Cannabaceae
Humulus lupulus
Hops
- Part used
- flower
- Native range
- Europe, western Asia and North America
- Morphology
- A vigorous perennial climber twining clockwise to eight metres, with rough lobed leaves. The part used is the papery cone-like female flower, whose bracts carry glands of bitter yellow resin.
What is in it
Evidence
Small trials, usually in combination with valerian, report modest improvement in sleep. Alone, the evidence is thin. The oestrogenic activity is the better-characterised pharmacology.
Safety
Contains 8-prenylnaringenin, one of the most potent phytoestrogens known. Hop-pickers historically experienced menstrual disturbance from handling the plant, which is a real occupational observation. Caution in hormone-sensitive conditions. Sedative at higher doses. Notably toxic to dogs, causing malignant hyperthermia — a genuine risk around home brewing.
Interactions: Additive sedation with CNS depressants; Oestrogenic activity; caution with hormone therapy and in hormone-sensitive cancer
Regulatory: Permitted as a food and as a listed ingredient.
How the traditions classify it
Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.
Historical use
Used in brewing from around the ninth century, principally as a preservative — hop resins inhibit the bacteria that spoil beer, which is why hopped beer travelled and unhopped ale did not. Medicinally used for sleep, and hop pillows were a standard remedy for insomnia.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Hops are in beer for microbiology rather than for flavour. Hop resins inhibit Gram-positive spoilage bacteria, which is why hopped beer keeps and unhopped ale does not — and why India Pale Ale was hopped heavily enough to survive a voyage to India. The bitterness was a side effect that became the point.
Its medicinal reputation rests on an occupational observation that turned out to be pharmacology. Hop-pickers, historically mostly women, reported menstrual disturbance during the harvest, and that folk observation was eventually explained by 8-prenylnaringenin — among the most potent phytoestrogens known.
The sedative reputation has a comparable origin: pickers were noted to fall asleep in the fields. Whether the hop pillow does anything is much less clear than the oestrogen.
Nomenclature verified against GBIF backbone taxonomy.