Glossary

Adaptogen — a marketing category, not a pharmacological one. No agreed definition, no receptor, no regulatory standard. Individual plants in the category have small trials.

Astringent — a substance that precipitates proteins on a surface, tightening tissue. Tannins do this. Useful for a weeping surface, a mild burn or a graze, and a nuisance in a tea that tastes harsh.

Bioavailability — the fraction of a substance that reaches the bloodstream unchanged. Curcumin's is the reason a curry is not a clinical trial.

Chemotype — a chemical variant of a species, usually distinguished by which essential-oil constituents it produces. Thymus vulgaris has thymol and linalool chemotypes; they are the same species and different medicines.

Decoction — a sustained simmer of hard plant material. Root, bark, seed.

Demulcent — a substance that forms a soothing film, usually a mucilage. Marshmallow, slippery elm, plantain. Destroyed by heat, which is why a demulcent is a cold infusion.

Essential oil — the volatile, steam-distilled fraction of a plant. Concentrated, and a solvent in its own right: an essential oil is not a diluted plant.

Extract, standardised — a preparation adjusted so that a marker compound is present at a defined amount. Trials use these; a home preparation is different.

Glycerite — a glycerol-based extract, alcohol-free. Carries mid-polar compounds and not resins.

Hydrosol — the water that co-distils with an essential oil, containing dissolved volatiles at around 0.1%. Not a substitute for the oil and it spoils.

Infusion — a steep of leaf or flower in hot water. A tea.

Menstruum — the solvent in an extraction. Its ethanol percentage is the most important variable in a tincture.

Mucilage — a polysaccharide that swells in water and forms a gel. Heat degrades it.

Nocebo — the counterpart of placebo: harm produced by the expectation of harm. A real mechanism and a common source of invented side effects.

Oxymel — honey and vinegar. Both are preservatives, by different mechanisms.

Phytate (phytic acid) — the storage form of phosphorus in seeds, which chelates iron, zinc, calcium and magnesium. Fermentation degrades it. This is why fermentation raises mineral absorption.

Phytoestrogen — a plant compound with weak oestrogenic activity. Soy isoflavones are the common example. The term is used loosely in marketing; the clinical effect size is small.

Placebo — a real response to expectation and ritual, mediated by measurable neurochemistry. Not the same as nothing, and not evidence that a preparation works.

Poultice — crushed plant material or a soaked cloth applied to skin.

Regression to the mean — the statistical tendency of an extreme measurement to be followed by one closer to average. Why starting a remedy at the worst point always seems to help.

Salve — an infused oil thickened with beeswax. A semi-solid vehicle. Not sterile.

Sensitisation — an immune reaction acquired by exposure. Neat essential oils cause it, and it is generally permanent. An oxidised oil is more allergenic than a fresh one.

Synergy — a claim that components act better together. Frequently asserted for plant extracts, rarely demonstrated, and often a way to avoid testing the component alone.

Tincture — an ethanol-water extract, defined by its plant-to-solvent ratio and its ethanol percentage. Above roughly 20% ethanol it is self-preserving.

U-curve — a dose-response relationship in which effect reverses direction above a point. Potassium and blood pressure is the worked example.

Volatile — evaporating at room temperature. The monoterpenes that make an aromatic tea work are volatile, which is why the vessel is covered.

Water activity — the availability of water for microbial growth, lowered by salt and sugar. The mechanism behind brine fermentation and honey preservation.