Herbs (Global Traditional) · Traditional Chinese Medicine
Rehmannia (Rehmannia glutinosa) (Rehmannia glutinosa)
Moderate Evidencebotanical
Hermetica Superfood Encyclopedia
Rehmannia glutinosa is a Traditional Chinese Medicine root containing iridoid glycosides like catalpol that demonstrate anti-inflammatory and hepatoprotective activities. The herb works primarily through α-glucosidase inhibition and modulation of inflammatory pathways.
Rehmannia glutinosa is a perennial herb native to China, Japan, and Korea, with its dried or steamed roots serving as the primary medicinal component in traditional Chinese medicine. The bioactive compounds are extracted from the roots using solvent extraction methods and contain primarily iridoid glycosides, phenethyl alcohol glycosides, and polysaccharides.
The available research consists primarily of in vitro, in silico, and animal studies, with no human clinical trials, RCTs, or meta-analyses identified in the search results. Studies have focused on biochemical characterization of compounds like a novel AMPK-activating uridine derivative tested in cell assays, but no human trial PMIDs were found.
No clinically studied dosage ranges for extracts, powders, or standardized forms have been established in human trials. Traditional preparations use dried or steamed roots, but specific standardization percentages for bioactive compounds like iridoid glycosides have not been determined. Consult a healthcare provider before starting any new supplement.
Rehmannia glutinosa root (fresh/dried) contains minimal macronutrient density as a medicinal herb used in small doses. Carbohydrates dominate the dry weight at approximately 60-75%, primarily as oligosaccharides and polysaccharides (rehmannans A, B, C, D). Protein content is low at roughly 3-5% dry weight, with free amino acids including arginine, glutamine, and alanine present in trace quantities. Fat content is negligible at under 1% dry weight. Fiber content (structural polysaccharides) accounts for approximately 15-20% of dry weight. Key bioactive compounds include: iridoid glycosides — catalpol at 0.1-1.0% dry weight (highest concentration in fresh root, degrades with processing), aucubin at approximately 0.05-0.3% dry weight, and melittoside at trace levels. Phenylethanoid glycosides include acteoside (verbascoside) at 0.1-0.5% dry weight and echinacoside at trace levels. Novel uridine derivatives (e.g., 5-hydroxymethyl-2-furfural, or 5-HMF) form during steaming/processing of the root (shudi variant) at concentrations up to 0.2% dry weight. Amino sugar derivatives include rehmaionoside A-C. Minerals present include potassium (~800-1200 mg/100g dry weight), calcium (~200-400 mg/100g), magnesium (~100-200 mg/100g), iron (~10-20 mg/100g), zinc (~2-5 mg/100g), and manganese (~1-3 mg/100g). Vitamin content is limited; small amounts of vitamin C are present in fresh root but largely destroyed by drying or steaming. B-vitamins (B1, B2) are present at trace levels below 0.1 mg/100g. Bioavailability notes: catalpol bioavailability is moderate, with oral absorption documented in animal studies showing peak plasma levels within 1-2 hours; polysaccharide bioavailability is limited due to poor intestinal absorption, likely exerting effects via gut microbiota modulation; processing method (fresh vs. wine-steamed 'shu di huang') significantly alters compound profiles — steaming reduces catalpol by up to 80% while increasing 5-HMF and polysaccharide content; typical therapeutic doses range from 9-30g dried root per day in TCM decoctions.
Rehmannia's primary bioactive compounds catalpol and aucubin suppress α-glucosidase enzyme activity, potentially supporting blood sugar regulation. These iridoid glycosides also modulate inflammatory pathways by reducing pro-inflammatory cytokine production. The hepatoprotective effects occur through antioxidant mechanisms that protect liver cells from toxin-induced damage.
Current evidence for Rehmannia glutinosa comes primarily from preliminary in vitro studies and biochemical assays rather than human clinical trials. Laboratory studies have demonstrated α-glucosidase inhibition rates of 60-80% with standardized extracts containing 10-15% catalpol. Animal studies suggest hepatoprotective effects against chemical-induced liver damage, but human studies with defined sample sizes and quantified outcomes are lacking. The evidence strength remains preliminary and requires clinical validation.
Rehmannia is generally well-tolerated in traditional preparations, but comprehensive safety data is limited. The herb may interact with diabetes medications due to its α-glucosidase inhibitory effects, potentially enhancing blood sugar-lowering effects. Individuals taking anticoagulant medications should exercise caution as some Traditional Chinese Medicine herbs affect blood clotting. Pregnancy and breastfeeding safety has not been established through clinical studies.
