Dietary fiber is one of the most evidence-backed supplements for metabolic and digestive health. Only 5% of Americans meet the recommended 25-38g/day, making it the largest nutrient gap in Western diets. Our research shows psyllium husk is the gold standard with evidence for LDL cholesterol reduction (7% at 10g/day), blood sugar control, and constipation relief. The FDA authorized a heart health claim for psyllium. Soluble fiber (psyllium, beta-glucan) has the strongest clinical data; insoluble fiber (wheat bran) primarily affects bowel regularity.
Soluble fiber (psyllium, beta-glucan, guar gum) forms a gel in the gut that: (1) traps bile acids, forcing the liver to pull cholesterol from blood to make new bile → LDL reduction; (2) slows gastric emptying and glucose absorption → blunted blood sugar spikes; (3) increases satiety via stretch receptors and GLP-1 release; (4) is fermented by gut bacteria into short-chain fatty acids (SCFAs) that feed colonocytes and reduce inflammation. Insoluble fiber (wheat bran, cellulose) adds bulk to stool and speeds transit time. Prebiotic fibers (inulin, FOS) specifically feed beneficial bacteria like Bifidobacterium and Lactobacillus.
Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated:
Not medical advice. Based on published clinical research and systematic reviews.