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Hops Flower


Ingredient Type: Botanical, Extract, Herb

Also Known As: Asperge Sauvage, Common Hops, Coleuvrée, Coleuvrée Septentrionale, European Hops, Hops Hop Strobile, Hopfenzapfen, Houblon, Humulus lupulus, Lupuli Strobulus, Lupulin, Lúpulo, Pi Jiu Hua, Salsepareille Indigéne, Vigne du Nord

Hops is known as the flower of the hop plant, Humulus lupulus, which is a member of the Cannabaceae plant family (21). It is native to the Northern Hemisphere, 75% of its annual harvest is found in Washington, 15% from Oregon and 10% Idaho. The hops plant grows for about 3 months between May and July in temperate climate zones. The flower blossoms once the plant reaches a specific height as well as based on the length of day (not too long and not too short), hence why cultivation is mainly present in North America. In Europe however, hops cultivation is limited to Germany, Great Britain, Poland and Czech Republic. Similarly, in Asia, cultivation is limited to specific areas of China and to a limited extent, Japan (12).

The chemical composition of hops includes alpha and beta acids, essential oils, flavonoids, as well as cellulose, water and various plant proteins (19). The alpha acids are probably the most important chemical constituent of hops which is responsible for beers’ bitter tase, while the beta acids and essential oils are responsible for the aroma found in beer (5, 17). A potent phytoestrogen, xanthohumol is the principal flavonoid present in hops (20).

Aside from beer, hops was commonly found or used in herbal tea and soft drinks as well. Between the 1800 – 1900’s, hops was found to be used for everything from hair growth to inflammation and purging bile. It wasn’t until the mid to late 1900’s that the medicinal uses were more well understood and researched.


According to records, the first known use of hops in beer was in the 9th century through Hildegard of Bingen (11). While it is widely known that hops is used primarily as a bittering, flavoring and antimicrobial agent in the beer making process, its similar qualities are what make it an ideal herb for medicinal purposes as well. Around the 1500’s hops was note to be used as a digestive aid by Paracelsus, a diuretic by Matthioulus, and a blood, liver and spleen cleanser by Lonicerus (15). Towards the end of the 1800s the use of hops became more mainstream in the United States as a treatment for insomnia and as a digestive aid. Around the 1900s, eclectic or alternative physicians used hops as a hypnotic to help with sleeplessness due to worry, anxiety and nerve weakness.


Hops and Sleep

One of the most well-known effects of hops is its ability to induce sleep. This is attributed to a yellowish, resinous substance produced from the female flower, also known as lupulin. Lupulin is known to exhibit an effect that promotes sleepiness and appeases the excited nervous system, all without causing constipation (6). According to research, this sedative effect is due primarily due to the bitter resins, or alpha acids present in the hops flower. The mechanism behind hops sedative effect is that the resin increases the activity of the neurotransmitter y-aminobutyric acid (GABA), therefore inhibiting the central nervous system.

This particular study was conducted in order to assess the sedative effect exhibited by hops on the activity and rest rhythm in an animal model. The animal used in this study was the common quail which has a similar sleep-wake rhythm to humans. The doses administered to the treatment group was close to the content of non-alcoholic beer (1, 2, and 11mg extract of hops) in the form of one capsule per day for the duration of one week. The control group received a capsule with a methylcellulose excipient. Data revealed that the 2mg dosage was more effective in reducing nocturnal activity and preserving the circadian activity/rest rhythm than that other two dosages (1mg & 11mg). The researchers concluded that administration of non-alcoholic beer would be recommended as an aid to nocturnal sleep due to the sedative effects associated with the 2mg hop extract concentration (8).

