Prebiotics

Prebiotics are non‑digestible food components—primarily certain soluble fibers—that resist digestion in the upper gastrointestinal tract and are selectively fermented by beneficial gut microbes. Their primary purpose is to nourish beneficial bacteria (e.g., Bifidobacterium and Lactobacillus) and thereby promote a healthier intestinal ecosystem, which in turn influences host metabolism, immunity, and even brain function.

• Oligosaccharides and Polysaccharides: Prebiotics are a heterogeneous class of oligosaccharides and polysaccharides.
• Inulin: The most studied, inulin, is a β‑(2→1)‑linked fructan with the general formula (C₆H₁₀O₅)ₙ + C₆H₁₂O₆ (terminal glucose). Its IUPAC name is (2‑β‑D‑fructofuranosyl)ₙ‑D‑glucose (n ≈ 2–60).
• Fructooligosaccharides (FOS): Shorter chains (DP = 3–10) with the same β‑(2→1) linkages.
• Galactooligosaccharides (GOS): Consist of β‑(1→4) and β‑(1→6) linked galactose units with a terminal glucose.
• Solubility and Properties: All are highly soluble, low‑molecular‑weight (≈ 1–5 kDa), and resistant to α‑amylase, but readily fermentable by colonic microbes.
• Water Binding: Their high water‑binding capacity (≈ 1 g water per 1 g polymer) contributes to stool bulking.

• Plant Sources: Commercial prebiotics are primarily derived from plant tubers and legumes: inulin from chicory (Cichorium intybus) root, Jerusalem artichoke (Helianthus tuberosus), and agave; FOS from sugar beet and corn; GOS from lactose‑derived enzymatic trans‑glycosylation of whey.
• Extraction Process: Extraction typically involves hot‑water extraction, filtration, and spray-drying, followed by purification steps (e.g., ion-exchange chromatography) to achieve ≥ 90 % purity.
• Quality Metrics: Quality metrics include degree of polymerization (DP) distribution, absence of residual solvents, and microbial safety (≤ 10 CFU g⁻¹ of pathogens).
• GMP-Grade Products: Certified “GMP‑grade” prebiotic powders should display low ash content (< 1 %) and a defined DP range, ensuring consistent fermentability and reproducible clinical outcomes.