Last verified: 17 days ago
Fiber
Also known as: dietary fiber, soluble fiber, insoluble fiber, prebiotic fiber, fructo-oligosaccharides, pectin, psyllium, scFOS
Evidence under review. — Not yet rated
Dietary fiber supports gut health, blood sugar, cholesterol, and liver health. Evidence is solid but source matters.
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What it does
Dietary fiber is the indigestible part of plant foods that passes through your digestive system largely intact. It feeds beneficial gut bacteria, which produce short-chain fatty acids (SCFAs) that...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
No established dose from provided studies
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Found in
IM8 Daily Ultimate Essentials Pro, AG1 (Athletic Greens), Poppi Cherry Limeade and 17 more
What the Science Says
Dietary fiber is the indigestible part of plant foods that passes through your digestive system largely intact. It feeds beneficial gut bacteria, which produce short-chain fatty acids (SCFAs) that support metabolic and digestive health. Studies in the provided data link higher fiber intake — especially from fruit — to lower cholesterol, better blood sugar control, reduced liver stiffness, and faster healing of anal fissures.
What It Doesn't Do
Won't dramatically change brain activity or food cravings on its own. Fiber supplements alone didn't improve neurocognitive function — that benefit came from the overall diet. Not all fiber sources are equal: total fiber intake showed weaker liver benefits than fruit-specific fiber. Don't expect a single fiber supplement to replace a varied, whole-food diet.
Evidence-Based Benefits
Higher fiber intake is linked to lower LDL and total cholesterol in healthy adults.
Moderate EvidenceEffective at: 40g/day whole food source in one study; no precise supplement dose established
Supporting studies (click to view on PubMed):
Fruit-derived fiber is associated with lower liver stiffness and reduced risk of significant liver fibrosis.
Moderate EvidenceEffective at: No established dose from provided studies
Supporting studies (click to view on PubMed):
A fiber-rich diet with psyllium speeds up healing of acute anal fissures and reduces pain.
Moderate EvidenceEffective at: Fiber-rich diet plus psyllium (exact dose not specified in study)
Supporting studies (click to view on PubMed):
Fermentable fibers like scFOS stimulate beneficial gut bacteria and increase short-chain fatty acid production.
Moderate EvidenceEffective at: No established dose from provided studies
Supporting studies (click to view on PubMed):
Replacing refined flour with higher-fiber alternatives improves blood sugar response after meals.
Weak EvidenceEffective at: No established dose from provided studies
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Variable — soluble fiber (pectin, scFOS) is fermented in the colon and produces SCFAs; insoluble fiber passes through largely intact. Fermentable fibers have the most documented metabolic effects.
Red Flags to Watch For
- Fiber source matters: fruit-derived fiber showed liver benefits in the data, but grain, vegetable, and legume fiber did not show the same consistent effect
- Fiber supplements (e.g., maltodextrin placebo comparisons) may not replicate whole-food fiber benefits
- High-dose fiber supplementation can cause bloating, gas, or GI discomfort, especially when introduced rapidly
- Products marketing fiber for brain health or weight loss should be viewed skeptically — the provided RCT found no significant effect of fiber supplementation on food-reward brain activity
Products Containing Fiber
See how Fiber is used in these analyzed products:
IM8 Daily Ultimate Essentials Pro
Supplement
AG1 (Athletic Greens)
Supplement
Poppi Cherry Limeade
Supplement
1st Phorm Opti-Greens 50
310 Greens - Mixed Berry
Supplement
Physician's Choice 15 Billion Probiotic
Supplement
Garden of Life Vitamin Code Men's Multi
BioGaia Gastrus IBS
Supplement
SlimFast High Protein Shakes
Weight Loss
Maximum Vibrance
Supplement
Navitas Organics Superfood+ Digestive Blend
Supplement
Host Defense Mushroom Powders
Supplement
Snap Supplements Irish Sea Moss
Supplement
Rise Bar - Almond Honey Protein Bars
Supplement
Balance of Nature Fruits & Veggies
Supplement
Solaray Bean Enzyme 30 GaIU
Supplement
310 Nutrition Vanilla Crème Shake
Supplement
Zena Nutrition Organic Super Greens Powder
Supplement
ColonBroom
Supplement
Physician's Choice Digestive Enzymes
Supplement
Frequently Asked Questions
What does Fiber do?
Dietary fiber supports gut health, blood sugar, cholesterol, and liver health. Evidence is solid but source matters.
What is the effective dose of Fiber?
No established dose from provided studies
Is Fiber safe?
Fiber source matters: fruit-derived fiber showed liver benefits in the data, but grain, vegetable, and legume fiber did not show the same consistent effect
What doesn't Fiber do?
Won't dramatically change brain activity or food cravings on its own.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25