Chinese yam
Dioscorea polystachya · 山药
Vegetables. Chinese Medicine.
Also called Shan yao, Huai shan yao, Nagaimo
Pinyin: Shān Yào
A starchy root eaten as a vegetable. Chinese medicine uses it to support digestion, the lungs and the kidneys.
Did you know? Its Chinese name, shan yao, means roughly mountain medicine, a nod to its use as both food and medicine.
What it may help, and how strong the proof is
- Blood sugar. Some lab and animal studies show lower blood sugar. Human trials are few and small.Traditional proof
- Digestion & gut health. Traditional use for weak digestion and loose stools. Trials mostly test formulas that include yam.Traditional proof
- Kidneys, bladder & UTIs. Traditional use for kidney weakness and frequent urination. No good human trials.Traditional proof
Parts of the body
Pancreas & blood sugar, Gut & intestines, Stomach, Kidneys & bladder
Traditional use
Traditional Chinese Medicine uses shan yao to strengthen the Spleen and Lung and to support Kidney essence (deep reserves). It is a key herb in Liu Wei Di Huang Wan (Six Flavor Rehmannia Pill) and Shen Ling Bai Zhu San.
How it is classified
How people take it
Usually cooked as food. Traditional decoctions use it in moderate amounts. No human dose studies exist for the herb alone.
Food, decoction, powder and tea.
Where to get it
Grown in China, Japan and Korea. Sold as fresh root (a food), dried slices, powder and capsules. Fresh yam is often sold as nagaimo in Asian grocery stores.
Be careful
Food-level safety. Raw yam can irritate the skin and throat, so cook it first. Yams contain oxalates, so people with a history of kidney stones should check with a clinician.
Avoid if: kidney stones.
Mixing with other things
- Works well together
Bai zhu and shan yao are both in Shen Ling Bai Zhu San (Ginseng, Poria and Atractylodes Powder), used for weak digestion.
- Works well together
Poria and shan yao are both in Shen Ling Bai Zhu San (Ginseng, Poria and Atractylodes Powder) for weak digestion.
- Works well together
Shan yao and shu di huang are the two main herbs in Liu Wei Di Huang Wan (Six Flavor Rehmannia Pill), a classic kidney formula.
- Works well together
Shan yao and shan zhu yu are both in Liu Wei Di Huang Wan, used in tradition for Kidney Yin.
- Works well together
Paired with Chinese yam in Shen Ling Bai Zhu San to support digestion.
- Works well together
Paired with Chinese yam in Shen Ling Bai Zhu San to strengthen digestion.
- Worth knowingDiabetes medicine (metformin, insulin, glipizide, Ozempic)
Lab and small studies suggest yam may lower blood sugar. Check blood sugar if you take diabetes medicine.
Found in these formulas
Six Flavor Rehmannia (TCM)
The honest take
Chinese yam is a common food with good nutrition and little risk. Its medicinal claims for digestion, kidney health and blood sugar come mostly from tradition or lab work. Human research on yam alone is thin.