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.
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.
Contraindications*: This herb should be used with caution when there is Excess Heat or Dampness, especially Dampness in the abdomen.
Source date: 1826 AD
Number of ingredients: 10 herbs
Formula key actions: Tonifies the Middle Burner. Removes Dampness. Stops vaginal discharge. Strengthens the Spleen.
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.
Source date: 1826 AD
Number of ingredients: 5 herbs
Formula key actions: Strengthens the Spleen. Dries Dampness. Clears Heat. Stops vaginal discharge.
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.
Source date: 1119 AD
Number of ingredients: 6 herbs
Formula key actions: Nutritive tonic for the Liver and Kidney Yin Essence (nourishes the parasympathetic nervous system).
Shan Yao is a deputy ingredient in Liu Wei Di Huang Wan. This means it helps the king ingredient(s) treat the main pattern or it serves to treat a coexisting pattern.
In Liu Wei Di Huang Wan, Shan Yao stabilizes the Essence by tonifying the Spleen. Indeed, to reinforce Essence and improve its function, the Spleen (the source of postnatal Essence) must function properly.
In Traditional Chinese Medicine (TCM), yam are plants that belong 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 yam are plants that are Neutral in nature. This means that yam typically don'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 yam means that you don't have to worry about that!
Yam also taste 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 yam tend 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 yam are 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.
A mixture consisting of Rhizoma Dioscoreae has a good nutritional and health promoting effect on pregnancy.1
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.
Yam are also eaten as food. It is used as an ingredient in dishes such as Stir-fried Chinese Yam or Sautéed Yam with Soy Sauce.