Fibre is the part of plant food your gut cannot digest. It softens digestion, feeds helpful gut bacteria and slows how fast sugar reaches your blood. Most adults eat far less of it than the amount linked to the lowest risk of early death. Fixing that costs almost nothing.
A 2019 series of systematic reviews in The Lancet pooled 185 prospective studies and dozens of controlled trials and found 15 to 30 percent lower rates of death from any cause, coronary heart disease, type 2 diabetes and colorectal cancer among the highest-fibre eaters, with benefit still rising near 29 g a day (Reynolds et al.). Controlled feeding trials in the same series showed cereal fibre and whole grains lower LDL cholesterol, blood pressure and after-meal glucose, which gives the observational signal a plausible mechanism. The World Health Organization's healthy diet guidance puts fibre-rich foods at the core of its advice. Why this grades strong rather than moderate: the cohort base is enormous and consistent, dose-response is clear, and trials reproduce the intermediate effects. Residual doubt lives in exactly how much of the association is the fibre versus the whole plant-food package, which is why the practice below is about foods rather than powders.
Doing it: Build meals around vegetables, beans, lentils, oats, barley and whole grains until you reach roughly 25 to 29 g of fibre a day. Raise the amount over a few weeks and drink enough water, or bloating will tempt you to quit.
Who it suits: Almost everyone, especially people who eat mostly refined or meat-centred meals, and anyone with raised LDL cholesterol, constipation or prediabetes
Sources
- Reynolds A, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet 2019.
- World Health Organization, Healthy diet fact sheet.
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