Dietary fibers (DF)

Dietary fibers are a collective term used to identify various polysaccharides and lignin (not all dietary fibers are plant polysaccharides) fractions of foods that are not hydrolyzed by the enzymes of the digestive system, but that are, or might be, hydrolyzed by gut microbiota

They consist of non-starch polysaccharides like cellulose, hemicellulose, pectin, beta-glucans, resistant starches, and lignin. They also include low-molecular-weight non-digestible oligosaccharides such as fructooligosaccharides (FOSs), Galacto-oligosaccharides (GOS), xylooligosaccharides (XOSs), and inulin
Shen et al. 2023 Nutrients 15(15): 3321

Dietary fiber and whole grains are rich in a unique blend of bioactive components, such as resistant starches, vitamins, minerals, phytochemicals, and antioxidants. This composition has sparked significant research interest over the past few decades due to their potential health benefits. Epidemiological and clinical studies consistently show an inverse relationship between the intake of dietary fiber and whole grains and the prevalence of obesity, type 2 diabetes, cancer, and cardiovascular disease (CVD).
Lattimer & Haub 2010 Nutrients 2: 1266–1289

Key fiber types include:

• Arabinoxylan


• Inulin


• Pectin


• Bran


• Cellulose


• Beta-glucan


• Resistant starch

Lattimer & Haub 2010 Nutrients 2: 1266–1289

These fibers may affect:

• Intestinal viscosity


• Nutrient absorption


• Passage rate


• Short-chain fatty acid production


• Gut hormone production

Lattimer & Haub 2010 Nutrients 2: 1266–1289

Dietary fibre consists of plant substances that resist hydrolysis by small bowel digestive enzymes and is an extremely complex group of substances.
James et al. 2003 Intern Med J 33(7):291-296

Shown is the effect of soluble, Insoluble dietary fibers (DF) and their combination in the different sections of the intestine (stomach, small intestine, proximal colon, distal colon).
Water-soluble dietary Fibers (DF) mean e.g., guar gum, oat bran, pectins, psyllium, legumes, mucilages, resistant starch. The final effects are bulking and gas production.
Insoluble dietary fibers (DF) mean e.g., Karaya gum, lignin, Methyl cellulose, Wheat-bran. The final effects are bulking, decrease of transit, absorbing of nutrients and water.
Their combination means e.g., wheat-bran + resistant starch, Barley (Hordeum vulgare) Bran, psyllium + resistant starch (Nucolox TM). The final effects are bulking, decrease of transit, decrease of pH and phenols, increase of SCFAs, gas production and absorbing nutrients and water.
(according to James et al. 2003 Intern Med J 33(7):291-296)

Found in plant-based foods like fruits , vegetables , whole grains , legumes , nuts , and seeds

Dietary fiber can be used to influence dysbiosis. For example, the Short-Chain Fatty Acids (SCFAs)-Producing Bacteria are promoted.

Components of dietary fiber according to the American Association of Cereal Chemists are:

• Insoluble dietary fibers (DF)


• Water-soluble dietary Fibers (DF)


• Fructans


• Fructooligosaccharides (FOS)


• Galactooligosaccharides (GOS)


• Phytin / Phytic Acid / Phytate (Inositol Hexakisphosphate)


• Tannin

Jones 2001 Cereal Foods World 46(3): 112

see also:
Cholesterol-lowering Effect