A similar study was conducted in order to analyze the sedative effect of hops as a component of non-alcoholic beer on the sleep/wake cycle of individuals from a work-stressed population. The test group in this study consisted of 17 nurses who rotated on the night shift. In response, the overnight sleep and chronobiological parameters were assessed. Study participants ingested a non-alcoholic beer containing hops (333ml by volume) with dinner for a duration of 14 days. Data was observed and the results revealed an improvement in sleep quality in the treatment group vs the control group. Additionally, in the treatment group, their anxiety score was markedly decreased as indexed by the State-Trait Anxiety Inventory. It was concluded that moderate non-alcoholic consumption favors night-time rest, due primarily to its hops component (9).

With beer being the only beverage that contains hops on a retail level, this study aimed to assess its sedative effect by determining whether consumption amongst a stressed, sleep-deprived population improves subjective sleep quality. The Pittsburgh Sleep Quality Index was utilized as a measuring tool to determine the effectiveness of consuming, for this study, non-alcoholic beer. The sample group studied consisted of 30 university students over a period of 3 weeks with the first 7 days used as a control period and the following 14 days as the test period. The results revealed that students consuming one non-alcoholic beer during dinner had a decreased sleep latency period when compared to the control period. Overall, the global score of sleep quality improved significantly as well. While it is not suggested to consume regular beer on a daily basis, consumption of non-alcoholic beer or a hops supplement at dinner time may help to improve one’s quality of sleep (10).

Hops and Digestion

Traditionally, one of the common uses of hops was to alleviate gastrointestinal discomfort and support digestive processes through the increase of gastric secretions. This study investigated the pharmacological effects of hops on gastric juice secretion and acidity using the animal model. This study compared the intraoral vs intragastric administration of hops. It was found that the intraoral administration resulted in an increase in gastric juice volume while not increasing the acidity off the gastrointestinal environment. On the other hand, introduction of hops intragastrically did not encourage any increase in gastric juice secretion. From a physiological standpoint, the increase in gastric juice secretion by intraoral administration of hops can be mediated by the cholinergic nervous system (13).

This study was conducted to assess whether there was a correlation between the consumption of hops and an increase in the beneficial bacteria within the gastrointestinal tract through the use of in vitro batch culture systems. Over a period of 24-hours, fermentation occurred utilizing mixed human inoculum. The microbiotic metabolism was measured though the volume of organic acid production and observed alterations to the microbial community. The researchers recognized that levels of butyrate decreased at elevated concentrations of hops while also inhibiting the presence of bifidobacterium, which is considered a beneficial organism within the gastrointestinal environment. Interestingly, in the presence of hops, potentially pathogenic Enterobacteriaceae and potentially beneficial Akkermansia were noted to increase in a dose-dependent manner. While the results were rather in conclusive as to whether there was more of a benefit vs drawback with regard to the effects of hops on the digestive microbiota, it was recognized that there is a significant shift in flora when in the presence of hops. More research is necessary to understand the mechanisms behind the microbiotic floral changes within the human gastrointestinal tract (3).

Antimicrobial Properties of Hops

Amongst the medicinal effects of hops is said to be its antimicrobial activity. This study was intended to assess the effects of hops on hyper ammonia producing-bacteria (HAB), which is known to catabolize proteins and their constituents in bovine rumen. Based on the results, it was observed that the ammonia produced by mixed bacteria of the rumen was inhibited in the presence of dried hops or hops extract. The addition of hops to energized cellular suspensions also was observed to rapidly decrease intracellular pH while concurrently losing intracellular potassium. The results indicated that the three HAB species were indeed sensitive to the antimicrobial compounds in hops, potentially yielding similar effects in the rumen (7).

Bacteroides fragilis and Clostridium perfringens are examples of anaerobic bacteria that are commonly found in the human gastrointestinal tract. Others such as Clostridium difficile are also present in very limited numbers; however, when found in high volumes has been linked as a causative agent of nosocomial infections associated with antibiotic resistant diarrhea. Attempting to treat C. difficile has been rather challenging, making it vital to search for alternative compounds with antimicrobial properties (4).

