Dietary Fiber

Dietary fiber earns at because it delivers a broad cluster of cardiometabolic and gut benefits, backed by mortality evidence, at food-grade safety and near-zero cost. The practical verdict: if you eat well under the 25 to 38 gram target, which is most people, raising fiber intake is one of the highest-value, lowest-risk changes available, best done food-first with a viscous supplement like psyllium added for a specific LDL or regularity goal. Raise intake gradually with fluid, and if fermentable fibers upset your gut, switch to psyllium. The score tier is justified by the depth of the evidence base and the benign risk profile, held just short of top-tier because much of the mortality data is observational and per-person effects depend on your starting point.

✅ Best for: People eating well under the daily fiber target who want a cheap, evidence-backed lever on long-term risk; people with elevated LDL who want a food-grade adjunct, given the psyllium and beta-glucan lipid data in Jovanovski 2018; people with prediabetes or a family history of type 2 diabetes, where cereal fiber shows the strongest signal; people with constipation who want a non-stimulant fix; and measurement-minded people who will raise viscous fiber, hold it 8 weeks, and recheck LDL and fasting glucose.

❌ Avoid if: You have a bowel stricture, a prior obstruction, gastroparesis, or difficulty swallowing, where bulk fiber can lodge and block and needs clinician guidance; you are in an active IBS flare and reacting to fermentable fructans, in which case psyllium is the safer fiber; or you cannot take bulk fiber with adequate fluid. Anyone on oral medications should separate them from viscous fiber by 2 to 4 hours to avoid slowing drug absorption.