with the production of Qi.
Furthermore Shan Yao is Neutral in nature. This means that Shan Yao typically doesn't affect the balance in your body. Balance between Yin and Yang is a key health concept in TCM. Eating too many "Hot" (Yang) ingredients can lead to an imbalance whereby one has a Yang Excess. The inverse is true as well: too many "Cold" (Yin) ingredients can lead to a Yin Excess. The Neutral nature of Shan Yao means that you don't have to worry about that!
Shan Yao also tastes Sweet. The so-called 'Five Phases' theory in Chinese Medicine states that the taste of TCM ingredients is a key determinant of their action in the body. Sweet ingredients like Shan Yao tends to slow down acute reactions and detoxify the body. They also have a tonic effect because they replenish Qi and Blood.
The tastes of ingredients in TCM also determine what Organs and Meridians they target. As such Shan Yao is thought to target the Kidney, the Lung and the Spleen. According to TCM, the Kidneys do not only regulate the urinary system but also play a key role in the reproductive system and the growth and aging process of the body. In addition to performing respiration, the Lungs are thought in TCM to be a key part of the production chain for Qi and the Body Fluids that nourish the body. The Spleen assists with digestion, Blood coagulation and Fluids metabolism in the body.
Research on Shan Yao
A mixture consisting of Rhizoma Dioscoreae has a good nutritional and health promoting effect on pregnancy.1
Sources:
1. Ling CD, Zhang ZJ, Chen ZL. (1996). Studies on nutritional effects of traditional Chinese tonics with strengthened nutrients on pregnant women and rats. Zhongguo Zhong Xi Yi Jie He Za Zhi. , 16(5):270-3.
Use of Shan Yao as food
Shan Yao is also eaten as food. It is used as an ingredient in dishes such as Stir-fried Chinese Yam or Sautéed Yam with Soy Sauce.