Insoluble fibers

Macronutrients

Cellulose and lignin: the fiber that hardly ferments. It makes bulk and speeds up transit.

It is the skin, the husk and the strings. Peeling a vegetable, sifting a flour or straining a juice removes them — that is the whole difference between a fruit and its juice.

Effects and benefits

The fiber that hardly ferments but provides all the bulk: the cellulose and lignin of bran, skins and husks. Wheat bran fiber speeds up transit and increases stool bulk; all of them fill the plate without a single calorie.

Cellulose is the most abundant organic molecule on the planet, and we cannot digest it: it would take a cellulase, which only a few microbes have. It therefore crosses the gut almost intact, holding water, which gives bulk to stools and speeds their passage.

Wheat bran fiber contributes to an acceleration of intestinal transit, from 10 g a day, and to an increase in fecal bulk (Regulation 432/2012).

The benchmarks: EFSA considers 25 g of fiber a day enough for normal bowel function in adults; ANSES aims for 30 g. French adults eat about 20 g (ANSES, INCA 3, 2017).

By age: EFSA proposes 10 g a day from age one, rising with age to the adult's 25 g. Transit often slows over the years; fiber, with enough water, is then a simple help.

Sources: EU Regulation 432/2012 · EFSA, 2010 · ANSES, 2016 · ANSES, INCA 3, 2017

Insoluble fibers

Effects and benefits

Where to find it (54)

Also, in smaller amounts (810)