Hops

Humulus lupulus

Family: Cannabaceae Part used: Strobiles (female flower cones)

Key Compounds

• 2-Methyl-3-buten-2-ol (MBE)
• Humulone (alpha acids)
• Lupulone (beta acids)
• 8-Prenylnaringenin
• Isoxanthohumol
• Xanthohumol
• Myrcene
• Linalool
• Caryophyllene
• Colupulone
• Lupulin
• Rutin

Traditional Use

• Sleep support — dried hops have clinical evidence for improving sleep quality; the mechanism involves 2-methyl-3-buten-2-ol (MBE), a volatile compound that develops as hops oxidize and acts as a GABA-A modulator; fresh hops are less sedative than dried or aged hops because MBE has not yet formed
• Combined with valerian for sleep — the valerian + hops combination has two published RCTs showing it outperforms either herb alone; the combination targets GABA modulation through two different pathways simultaneously
• Bitter digestive tonic — humulones (alpha acids) and lupulones (beta acids) are the primary bittering agents in beer; as bitter compounds, they stimulate digestive secretion; the same mechanism as other digestive bitters but most people encounter it through beer rather than medicine
• Brewing — the primary global use of hops; cultivated since at least the 9th century CE in German Benedictine monasteries; added to beer for bitterness, flavour, aroma, and preservation (iso-alpha acids have antimicrobial activity that extends beer's shelf life)
• Japanese brewing — major Japanese breweries (Sapporo, Kirin, Asahi) import and domestically cultivate hops; the Iwate and Akita regions of Tohoku are established hop cultivation areas; Japanese craft beer culture has expanded hop interest
• Phytoestrogenic activity — 8-prenylnaringenin (8-PN) is derived from isoxanthohumol by gut microbiome conversion; considered the most potent phytoestrogen identified; occupational exposure among female hop harvesters has historically been associated with early menstruation and cycle disruption

Hop pickers used to fall asleep at their work.

This observation — documented in 18th and 19th-century accounts of hop harvesting in England and Germany — was the first indication that handling the plant had sedative properties. Pickers handling fresh hops throughout the day experienced fatigue and drowsiness that seemed beyond the physical demands of the work. The same effect was noticed by brewers working with large quantities of hops.

The pharmacological explanation came much later: 2-methyl-3-buten-2-ol (MBE), a compound that develops as hops dry and oxidize, is a GABA-A modulator. It does not exist in meaningful amounts in fresh hops. The pickers were being affected by what was produced during handling, and by the inhalation of compounds volatilising from large quantities of the plant.

The discovery was reversed. They noticed the effect first. They found the mechanism later.

Meet the plant

A vigorous perennial climbing vine, 6–8 metres per year, with rough lobed leaves and separate male and female plants. Only female plants are cultivated commercially — males are eliminated so the flowers don’t develop seeds. The strobiles are the papery female flower cones: layered, delicate, containing glands of yellow lupulin powder at the base of each bract.

The plant is in Cannabaceae — the cannabis family. The two plants are close botanical relatives and share terpene profiles. This is why some cannabis strains smell like beer, and some hops smell like cannabis.

Beer before medicine

Hops entered European brewing approximately in the 9th century CE. The first documented record of hop cultivation for brewing is from a Benedictine monastery in Bavaria, dated 822 CE. Before hops, beer was flavoured with gruit — a mixture of herbs including bog myrtle, yarrow, and wild rosemary. Hops replaced gruit through the medieval period largely because the iso-alpha acids in hops have antimicrobial activity that preserves beer from bacterial spoilage. A hop-bittered beer keeps longer than a gruit-bittered beer. Preservation chemistry won.

The medicinal use was secondary and delayed. The sedative properties were noticed in hop pickers and brewers; herbalists formalised the application. By the 19th century, European herbalists were using hops for insomnia and nervous conditions. George III of England reportedly slept with a hop-filled pillow.

The oxidation paradox

Fresh hops are minimally sedative. Dried and aged hops are more sedative. This is backwards from how most plant medicines work — compounds usually degrade during storage, not form.

The mechanism: alpha acids (humulones) in fresh hops undergo oxidative degradation during drying and storage to produce 2-methyl-3-buten-2-ol (MBE). MBE is a GABA-A positive allosteric modulator — it potentiates GABA-A receptor activity and produces sedation. It is also volatile: it evaporates at room temperature. This is why the hop pillow — inhaled MBE — is the traditional delivery system, and why it works better with aged dried material than fresh.

The practical implication: hops products for sleep should use dried material that has been stored for a period, not fresh. Fresh hop preparations may not have the sedative activity expected.

