Da Huang commonly known as Radix et Rhizoma Rhei is the root and rhizome of Rheum palmatum, Rheum tanguticum, or Rheum officinale, which is a perennial herb belonging to the family Polygonaceae. It is a relatively practical and common Chinese herbal medicine, which first appeared in <Shennong Ben Cao Jing> in the late Western Han Dynasty (about 100 BC).
There are about 60 species of Rheum, which are mainly distributed in the temperate and subtropical alpine mountains of Asia. Some of these species have been introduced into Europe and North America. The genus also includes edible rhubarb.
Rheum palmatum is commonly called Chinese rhubarb, Ornamental rhubarb, Turkey rhubarb, or East Indian rhubarb. This plant is cold-tolerant and not resistant to high temperatures and likes a cool and humid climate. It often grows on mountain slopes or valley wetlands at an altitude of 1,500-4,400 meters. It can be found in Gansu, Sichuan, Qinghai, Northwest Yunnan, and eastern Tibet.
Rheum tanguticum is an endangered medicinal plant endemic to China. It grows in high mountains and valleys at an altitude of 1,600-3,000 meters. It can be found in Gansu, Qinghai, and the border between Qinghai and Tibet.
Rheum officinale literally means medicinal rhubarb. It is endemic to China, where it occurs in the provinces of Guizhou, southwestern Henan, western Hubei, Shaanxi, Sichuan, and Yunnan. Its petioles can be eaten raw or cooked.
In the early spring and late autumn each year, people gather the roots and rhizomes of Rheum palmatum, Rheum tanguticum, or Rheum officinale, remove their fibrous roots and outer skin, cut them into segments, dry them, steam or stir-fry them with wine, or carbonize them, and make them into Chinese herbs.
Da Huang contains emodin, rhein, chrysophanol, aloe-emodin, 1,3,8-trihydroxyanthraquinone, emodin methyl ether, chrysaron, isoemodin, rheinoside, rhein glucoside, physcionmonoglucoside, aloe-emodin monoglucoside, emodin glucoside, chrysophanol glucoside, dianthrones, sennoside, palmitic acid, linoleic acid, dodecanoic acid, stilbene, tannins, flavonoids, polysaccharides, butyrophenones, naphthalene derivatives, volatile oils, sterols, and some trace elements.
Generally, light yellow Da Huang with obvious silky stripes and oil spots on the cross-section is the best.
According to <Compendium of Materia Medica>, the medicinal property of Da Huang is relatively cold, with a bitter taste. It has a certain therapeutic effect on the pathological changes of the spleen, stomach, large intestine, liver, and pericardium meridians.
In traditional Chinese medicine, Da Huang is often used to relieve constipation and eliminate accumulation, clear heat and purge fire, cool blood and remove toxin, remove blood stasis and stimulate menstrual flow, treat tenesmus, hemoptysis, epistaxis, upper gastrointestinal bleeding, aphtha, skin ulcer, acute mastitis, acute appendicitis, postpartum lochia, jaundice, biliary colic, acute pancreatitis, pediatric acute nephritis, seborrheic dermatitis, herpes zoster, hyperlipidemia, obesity, frostbites, burns, and scalds.
About 400 kinds of traditional Chinese medicine prescriptions contain Da Huang, such as Lianhua Qingwen capsule, Ma Zi Ren Wan, Niu Huang Jie Du Pian, and Huang Lian Shang Qing Wan.
Health benefits of Da Huang
- Anti-inflammation, anti-virus, anti-oxidation, and anti-tumor.
- Increasing intestinal peristalsis, inhibiting the absorption of water in the intestine, and promoting defecation.
- Inhibiting the secretion of gastric acid, reducing protease activity, and preventing gastric and duodenal ulcers.
- Enhancing myocardial contractility, increasing heart rate, and preventing cardiovascular diseases caused by atherosclerosis or carotid artery stenosis.
- Reducing the damage of CCL4 to liver tissue and protecting the liver.
- Relaxing the bile duct sphincter and relieving the pain caused by spasm of the bile duct sphincter.
- Promoting the secretion of bile and digestive enzymes to aiding digestion.
- Promoting urination, reducing the reabsorption of amino nitrogen in the intestine, and improving the metabolism of nitrogenous waste in the body.
- Delaying glomerular sclerosis and renal interstitial fibrosis, and alleviating clinical symptoms of chronic renal failure patients.
- Shortening the clotting time, reducing the permeability of capillaries, improving the fragility of blood vessels, and promoting blood coagulation.
