Rhubarb and Oxalosis (Rheum Species)
Section snippets
History
Although the petioles of rhubarb leaves have been a food source in modern times, the dried root or rhizome has been used as a medicinal herb since the third millennium BC. Chinese rhubarb is a traditional herb used as a purgative and bacteriocidal agent for dysentery.1 In the 16th and 17th centuries, Chinese rhubarb was coveted as a medicinal remedy that was superior to European varieties. During this time, Russian sources (the Commerce Collegium in St. Petersburg, the Rhubarb Commission on the
Botanical Description
Species in the oxalate-containing genus Rheum include Rheum officinale Baillon (Chinese rhubarb), Rheum palmatum L. (Turkey rhubarb), Rheum rhabarbarum L. (garden rhubarb), and Rheum rhaponticum L. (false rhubarb). Other plant species that contain substantial quantities of oxalate include Halogeton glomeratus (Bieb.) C. A. Mey. (barilla, saltlover), Oxalis caerulea (Small) R. Knuth (blue woodsorrel), Oxalis corniculata L. (creeping oxalis, creeping woodsorrel, yellow oxalis), Portulaca oleracea
Exposure
The leaf petioles (stalks) are used as a vegetable and a constituent of pies. The dried roots have been used medicinally as a cathartic and as a tonic.5, 6 In traditional Chinese medicine, official rhubarb (dahuang) is a purgative and detoxicant used to treat fever, constipation, cancer, abdominal distention and obstruction, jaundice, hematemesis, appendicitis, amenorrhea, skin lesions, food poisoning, inflammation, hypertension, and renal failure.7, 8 The official Chinese herbal medicine
Structure and Properties
Salts of oxalic acid are the main toxic constituents in rhubarb. This chemical is the simplest dicarboxylic acid [(COOH)2] and oxalic acid forms soluble (iron, lithium, potassium, sodium) and insoluble (calcium, magnesium) salts. Boiling spinach for 1 minute removes only about 10% of the insoluble oxalate salts compared with 47% of the soluble oxalate salts.9 Cooking does not substantially alter the oxalate concentration in rhubarb. Roots of some species of rhubarb (R. palmatum L.) contain up
Dose Response
The ingestion of small amounts of plant parts containing oxalates usually causes only mild gastrointestinal irritation. Serious intoxication from the ingestion of rhubarb leaf is not well-documented in the modern medical literature. Fatalities associated with the ingestion of rhubarb probably involved other agents, toxins, or etiologies. The intravenous injection of 20 mg sodium oxalate/kg produced profound hypocalcemia and cardiac arrest.21
Toxicokinetics
Gastrointestinal absorption of oxalate occurs in the small intestine by active transport and by passive diffusion along the small intestine and the colon. The bioavailability of oxalate is low (<2-6% as total oxalate) and varies with plant species.15 In a study of volunteers, the average bioavailability of oxalate in sugar beets and spinach was 0.7% and 4.5%, respectively.22 The mean bioavailability of a solution of sodium (soluble) oxalate in the same study was 6.2%. Endogenous intermediary
Clinical Response
Most casual exposures of children to the rhubarb plant produce mild gastrointestinal symptoms (vomiting, diarrhea) that resolve within a few hours.24 The initial symptoms of oxalate intoxication result from irritation of the oropharynx and the gastrointestinal tract manifest by sore throat, dysphagia, nausea, vomiting, anorexia, diarrhea, abdominal pain, and occasionally hematemesis. Symptoms typically begin within 2-12 hours after ingestion.14 Serious oxalate toxicity produces renal
Analytical Methods
Methods for detecting anthraquinone derivatives in rhubarb include thin layer chromatography,32 capillary electrophoresis,33 high performance liquid chromatography (HPLC),34 high speed counter-current chromatography,10 high performance liquid chromatography with ultraviolet detection and mass spectrometry,35 and HPLC coupled with electrospray ionization mass spectrometry.17 HPLC with mobile phase gradient conditions and UV detection (280 nm) can detect at least 30 compounds in rhubarb at
Decontamination
Decontamination is not usually necessary following the ingestion of oxalate-containing plant parts. Symptomatic treatment for pharyngeal irritation includes demulcents (milk, chipped ice) and antihistamines. For serious oxalate ingestions, lavage with 0.15% calcium hydroxide (lime water) to precipitate insoluble calcium oxalate in the gastrointestinal tract was a previously recommended treatment for patients presenting to a health care facility within 1 hour of ingestion, but there are no
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2023, Journal of the Taiwan Institute of Chemical EngineersNephroprotective and nephrotoxic effects of Rhubarb and their molecular mechanisms
2023, Biomedicine and PharmacotherapyEpigenetic changes in inflammatory genes and the protective effect of cooked rhubarb on pancreatic tissue of rats with chronic alcohol exposure
2022, Biomedicine and PharmacotherapyCitation Excerpt :Ren et al. reported that chronic plus binge alcohol exposure could cause more stress to the endoplasmic reticulum, oxidative stress, and inflammation, leading to pancreatic injury[31]. Rhubarb has been a commonly used and important herb in Chinese medicine since the third millennium BCE [32]. Modern research shows that rhubarb has extensive pharmacological activities, such as gastrointestinal regulation, antimicrobial and anti-inflammatory effects, and cardiovascular protection.[33].
Complete heart block without ventricular escape secondary to hyperkalemia induced by herbal tea
2022, HeartRhythm Case ReportsCitation Excerpt :When considering the other ingredients, his gallon of herbal tea equaled 55 mEq of potassium.8 To add insult to injury, Indian rhubarb has an abundance of oxalates and anthraquinones, which has been reported to be directly nephrotoxic.9,10 His hyperkalemia ultimately precipitated complete heart block without a ventricular escape.
Oxalate bioaccessibility in raw and cooked rhubarb (Rheum Rhabarbarum L.) during in vitro digestion
2020, Journal of Food Composition and AnalysisCitation Excerpt :It has also been reported to have a positive impact on hepatic inflammation induced by acute alcohol intakes (Neyrinck et al., 2017) and shown promising anti-cancer properties (Huang et al., 2006). However, many publications and cookbook advise that rhubarb should not be consumed regularly as it contains high levels of oxalates in the petioles which if consumed regularly, could cause kidney stone formation (Donald, 2009; Nguyễn and Savage, 2013a; Crews and Clarke, 2014). Oxalates are considered as end products in mammalian metabolism existing as water soluble forms with Na+, K+ or water insoluble forms with Ca2+, Mg2+ in which calcium oxalate is the most common constituent of kidney stones (Nguyễn et al., 2018).
This article was published in: Barceloux DG. Medical Toxicology of Natural Substances: Foods, Fungi, Medicinal Herbs, Toxic Plants, and Venomous Animals. Hoboken, NJ: John Wiley & Sons, 2008. pp. 84-88. Copyright © 2008 by John Wiley & Sons, Inc. Reprinted with permission of John Wiley & Sons, Inc.