The Blood-Sugar-Lowering, Lipid-Lowering, Antitumor and Antimutagenic Effects of the Chinese Herb Yuzhu (Polygonatum Odoratum)
The Chinese herb Yuzhu is the rhizome of Polygonatum odoratum, a plant of the genus Polygonatum in the lily family. In ancient bencao works it is often called Weirui; because it has a certain tonic action, some bencao works also call it Weishen. Yuzhu, as its name suggests, is shaped like a jade bamboo, mostly yellowish-white and tubular with distinct joints; hence its alternative names "Biguanzzi" (tube-stem), "Zhujiehuang" (bamboo-joint yellow), and "Zhuqigen." Yuzhu is distributed in many parts of central and southern China; that produced in Zhejiang, Hunan, and Guangdong is of the finest quality.
Traditional TCM considers Yuzhu sweet and neutral in nature, entering the lung and stomach meridians, and classifies it as a yin-tonifying herb. It is held to nourish yin and moisten the lung, and nourish the stomach and generate fluids. It treats dry cough and consumptive cough, heat disease damaging yin, dry throat and thirst, wasting-thirst (xiaoke), external contraction in yin deficiency, dizziness and vertigo, and spasmodic pain of the sinews and vessels.
The Shennong Bencao Jing says it "mainly treats stroke with great heat, inability to move, sinews that have fallen and flesh knotted, and all deficiencies. Long use removes facial dark pigment, improves complexion and moisture, lightens the body and prevents aging." The Rihuazi Bencao says it "removes vexatious heat, quenches thirst, moistens the lung and heart, supplements the five consumptions and seven impairments, deficiency damage, lower back and foot pain, and epidemic heat mania." The Fengshi Jinang uses a verse to explain its effects: "It moistens the lung and stops cough and phlegm, supplements the spleen and dispels damp-heat, nourishes the liver and treats eye injury and tearing, and benefits the kidney and removes lower-back pain and coldness of the penis." These records show that the ancients regarded Yuzhu as an anti-aging, complexion-enhancing tonic that treated "stroke with great heat," "deficiency damage," and "lower-back and foot pain."
Modern pharmacological research has found that Yuzhu lowers blood sugar and blood lipids, which suggests a scientific basis for the ancient records that Yuzhu nourishes yin, moistens dryness, and treats "spasmodic pain of the sinews and vessels." People with high blood sugar often have dry throat and parched mouth, which TCM ascribes to yin deficiency to be treated by "nourishing yin and moistening dryness"; high blood lipids affect the nervous system and cause spasmodic pain of the limb sinews and vessels. Yuzhu lowers blood lipids and thus treats spasmodic pain of the sinews and vessels. Yuzhu's action on lower-back pain has been mentioned repeatedly in various bencao works; this is closely related to its lipid-lowering effect and deserves attention. Studies show that Yuzhu used together with Baizhu (Atractylodes) and Huangqi (Astragalus) can also treat poliomyelitis, strengthening limb muscle strength. Other studies show Yuzhu combined with Shengmai San treats tachycardia of the heart-yin-deficiency type.
Modern pharmacological research has also found that Yuzhu has antitumor and antimutagenic effects. Yuzhu extract inhibits the proliferation of the human T-lymphoblastic leukemia cell line CEM, promotes the expression of surface molecules HLA-1, CD2, and CD3 on CEM cells, and raises the degree of CEM differentiation. Yuzhu extract also shortens the survival of tumor-bearing mice with intraperitoneal transplanted tumors and induces apoptosis in human colon cancer CL187 cells. All this shows Yuzhu has a certain antitumor and antimutagenic action. Yuzhu also improves the dry throat and parched mouth of leukemia patients; used together with other heat-clearing and toxicity-resolving herbs, it can also lower the body temperature of leukemia patients.
Yuzhu is mostly decocted for oral use; the common dose in decoction is 6-12 g, rising to 30-60 g when treating diabetes and cancer. It may also be boiled into an ointment, soaked in wine, or put into pills or powders. The fresh herb may even be pounded and applied externally for pruritic or exudative skin diseases.
However, not every patient is suited to Yuzhu. As a yin-nourishing herb, Yuzhu inevitably has the side effect of being cloying and obstructing the diaphragm, affecting digestion and causing loose stools and diarrhea. TCM therefore holds that those with phlegm-dampness and qi stagnation, and those with spleen deficiency and loose stools, should not take Yuzhu.