Lentinan (Shiitake Beta-Glucan)

Lentinan is a high-molecular-weight β-(1→3)-D-glucan with β-(1→6) branching, isolated from the fruiting bodies and mycelium of Lentinula edodes (Shiitake mushroom). As a purified polysaccharide, its nutritional profile is centered on its bioactive carbohydrate structure rather than broad macronutrient content. Key details: **Bioactive Compound:** β-(1,3)-(1,6)-D-glucan (lentinan), typically comprising 1–2% of dried shiitake mushroom weight (~10–20 mg per gram of dried fruiting body). Purified pharmaceutical-grade lentinan is administered at doses of 1–10 mg (injectable) or 100–500 mg orally as a dietary supplement. **Molecular Weight:** Approximately 400,000–800,000 Da in its native triple-helix conformation, which is critical for biological activity. **Macronutrient Context (whole dried shiitake per 100 g):** Protein ~10–18 g, Fat ~1–2 g, Total dietary fiber ~25–45 g (of which soluble β-glucans constitute approximately 2–5 g), Carbohydrates ~60–75 g, Energy ~270–300 kcal. **Micronutrients (whole shiitake context):** Vitamin D2 (ergocalciferol) ~0.4–46 µg/100 g (highly variable, increases dramatically with UV exposure to >1000 IU/100 g), B-vitamins including niacin (B3) ~14 mg, pantothenic acid (B5) ~22 mg, riboflavin (B2) ~1.3 mg, thiamine (B1) ~0.3 mg per 100 g dried. Minerals: Selenium ~6–46 µg, Copper ~0.9–5.0 mg, Zinc ~1–8 mg, Manganese ~0.8–2.0 mg, Potassium ~1500–1800 mg, Phosphorus ~280–400 mg, Iron ~1–5 mg per 100 g dried. **Additional Bioactives:** Eritadenine (~50–70 mg/100 g dried, cholesterol-lowering compound), ergothioneine (~1–5 mg/100 g, antioxidant amino acid), lenthionine (volatile sulfur compound responsible for flavor and mild antimicrobial effects), ergosterol (provitamin D2, ~50–100 mg/100 g dried). **Bioavailability Notes:** Oral bioavailability of lentinan is relatively low (~1–5%) due to its large molecular weight and degradation in the GI tract; however, gut-associated lymphoid tissue (GALT) interaction mediates significant immunomodulatory effects even with oral dosing. Micronization and particulate formulations improve absorption. The triple-helix conformation is essential for receptor binding (Dectin-1, CR3/complement receptor 3 on macrophages); denaturation reduces bioactivity. Co-administration with vitamin C or acidic environments may partially degrade the helix. Whole mushroom matrix consumption enhances bioavailability of associated micronutrients (e.g., vitamin D2 absorption improved with dietary fat). Eritadenine is well-absorbed orally with direct hepatic cholesterol-lowering action.