Dandruff

About half of all adults deal with dandruff at some point. It’s a mild form of seborrheic dermatitis limited to the scalp — white or yellowish flakes, sometimes accompanied by itching, caused by the yeast Malassezia disrupting normal scalp skin turnover.

Most anti-dandruff shampoos work on a single front: zinc pyrithione or ketoconazole kills the yeast, or selenium sulfide slows cell turnover. Peat mirrors the strategy used by the most effective commercial products — combining antifungal action with flake removal — but through natural compounds.

Why peat may help

Targeting the yeast. Dandruff is fundamentally a fungal problem. Malassezia yeast lives on everyone’s scalp, but in dandruff sufferers it overgrows and irritates the skin. Humic acids have demonstrated antifungal activity relevant to Malassezia (Wollina 2009). This is the same target that ketoconazole shampoos attack, but through a different chemical mechanism.

Removing flakes. The keratolytic action of humic substances breaks down the protein bonds holding dead skin cells together — loosening and removing the visible flakes. This is equivalent to what salicylic acid does in medicated shampoos.

Restoring scalp pH. Many conventional shampoos are alkaline, which disrupts the scalp’s acid mantle and creates a more hospitable environment for yeast overgrowth. Peat’s natural acidity (pH 3.5–5.5) supports the acid mantle rather than stripping it — addressing a root cause that many shampoos actually worsen.

Stopping the itch. The anti-pruritic properties of peat provide relief from the itching that accompanies dandruff, helping break the scratch-irritation cycle.

What the evidence says

One clinical study provides direct support: a 12-week trial using peat shampoo found reduced scalp flaking (squames), decreased sebum, and improved scalp moisture. This addresses all the measurable signs of dandruff — flakes, oiliness, and scalp health — though the study wasn’t designed as a dandruff trial specifically.

There’s also an interesting historical connection: tar-based anti-dandruff shampoos share chemical ancestry with peat. Coal tar and peat-derived compounds come from the same family of organic matter decomposition products. The active compounds in tar shampoos — polycyclic aromatics and phenolics — are also present in peat, though in different proportions. Tar shampoos have decades of proven efficacy; peat may work through similar pathways.

What’s missing: No RCTs have tested peat specifically for dandruff. The evidence is a combination of one scalp health study, mechanism-based reasoning from known antifungal and keratolytic properties, and the historical parallel with tar-based treatments.