Gan Cao (Glycyrrhiza uralensis)

Gan Cao (Glycyrrhiza uralensis) is not typically consumed as a macronutrient source but is valued for its dense bioactive compound profile. Key constituents include: Triterpenoid saponins: Glycyrrhizin (also called glycyrrhizic acid), 2–14% of dried root by weight, the principal sweet-tasting compound and primary bioactive; metabolized in the gut to glycyrrhetinic acid (18β-glycyrrhetinic acid), which has significantly higher bioavailability than the parent glycoside. Flavonoids and isoflavonoids: Liquiritin (0.5–1.5%), liquiritigenin (aglycone form, more bioavailable), isoliquiritigenin (a chalcone, ~0.1–0.5%), licoricidin, glabridin (~0.08–0.35%, more concentrated in G. glabra but present in G. uralensis), and formononetin. Total flavonoid content approximately 1.5–4% of dried root. Coumarins: Glycycoumarin, licopyranocoumarin (trace to ~0.05%). Polysaccharides: Glycyrrhiza polysaccharides (GPS), approximately 5–10% of dried root, exhibiting immunomodulatory activity. Other bioactives: Glycyrol, licochalcone A–E (licochalcone A ~0.02–0.1%, noted for anti-inflammatory and antimicrobial properties), and various phenolic acids including ferulic acid and hydroxycinnamic acid derivatives. Minerals (per 100 g dried root, approximate): Potassium (500–800 mg), calcium (150–300 mg), magnesium (50–120 mg), iron (5–15 mg), zinc (2–5 mg), manganese (1–3 mg), with trace amounts of selenium and chromium. Vitamins: Small amounts of B-vitamins (B1, B2, B6) and vitamin E (tocopherols), though concentrations are not pharmacologically significant. Fiber: Crude fiber content approximately 15–25% of dried root, consisting largely of cellulose and hemicellulose. Protein: Approximately 3–6% crude protein. Carbohydrates: Approximately 40–55% total carbohydrates (including polysaccharides and simple sugars such as glucose and sucrose, contributing to the root's natural sweetness alongside glycyrrhizin, which is ~50× sweeter than sucrose). Bioavailability notes: Glycyrrhizin itself has relatively low oral bioavailability (~1–5%) but is extensively hydrolyzed by intestinal bacteria to 18β-glycyrrhetinic acid, which is well absorbed (bioavailability ~50–80%) and is considered the primary systemically active metabolite. Flavonoid glycosides (e.g., liquiritin) require deglycosylation for optimal absorption; their aglycones (e.g., liquiritigenin) show markedly improved bioavailability. Co-administration with other herbs in traditional formulas (as is standard in TCM practice) may enhance or modulate absorption — for instance, pairing with ginger or jujube may improve gastrointestinal absorption. Glabridin has limited oral bioavailability due to extensive first-pass metabolism but shows good absorption when delivered via lipid-based carriers. The polysaccharide fraction is not absorbed intact but exerts immunomodulatory effects primarily through interaction with gut-associated lymphoid tissue (GALT) and modulation of gut microbiota.