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Chinese Yam (Shanyao): Its white color enters the Lung Meridian (Lung Channel), its sweet taste returns to the Spleen, and its thick fluid benefits the Kidney. It can moisten the blood vessels, secure Qi transformation, calm cough and stabilize panting, strengthen will and nourish spirit. Its nature is neutral, so it can be taken frequently and in large doses over a long period. It is suitable to use fresh yam boiled for drinking; it should not be stir-fried, because it contains much protein, and if fried, its protein becomes scorched and dry, rendering it ineffective when consumed. If made into pills or powders, it can be ground into fine powder and steamed before use (after the formula Yiwai Shuyu Yin [Single-Ingredient Dioscorea Decoction] in the "Medical Formulas" section, several verified cases of cure using Chinese Yam are attached for reference).

[Attached Case] The mother of Wan XX from Faku County suffered from phlegm-panting and cough since she was in her thirties. For thirty years, various medicines were ineffective. Moreover, as she grew older, the disease worsened. In the spring of 1921, she developed additional symptoms such as fever, dry throat, sweating on the head, and inability to eat. A physician diagnosed it as excessive phlegm with fire and prescribed Ren Shen Qing Fei Tang [Ginseng Lung-Clearing Decoction] added with Sheng Di [Rehmanniae Radix] and Dan Pi [Moutan Cortex]. This was not only ineffective but also caused intense fever like fire and added diarrhea, leading to a critical condition. Later, she suddenly saw Yiwai Shuyu Yin [Single-Ingredient Dioscorea Decoction] in *Yixue Zhongzhong Canxi Lu* [Record of Medical Practice Integrating Traditional Chinese and Western Medicine]. She then used four liang (approx. 150g) of raw Huai Shan Yao [Dioscorea opposita] and three qian (approx. 11g) of Xuan Shen [Scrophulariae Radix], decocted in a large bowl of water, and took it slowly in warm portions several times. One dose showed effect; after three doses, the illness improved by more than half. Then, she switched to taking one liang (approx. 37.5g) of fine powder of raw Huai Shan Yao [Dioscorea opposita] cooked as porridge, twice daily, occasionally using stomach-opening medicines. Within ten days, she stabilized, and the chronic disease greatly lightened. It is estimated that long-term consumption may eradicate the root cause of the chronic disease. Another case: The wife of Wan XX suffered from loose stools/diarrhea for several years without cure, which was also cured by consuming Shan Yao [Chinese Yam] porridge.

Commentary: The efficacy of Shan Yao [Chinese Yam] has been discussed in detail after Yiwai Shuyu Yin [Single-Ingredient Dioscorea Decoction]. Regarding the treatment of diarrhea, changing the decoction to porridge is necessary indeed, because Shan Yao [Chinese Yam] juice is naturally thick and sticky. If further cooked into porridge, this thickening and sticking power increases significantly, possessing great ability to retain substances in the intestines and stomach. I recall twenty years ago, while participating in the annual examination in Tianjin, I accidentally suffered from diarrhea. After swallowing food, I felt discomfort in the stomach, followed by rumbling in the intestines and immediate diarrhea. I decocted Gan Cao [Licorice Root] soup strongly and took Chi Shi Zhi [Halloysitum Rubrum] fine powder mixed with it, but it was ineffective. Then I used white Jing Mi [Oryza Sativa Var. Glutinosa] and cooked it thoroughly over low heat into porridge, eating it as much as possible. Immediately, my spleen and stomach felt comfortable, abdominal rumbling ceased, and the diarrhea healed. Thus, we know that whatever substance is made into porridge can retain content in the gastrointestinal tract. Since Shan Yao [Chinese Yam] has an inherent astringent nature, cooking it into porridge yields even faster results. Furthermore, those with loose stools/diarrhea often have difficulty with urination. Shan Yao [Chinese Yam] can nourish the Kidney Meridian (Kidney Channel); when Kidney Yin is sufficient, urination becomes smooth naturally, and there is no risk of loose stools/diarrhea.