Composition
Chicory root inulin (FOS)
Chicory root inulin is a naturally occurring fibre made of chains of fructose; its shorter chains are called fructooligosaccharides (FOS) or oligofructose.
Also known as: inulin, fructooligosaccharides, FOS, oligofructose, inulin-type fructans (ITF), chicory inulin
What it is
Inulin and fructooligosaccharides (FOS) are inulin-type fructans: chains of fructose units joined by β(2–1) links. The difference is chain length. Oligofructose has roughly 3 to 9 units per chain, while inulin is a mixture of chains with a degree of polymerisation from 2 to 60 or more.[1]
Inulin, FOS and galacto-oligosaccharides are considered accepted prebiotics. A prebiotic is currently defined as “a substrate that is selectively utilized by host microorganisms conferring a health benefit” — in other words, food for gut microbes rather than for the animal directly. For how prebiotics differ from live cultures, see probiotics vs prebiotics for dogs.[1]
Where it’s found
Inulin-type fructans can be derived from chicory root, agave, artichokes and yacon. Fructans from chicory root have a characteristic branching and chain-length profile that differs from those of other plant sources such as agave, and chicory fructans can be prepared as inulin, as oligofructose, or as a mixture of both.[1]
Why it’s used in dog supplements
Cats and dogs, like humans, do not have all the enzymes in the small intestine needed to break down several types of plant fibre. Fibres such as FOS pass through the small intestine undigested and are then fermented by bacteria in the colon.[2]
FOS, galacto-oligosaccharides and inulin are added to several commercial cat and dog foods, and their effects on faecal microbial composition, nutrient digestibility and short-chain fatty acids have been studied, particularly in dogs. In one 2017 study, healthy cats and dogs given a commercial FOS-and-inulin product for 16 days showed shifts in the relative abundance of a few bacterial groups, though these were not enough to separate the overall bacterial communities.[2]
Some lactic-acid bacteria are equipped to use these fibres: the genome of one well-studied Lactobacillus acidophilus strain includes gene clusters for transporting fructooligosaccharides.[3]
On the DIGEST+ label
The DIGEST+ composition lists inulin from chicory root (fructooligosaccharides). It sits alongside the Live Culture Blend (2 billion CFU per tablet) and the Digestive Enzyme Complex (150 mg in total), so the tablet combines a prebiotic fibre with live cultures and enzymes.
Questions people ask
Is inulin the same as FOS?
They are closely related. Both are inulin-type fructans — chains of fructose — and the difference is chain length: FOS (oligofructose) chains are short, roughly 3 to 9 units, while inulin includes much longer chains. The DIGEST+ label describes its chicory root inulin as fructooligosaccharides.
Can dogs digest inulin?
Not with their own enzymes in the small intestine. Fibres such as FOS pass through undigested and are fermented by bacteria in the colon.
Is chicory root inulin a probiotic?
No. Inulin is a prebiotic: a fibre used by gut microbes. Probiotics are live micro-organisms, like the five strains in the DIGEST+ Live Culture Blend.
Work out your exact supply
The calculator on the product page takes your dog’s weight band and how many dogs you have, then shows the daily dose, how long a bottle lasts and a sensible refill rhythm.
Sources
- The effects of chicory inulin-type fructans supplementation on weight management outcomes: systematic review, meta-analysis, and meta-regression of randomized controlled trials — The American Journal of Clinical Nutrition. Checked 2026-10-15.
- Molecular assessment of the fecal microbiota in healthy cats and dogs before and during supplementation with fructo-oligosaccharides (FOS) and inulin using high-throughput 454-pyrosequencing — PeerJ. Checked 2026-10-15.
- Complete genome sequence of the probiotic lactic acid bacterium Lactobacillus acidophilus NCFM — Proceedings of the National Academy of Sciences of the United States of America. Checked 2026-10-15.
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