Rhubarb (Rheum rhabarbarum)

Rhubarb (Rheum rhabarbarum) contains bioactive anthraquinones including rhein and emodin that modulate inflammatory pathways and estrogen receptor activity. Clinical studies demonstrate significant anti-inflammatory effects in sepsis and menopausal symptom relief.

Origin & History

Rhubarb (Rheum rhabarbarum) is a perennial herbaceous plant in the Polygonaceae family, native to Siberia and widely cultivated globally for its edible petioles and medicinal roots/rhizomes. The medicinal parts are primarily extracted from roots and petioles using solvents like ethanol or water to yield crude extracts or isolated compounds such as stilbenes and anthraquinones.

Historical & Cultural Context

In Traditional Chinese Medicine, rhubarb roots and rhizomes have been used for over 2,000 years as a purgative, anti-inflammatory, and detoxifier for constipation, sepsis-like syndromes, and inflammation. Historical records also document rhubarb use in Japan since ancient times for similar gastrointestinal and febrile conditions.

Health Benefits

• Reduces systemic inflammation markers: Meta-analysis of 15 RCTs (n=869) showed significant reduction in IL-6 and TNF-α in sepsis patients (Strong evidence)
• Alleviates menopausal symptoms: Standardized root extract ERr 731® demonstrated efficacy across multiple trials in menopausal women (Moderate evidence)
• Improves gastrointestinal dysfunction: Reduced GI dysfunction by 72% (RR 0.28) in critically ill patients (Strong evidence)
• Anti-inflammatory effects: Inhibits COX-2 expression and reduces cytokine release at 5 µg/mL in cell studies (Preliminary evidence)
• Supports platelet function: Increased platelet count by 58.16 in sepsis patients (Strong evidence)

How It Works

Rhubarb's anthraquinone compounds (rhein, emodin, aloe-emodin) inhibit NF-κB signaling pathway, reducing pro-inflammatory cytokine production including IL-6 and TNF-α. The standardized extract ERr 731® demonstrates selective estrogen receptor modulator (SERM) activity, binding to estrogen receptors to alleviate menopausal symptoms. These compounds also modulate gut microbiota and enhance intestinal barrier function through anti-inflammatory mechanisms.

Scientific Research

A meta-analysis of 15 RCTs (n=869 patients with systemic inflammation/sepsis) found adjuvant crude rhubarb significantly reduced inflammatory markers IL-6 (SMD -1.30) and TNF-α (SMD -0.95), while improving gastrointestinal dysfunction (RR 0.28) (PMID: 25617260). Standardized Rheum rhaponticum root extract (ERr 731®) showed efficacy for menopausal symptoms across multiple trials, though specific sample sizes were not detailed.

Clinical Summary

A meta-analysis of 15 randomized controlled trials (n=869) demonstrated significant reduction in IL-6 and TNF-α inflammatory markers in sepsis patients treated with rhubarb extracts. Multiple clinical trials using standardized ERr 731® extract showed moderate evidence for reducing menopausal hot flashes, night sweats, and mood symptoms. Most studies used dosages ranging from 4-12mg daily of standardized extract. Evidence quality is strong for anti-inflammatory effects but moderate for menopausal applications due to varying study designs.

Nutritional Profile

**Macronutrients (per 100g raw stalks):** Energy: 21 kcal; Carbohydrates: 4.5g (including 1.1g sugars); Dietary fiber: 1.8g; Protein: 0.9g; Fat: 0.2g. **Key Micronutrients:** Vitamin K1: 29.3 µg (24% DV); Vitamin C: 8 mg (9% DV); Calcium: 86 mg (7% DV, though bioavailability is significantly reduced due to oxalic acid chelation — estimated 5–10% absorption vs. ~30% from dairy); Potassium: 288 mg (6% DV); Manganese: 0.20 mg (9% DV); Magnesium: 12 mg; Phosphorus: 14 mg; Iron: 0.22 mg (bioavailability low due to oxalate binding). **Bioactive Compounds:** Oxalic acid: 570–1,900 mg/100g (predominantly in leaves; stalks contain lower but still significant levels; limits mineral absorption and poses risk for kidney stone–prone individuals); **Anthraquinone glycosides (concentrated in root/rhizome):** Emodin: 0.3–2.5% dry weight of root; Rhein: 0.5–3.0% dry weight of root; Chrysophanol: 0.2–1.5% dry weight of root; Aloe-emodin: 0.1–0.8% dry weight of root; Sennosides A & B: present in root, responsible for cathartic/laxative activity; **Stilbenes:** Rhaponticin (rhapontin): 2–6% dry weight of root (the primary active in ERr 731® extract, acts as a selective estrogen receptor modulator — phytoestrogen activity); Desoxyrhaponticin: 0.5–2% dry weight of root; Resveratrol and trans-resveratrol: trace to minor amounts; **Tannins:** Gallotannins and catechins: 5–10% dry weight of root (contribute to astringent and anti-inflammatory properties); **Polyphenols/Flavonoids:** Catechin, epicatechin, quercetin glycosides present in stalks and root; total phenolic content in stalks: ~100–250 mg GAE/100g fresh weight; anthocyanins (cyanidin-3-glucoside, cyanidin-3-rutinoside) in red-pigmented stalks: up to 2,000 µg/100g. **Polysaccharides (root):** Acidic polysaccharides and pectins contributing to prebiotic and immunomodulatory effects. **Bioavailability Notes:** Anthraquinone glycosides are prodrugs — hydrolyzed by gut microbiota to active aglycones (emodin, rhein, chrysophanol) in the colon, which accounts for the 6–10 hour onset of laxative effect; Rhein achieves peak plasma concentration 1–2 hours after oral dosing of processed rhubarb root and has the highest systemic bioavailability among the anthraquinones (~30–40% after glucuronidation); Rhaponticin is hydrolyzed to rhapontigenin by intestinal glucosidases, with moderate oral bioavailability (~20–35%); high oxalate content substantially reduces calcium and iron bioavailability from the plant itself.

Preparation & Dosage

Clinically studied dosages include crude rhubarb extract at unspecified daily amounts as adjuvant therapy for sepsis, and ERr 731® standardized root extract at 4 mg/day for menopausal symptoms. Preclinical studies used extracts at 1-100 µg/mL, with anti-inflammatory effects observed at 5 µg/mL. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Turmeric, Boswellia, Ginger, Probiotics, Green Tea Extract

Safety & Interactions

Rhubarb supplements may cause gastrointestinal side effects including diarrhea, abdominal cramping, and nausea, particularly at higher doses. The anthraquinone content can interact with cardiac glycosides, anticoagulants, and diuretics by affecting electrolyte balance and drug absorption. Contraindicated in pregnancy, breastfeeding, and individuals with kidney stones due to high oxalate content. Long-term use may lead to electrolyte imbalances and dependency for bowel movements.