{
  "dataset": "fiber-types-compared",
  "title": "Fiber Types Compared — psyllium, inulin, methylcellulose, wheat dextrin, beta-glucan, acacia, glucomannan, PHGG",
  "sourcePage": "https://verifiedsupplementdata.com/fiber/forms-compared/",
  "license": "CC BY 4.0",
  "licenseUrl": "https://creativecommons.org/licenses/by/4.0/",
  "attribution": "Verified Supplement Data (2026), Fiber Types Comparison",
  "dateModified": "2026-07-13",
  "methodology": "Qualitative comparison of common supplemental fiber types by solubility, viscosity (gel-forming), fermentability (gas profile), best-evidenced use, and who should avoid each. Attributes trace to systematic reviews and the physics-of-fiber literature (McRorie & McKeown 2017; NCBI-verified citations on the source page). The key principle: fiber effects are type-specific, so the type matters more than the total gram count.",
  "forms": [
    {
      "form": "Psyllium husk",
      "solubility": "Mostly soluble",
      "viscous": "Yes — gels",
      "fermentable": "Low (survives the colon)",
      "bestFor": "Constipation, cholesterol (FDA claim), IBS",
      "avoid": "Esophageal narrowing/dysphagia; low fluid intake",
      "evidence": "The best-evidenced fiber: FDA heart-health claim at 7 g/day soluble, plus RCT support for constipation and IBS. Gels and holds water without much gas because it is barely fermented."
    },
    {
      "form": "Inulin / FOS (chicory)",
      "solubility": "Soluble",
      "viscous": "No",
      "fermentable": "High + fast (most gas)",
      "bestFor": "Feeding gut bacteria (prebiotic)",
      "avoid": "IBS, SIBO, FODMAP sensitivity",
      "evidence": "A prebiotic — reliably raises Bifidobacterium — but a fructan, so it is a core IBS trigger. It adds no mechanical bulk, so it is not a reliable constipation treatment."
    },
    {
      "form": "Methylcellulose (Citrucel)",
      "solubility": "Soluble",
      "viscous": "Yes — gels",
      "fermentable": "None (not fermented)",
      "bestFor": "Constipation with the least gas",
      "avoid": "Anyone wanting a prebiotic effect (there is none)",
      "evidence": "Gels and bulks like psyllium but is not fermented at all, so it produces little gas. It is NOT a prebiotic. Thinner trial evidence than psyllium."
    },
    {
      "form": "Wheat dextrin (Benefiber)",
      "solubility": "Soluble",
      "viscous": "No",
      "fermentable": "Moderate (less gas than inulin)",
      "bestFor": "Adding fiber invisibly (dissolves clear)",
      "avoid": "Relying on it to relieve constipation",
      "evidence": "Dissolves clear and tasteless with a milder gas profile than inulin, but being non-viscous it is a weak laxative — not interchangeable with psyllium."
    },
    {
      "form": "Beta-glucan (oat/barley)",
      "solubility": "Soluble",
      "viscous": "Yes — gels",
      "fermentable": "Fermentable",
      "bestFor": "Cholesterol, post-meal blood sugar",
      "avoid": "Celiac (use certified gluten-free oats)",
      "evidence": "Viscous gel lowers LDL cholesterol at ~3 g/day (its own FDA claim family) and blunts post-meal glucose. Usually eaten as oats rather than a supplement."
    },
    {
      "form": "Acacia / gum arabic",
      "solubility": "Soluble",
      "viscous": "No (stays thin)",
      "fermentable": "Slow + distal (best tolerated)",
      "bestFor": "A gentle prebiotic at higher doses",
      "avoid": "Expecting proven weight/lipid outcomes",
      "evidence": "The best-tolerated fermentable fiber — feeds bacteria like inulin but with far less gas. Human outcome data beyond tolerability is still thin."
    },
    {
      "form": "Glucomannan (konjac)",
      "solubility": "Soluble",
      "viscous": "Very — most gel-forming",
      "fermentable": "Slow",
      "bestFor": "Modest short-term weight/LDL support",
      "avoid": "Swallowing trouble; tablets dry — choking/obstruction risk",
      "evidence": "The most viscous common fiber and the one with a real safety flag: taken dry it can swell and block the throat or gut. Always take with a full glass of water. Weight effect is modest."
    },
    {
      "form": "PHGG (guar gum, partially hydrolyzed)",
      "solubility": "Soluble",
      "viscous": "No",
      "fermentable": "Gentle (low gas)",
      "bestFor": "Bloating in IBS",
      "avoid": "Expecting a global IBS cure",
      "evidence": "A well-tolerated prebiotic-type fiber; a 12-week RCT improved bloating specifically in IBS, though not overall IBS severity or quality of life."
    }
  ]
}