- Reducing blood viscosity, inhibiting cholesterol absorption, reducing lipoprotein synthesis, lowering total cholesterol, and triglycerides.
- Cooling blood, treating hematemesis, hemoptysis, and epistaxis caused by blood heat.
- Purging fire, treating inflamed eyes, sore throat, swollen gums, and oral ulcers caused by the flaring up of fire.
- Removing heat toxins, relieving skin swelling and pain, and treating sores and carbuncles caused by heat toxins.
- Promoting blood circulation and removing blood stasis, and treating postpartum lochia, and abdominal pain caused by blood stasis.
- Stimulating menstrual flow, treating amenorrhea and delayed menstruation caused by blood stasis.
- Clearing damp-heat in the large intestine, treating dysentery, jaundice, difficult and painful urination caused by damp-heat.
- Eliminating phlegm, treating epilepsy, cough, asthma, thick phlegm, and constipation caused by the phlegm-fire disturbing heart.
- Inhibiting staphylococcus aureus, pseudomonas aeruginosa, Escherichia coli, diphtheria bacillus, typhoid bacillus, paratyphoid bacillus, pneumococcus, and dysentery bacillus.
- Its volatile oils can promote the production of hemolysin in sheep red blood cells (SRBC) sensitized mice, and enhance immunity.
- Emodin can inhibit the differentiation and maturation of dendritic cells (DC), induce T cells to enhance immune tolerance in organ transplantation, and attenuate immune rejection.
Da Huang is used with other Chinese herbs
- It with Mang Xiao (Natrii Sulfas), Hou Po (Magnolia Bark), and Zhi Shi (Fructus Aurantii Immaturus) can induce diarrhea and treat constipation caused by sthenic fever.
- It with Huang Lian (Rhizoma Coptidis) and Huang Qin (Radix Scutellariae) can treat hemoptysis and epistaxis caused by blood heat.
- It with Huang Qin (Radix Scutellariae) and Zhi Zi (Fructus Gardeniae) can treat inflamed eyes, sore throat, swollen gums, and oral ulcers caused by the flaring up of fire.
- It with Jin Yin Hua (Flos Lonicerae), Pu Gong Ying (Dandelion), and Lian Qiao (Fructus Forsythiae) can treat sores and carbuncles caused by heat toxins.
- It with Mu Dan Pi (Cortex Moutan), Tao Ren (Semen Persicae), and Mang Xiao (Natrii Sulfas) can alleviate abdominal pain caused by acute appendicitis.
- It with Tao Ren (Semen Persicae) and Gui Zhi (cassia twig) can treat amenorrhea caused by blood stasis.
The topical application of Da Huang, Di Yu (Radix Sanguisorbae), and sesame oil can relieve burns and scalds.
Side effects of Da Huang
Studies have confirmed that it not only contains anthraquinones that induce diarrhea but also contains tannins that cause constipation. Taking it may cause diarrhea first and then constipation.
Overdose of it may cause nausea, vomiting, abdominal pain, diarrhea, fever, epilepsy, or rash.
Taking it for a long time may cause spleen and stomach damage, muscle weakness, bone loss, potassium loss, or arrhythmia.
There is a report of kidney failure in someone who took a product containing Da Huang. But it’s not known for sure if Da Huang was the actual cause of kidney failure.
Precautions of Da Huang
- The dosage of Da Huang should be controlled at 5-15g.
- It can be made into decoctions, pills, ointments, lotions, or ground for external use.
- When making its decoction, it is recommended to boil it after boiling water.
- It is not suitable for long-term decocting.
- The unprocessed Da Huang is recommended for inducing diarrhea, the wine-fried Da Huang is for promoting blood circulation and removing blood stasis, and the carbonized Da Huang is for stopping bleeding.
- People with weakness of spleen and stomach should not take it.
- Women should not take it during menstruation, pregnancy, or lactation.
- Children should take it under the guidance of a physician.
- People with intestinal obstruction, Crohn’s disease, colitis, or irritable bowel syndrome should not take it.
- People with kidney stones or liver diseases should take it.
- Patients with habitual constipation may make constipation worse when taking it.
- It should not be used with enzymatic drugs, aminopyrine drugs, vitamins, niacin, caffeine, chloramphenicol, anisodamine, belladonna, propantheline bromide, ferrous sulfate, tetracycline, pilocarpine, neostigmine, metronidazole, ampicillin, lincomycin, cephalosporins, sulfonamides, or antacids.