Hair

Inulin — a prebiotic that feeds the scalp microbiome

8 September 2026

Inulin is a polysaccharide — a chain of fructose units ending in glucose. It occurs naturally in chicory root, Jerusalem artichoke, garlic and onion. In food it is a soluble fibre. In a cosmetic it does two jobs at once.

First function: prebiotic

Humans do not digest inulin — we lack the enzymes that break the bonds between fructose units. Bacteria do. And not all of them: selectively genera such as Lactobacillus and Bifidobacterium, regarded as beneficial.

That is the definition of a prebiotic: a food source only selected microorganisms can use. Nothing is killed. The balance shifts by giving one side a nutritional advantage.

On the scalp it works the same way. The scalp microbiome is mainly Cutibacterium and Staphylococcus bacteria and Malassezia yeast. Flaking and chronic itch correlate with a shift in those proportions, not with the mere presence of any one organism — Malassezia lives on every healthy scalp.

A prebiotic approach differs from classic anti-dandruff care. A zinc pyrithione or ketoconazole shampoo suppresses Malassezia. An inulin shampoo supports what should grow. The first approach fits flare-ups better; the second fits everyday balance, including after a course of treatment. A cosmetic does not treat dandruff or seborrhoeic dermatitis. It can support microbiome balance.

Pre-, pro-, post- — sorting the words

• —Prebiotic — food for beneficial microorganisms (inulin, alpha-glucan, fructooligosaccharides)
• —Probiotic — live microorganisms. Rare in cosmetics, because keeping live cultures in a preserved formula is difficult
• —Postbiotic — bacterial metabolites: ferment, lysate, filtrate. For example Lactobacillus Ferment

When a formula holds both a prebiotic and a postbiotic — inulin next to Lactobacillus Ferment in our conditioner — that is a synbiotic set-up: metabolites act immediately, and the food source supports flora over time.

Second function: humectant and film

Inulin binds water through its many hydroxyl groups and forms a thin, breathable film on the surface. Practical effects:

• —less friction between hairs, easier detangling
• —less water loss from the fibre
• —smoothness without weight — unlike silicones, it does not build up wash after wash
• —it works well with cationic conditioner ingredients, helping them spread

That is why it belongs in both shampoo (where little remains, but it reaches the scalp) and conditioner (where it has time and conditions to work on the fibre).

What inulin does not do

It does not treat dandruff. It does not replace treatment of seborrhoeic dermatitis. It does not work overnight — microbiome shifts take weeks of regular use. It is a supporting ingredient, not an intervention, and it is more honest to say so.