Fibre: Why It Matters for Your Diet

Fibre is the part of plant food that passes through the small intestine largely undigested. That sounds unremarkable, and it is exactly why it matters: fibre changes how food moves, how full you feel, and what happens in the large intestine.

Two broad types

• Soluble fibre — oats, barley, legumes, apples, citrus — forms a gel that slows digestion and is fermented by gut bacteria.
• Insoluble fibre — wheat bran, whole grains, vegetable skins, nuts — adds bulk and supports regularity.

What the evidence supports

Higher dietary fibre intake is consistently associated with lower risk of cardiovascular disease, type 2 diabetes, and colorectal cancer in large observational studies and pooled analyses. These are associations from dietary patterns rather than proof that fibre alone is responsible, but the direction is unusually consistent and public health bodies treat it as a firm recommendation.

Practical ways to add fibre

• Add half a tin of lentils or beans to a soup, sauce, or salad.
• Choose oats over low-fibre cereals at breakfast.
• Leave skins on potatoes, apples, and pears.
• Keep frozen vegetables to hand and add a handful to whatever is cooking.
• Use nuts or seeds as a topping rather than an occasional snack.

Increase gradually

A sudden jump in fibre commonly causes bloating and wind. Add one source at a time over a couple of weeks, and increase fluids alongside it.