The estrogenic surprise

8-Prenylnaringenin (8-PN) is produced from isoxanthohumol in hops by intestinal bacteria after ingestion. 8-PN has been identified as the most potent phytoestrogen measured in any food plant — approximately 10 times the estrogenic activity of genistein from soy.

This explains the documented historical observation that female hop harvesters experienced menstrual cycle irregularities — early menstruation, cycle disruption — associated with occupational hop exposure. High-concentration skin contact and inhalation during harvest delivered significant 8-PN precursor.

At the concentrations in beer — substantially lower than occupational exposure — the estrogenic effect is unlikely to be clinically significant for most people. The compound exists. The context of exposure matters.

What people actually do with it

Capsules or tablets (sleep): Dried hop strobile extract, 100–600 mg before bed. Most effective when combined with valerian: the valerian + hops combination has two RCTs showing it outperforms either herb alone.

Hop pillow: Dried, aged hops stuffed in a small pillow or sachet placed under the pillow. Traditional preparation; the volatile MBE is inhaled. More folk remedy than clinical preparation, but consistent with the mechanism. Refresh the hops annually.

Tincture: 1–2 mL, 30–60 minutes before bed. Fresh plant tincture is less sedating (lower MBE) than dried plant tincture.

Beer: The practical reality is that most people encounter hops through beer. The bitter compounds (humulones) are the bittering agents in virtually all commercial beer. The sedative amounts of MBE in a glass of beer are lower than in a medicinal hops preparation.

Caution: Do not use if you have depression — hops has central nervous system depressant activity that may worsen depressive symptoms.

Could you grow this yourself?

Hops grow well across Japan’s temperate climate. They are already commercially cultivated in Iwate and Akita.

The vine grows 6–8 metres in a season with support — a trellis or fence, or strung wire overhead. It dies back to the ground each winter and regrows vigorously in spring. Harvest in late summer when the cones are papery and fragrant. Dry at low heat (below 40°C) and store in sealed bags — the drying and storage is where the medicinal activity develops.

The plant is attractive in the garden and provides dense summer coverage of a trellis. The aromatic cones in late summer are strongly scented.

Hops (ホップ) in Japan

Japan’s primary relationship with hops is through beer.

Sapporo Beer (founded 1876 in Hokkaido by German-trained brewer Seibei Nakagawa) was among the first Japanese breweries to adopt German brewing techniques including hop-bittered lager. Kirin and Asahi followed. Major Japanese breweries import hops primarily from Germany, the Czech Republic, and the United States.

Domestic hop cultivation in Iwate and Akita (Tohoku) provides premium Japanese-grown hops with distinctive aromatic profiles. The craft beer movement that has grown in Japan since the 1990s has expanded interest in these domestic varieties and in the full range of hop aromatic compounds — not just bitterness.

The medicinal use of hops in Japan is less prominent. Hop extract capsules are available at supplement retailers for sleep support, primarily in combination formulas with valerian and other calming herbs. The connection to beer is strong enough that the plant’s medicinal identity is somewhat obscured by its brewing identity. In Japan, hops is primarily an ingredient in something else.

Things you’re probably wondering

Why do dried hops become more sedative over time? The sedative compound MBE develops from alpha acid oxidation during drying and storage. Fresh hops contain little MBE; dried, aged hops contain more.

What is the hop pillow? A traditional sleep remedy of dried hops stuffed in a sachet under the pillow. Volatile MBE is inhaled during sleep. Works better with aged material.

What is 8-prenylnaringenin? The most potent phytoestrogen identified in any food plant — produced from isoxanthohumol by gut bacteria. Explains historical menstrual disruption in female hop harvesters.

Is hops related to cannabis? Yes — same family (Cannabaceae). They share terpene profiles including myrcene, linalool, and caryophyllene. Hops does not contain cannabinoids.

Botanical details

The full compound list

See Also

• Valerian — combined in two RCTs for superior sleep outcomes; standard valerian + hops combination
• Lemon Balm — calming herb often combined with hops and valerian in sleep formulas
• Passionflower — another GABA-modulating nervine for sleep and anxiety

References

• Schiller, H. et al. (2006). Sedating effects of Humulus lupulus L. components. Phytomedicine, 13(8), 535–541.
• Franco, L. et al. (2012). The sedative effects of hops (Humulus lupulus) combined with valerian. Acta Physiologica Hungarica, 99(2), 133–139.
• Milligan, S.R. et al. (1999). Identification of a potent phytoestrogen in hops (Humulus lupulus L.). Journal of Clinical Endocrinology and Metabolism, 84(6), 2249–2252.
• Stevens, J.F. & Page, J.E. (2004). Xanthohumol and related prenylflavonoids from hops and beer. Phytochemistry, 65(10), 1317–1330.