Chinese Yam (Shan Yao), scientifically known as Dioscorea opposita, is a twining herbaceous vine from the Dioscoreaceae family.

I. Effects and Functions

1. Invigorating the Spleen and Stomach, Aiding Digestion:
   Chinese Yam contains amylase, polyphenol oxidase, and other substances that support the spleen and stomach’s digestive and absorptive functions. It is a mild tonic for the spleen and stomach, suitable as both a medicinal herb and food. It can be consumed regardless of spleen yang deficiency or stomach yin deficiency. Clinically, it is commonly used to treat spleen and stomach weakness, poor appetite with fatigue, diarrhea, and similar conditions.
2. Nourishing the Kidneys and Benefiting Essence:
   Rich in various nutrients, Chinese Yam strengthens the body and nourishes the kidneys to benefit essence. It is suitable for conditions such as seminal emission due to kidney deficiency, excessive vaginal discharge in women, and frequent urination.
3. Benefiting the Lungs and Stopping Cough:
   Chinese Yam contains saponins and mucilage, which provide lubricating and moistening effects. This makes it effective for benefiting lung qi, nourishing lung yin, and treating chronic cough with phlegm due to lung deficiency.
4. Lowering Blood Sugar:
   The mucoprotein in Chinese Yam has blood sugar-lowering properties, making it a valuable dietary therapy option for managing diabetes and an ideal food for diabetic patients.

II. Contraindications

1. Use Sparingly in Constipation:
   Chinese Yam is rich in starch, so individuals experiencing chest and abdominal distension, dry stools, or constipation should consume it sparingly. It can be resumed once these symptoms subside.
2. Diabetic Patients Should Avoid Excessive Consumption:
   While the mucoprotein in Chinese Yam helps lower blood sugar, it is a starchy root vegetable. Excessive intake may not reduce blood sugar but could instead cause it to rise. Therefore, people with diabetes should avoid consuming large amounts at once. If some patients prefer Chinese Yam, they should reduce their intake of staple foods accordingly to avoid counterproductive effects.
3. Avoid Taking with Alkaline Drugs:
   Chinese Yam contains amylase, which can be rendered ineffective when taken with alkaline drugs. This reduces the herb’s nutritional value, so co-administration with such medications should be avoided.

When using Chinese Yam, it is recommended to follow TCM principles and consult a practitioner, especially for those with specific conditions, to ensure safe and effective use.