RHUBARB ROOT (Rheum palmatum)


Latin: Rheum palmatum, Rheum officinale, R.  species
Sanskrit: Amlavetasa
Chinese: Da huang

WHAT IT DOES: Rhubarb root is sour and bitter in taste, and cooling in action.  It is a stimulant laxative that drains inflammation from the liver, large intestine and kidney.

RATING: Yellow, due to problems with long-term usage.

SAFETY ISSUES: Do not use during pregnancy or nursing.  Do not use with bowel obstruction or gout.  Do not use in cases of severe deficiency.  Do not use long term.  Use only under supervision with inflammatory bowel disease.  Long-term use can cause hypertrophy of the liver, thyroid and stomach, as well as nausea, griping, abdominal pain, vomiting and diarrhea (reported in Huang, 1999).  Short-term or occasional use is safe in appropriate dosage unless otherwise contraindicated.

STARTING DOSAGE:
• Dried powder: one to six grams per day
• 4:1 dried decoction extract: one to three grams per day

In spite of the contraindications (which are common to most laxatives), rhubarb root is still my favorite of the readily available laxatives.  Of course with simple constipation, it is always better to try basic remedies first, like increasing dietary fiber and fluid intake, or using a small amount of magnesium at bedtime.  TCM doctors use rhubarb root to treat constipation, high fever, abdominal distension, gall stones, jaundice and, surprisingly, acute dysentery, due to the herb’s anti-bacterial activity.  They stir fry rhubarb root with wine to reduce the laxative effect when it is used for diseases other than constipation.  TAM doctors use it in formulas to treat cirrhosis of the liver, alcoholism, neurasthenia and asthma.  Recent experimental discoveries offer important evidence of rhubarb’s effect on kidney failure.

The major concern with herbs containing anthraquinones–natural laxative chemicals such as emodin and sennidin–is that long-term use can lead to dependence.  Anthraquinones stimulate peristalsis approximately 6-8 hours after ingestion.  The effects on the gut are largely topical, and the substances flush out of the system without being absorbed.  It seems that rhubarb root has an advantage over other laxatives like the more powerful senna and cascara sagrada.  Its higher tannin levels tend to tighten the bowel after 14-18 hours, somewhat limiting the possibility of the flaccid condition that can result from laxative overuse.  In fact, the tannins are the reason that small doses of rhubarb (.03 to.3 grams) can actually cause constipation.

In our clinic we treat constipation with lifestyle changes and supportive formulas containing small amounts of rhubarb root mixed with other herbs that strengthen the digestion, improve liver function and lubricate the bowel.  The rhubarb dosage can be reduced with improvements in bowel and liver health, and we often gradually switch to magnesium, the dosage of which is gradually lowered until the patient is able to get off all bowel support.

Research Highlights

• In a three-month clinical trial, alcohol extracts of rhubarb made into tablets reduced obesity complicated with hypertension, menstrual irregularities and elevated blood lipids (Chen, 1995).

• Test tube studies of emodin, an active component of rhubarb root, demonstrated inhibition of Trichomonas vaginalis (Wang, 1993).

• Oral administration of emodin cured intra-vaginal infections in mice (Wang, 1993).

• A ten-year controlled clinical double blind trial at the Xiang Shan TCM Hospital in Shanghai tracked all patients using three types of alcohol-extracted rhubarb tablets to treat chronic upper digestive bleeding.  All three types were shown to stop bleeding within 56 hours at an effectiveness rate greater than 90% (Zhou and Jiao, 1990).

• Researcher Deng Wenlong, of the Sichuan Provincial Institute of Chinese Materia Medica, presented a paper at Chengdu University of TCM in China explaining rhubarb’s traditional reputation for treating fevers and inflammatory diseases.  He began by describing endotoxins, chemicals that are released into the host as a result of the breakdown of the cell walls of Gram-negative bacteria.  He demonstrated that endotoxin content in the blood increased greatly in the presence of severe stress, inflammation or infection, and that the bowel was the greatest repository of endotoxin.  With the use of rhubarb (and other herbs) to remove endotoxin from the bowel, animals infected with a variety of febrile diseases experienced faster resolution (Wenlong, 1994).

• A controlled randomized clinical trial on rats evaluated the effects of rhubarb extract on uremia—the collection of nitrogenous wastes in the blood due to kidney diseases.  The uremia symptoms decreased and other blood markers improved, prompting the researchers to conclude, “both the in vivo and in vitro studies have proved the effectiveness of rhubarb in preventing the progression of chronic renal failure” (Li and Liu, 1991).

• A randomized controlled clinical trial examined the effect of rhubarb extract on patients with terminal end-stage kidney failure.  Blood tests showed a decrease in negative blood markers and an improvement in positive blood markers (albumin, lipoprotein, apolipoproteins) in the test group subjects (Ji et al., 1993).

• According to animal studies, the beneficial effect of rhubarb extract is dose-dependent, and due partially to suppression of swelling in kidney tubular cells (Zheng, 1993).  In a study on diabetic rats with nephropathy, rhubarb extract stopped the swelling (renal hypertrophy) at an early stage, and so may be useful in the early stages of human diabetic kidney disease (Yang and Li, 1993).