To further support the antimicrobial activity of hops, this study was conducted in order assess the biological activity of hops essential oil (EO) against Sitophilus granarius. From the standpoint of pest control, there is little to no research on the effectiveness of hops as an alternative to pest control. According to the reports, adult toxicity was noted within 24 hours following treatment of the hops essential oil which consisted mainly of α – humulene, Ɓ – myrcene and Ɓ – caryophyllene. Additionally, the EO terpenes were recognized by insect antennae in which the adults reacted in a repelled manner. Based on the researchers’ observations, the hops EO was suitable for the use of controlling this specific pest. Further research is necessary to better understand the mechanisms of action exhibited by the hops essential oil constituents (18).

Hops, Anxiety and Depression

Similarly, to how hops has a sedative-like effect to support sleep, this effect tends to support cognitive functions as well, specifically anxiety, depression and stress. One team of researchers sought out to study in more detail the effects of hops extract in a dry form on young adults with self-reported anxiety, depression and elevated stress levels. The design of the study incorporated 2, 4-week intervention periods in which a total of 36 participants were randomly assigned to either a placebo or treatment group receiving Melcalin hops. The two trial periods were separated by a 2-week washout period. The data was measured through anthropometric measurements, DASS-21 assessments, along with morning cortisol plasma levels at start and conclusion each of the 4-week treatment periods. While there was no significant change in body weight, composition or circulating morning cortisol, the data did suggest a significant decrease in anxiety, depression and stress upon daily supplementation with the dry hops extract. The researchers agreed that there is indication for the use of hops for certain mood disorders and restlessness as approved currently by the German Commission (14).

This study was conducted in order to further investigate the central nervous system activity of Humulus lupulus CO2 extract and its fractionated alpha-acids. Upon administration to the subjects, it was observed that both tested substances were able to prolong sleep time in a dose-dependent manner. It was also noted that neither of the substances affected locomotor activity or exerted an anxiolytic effect on the subjects. The researchers gathered that the Humulus lupulus CO2 extract exhibited a pentobarbital sleep-enhancing effect without affecting the motor-skills/motor-behavior. Additionally, it was also noted to exhibit an antidepressant activity. Both the Humulus lupulus CO2 extract and it fractionated alpha-acids exhibited the same properties which led the researchers to conclude that the alpha-acids are majorly responsible for the enhanced effects noted in this study (22).

Due to there being limited scientific studies on the effect of hops on the nervous system, various experiments have been conducted to assess the mechanisms behind the activity. The following experiments in this study utilized a fixed valerian-hops extract (Ze91019) as a sleep aid. It is suggested that both valerian and hops act/interact with the GABA adenosine and/or melatonin systems in the brain. While most of the observed effects of hops as a sleep and anxiety aid are based on traditional use, more research is being conducted to reinforce its suggested activity. Ze91019 was tested on 14 subtypes of central nervous system receptors (dopamine, melatonin, neuropeptide ƴ, MCH and serotonin). It was recognized that there were binding affinities with melatonin and serotonin receptor subtypes which helps reinforce the effects of hops and valerian on anxiety, sleep and stress (1).


The use of hops and hops oils is considered safe, especially when consumed in dosages commonly found in foods and beverages such as beer. Consumption of hops as a supplement is considered possibly safe when taken orally under the supervision of a medical professional. While there is limited scientific information related to the safety and toxicity of hops consumption, the adverse reactions are known to be few.

Side Effects:

While side effects are known to be limited, there are specific situations in which the consumption and/or supplementation of hops can be considered hazardous to one’s health (16).

  • Pregnancy & Breastfeeding: Given that there is extremely limited information on the safety of taking hops, it is suggested to avoid taking hops while pregnant & breastfeeding. It is recommended that you consult your medical professional prior to taking this or any other supplement under these circumstances.
  • Depression: It is suggested that those suffering with depression not consume hops as it can exacerbate or make worse the state of depression.
  • Hormone Sensitive Cancer & Related Conditions: Hops is known to exhibit low estrogenic activity. Those who are either sensitive to hormones of have a condition such as cancer or endometriosis, should avoid hops all together.
  • Surgery: For those who are scheduled to have surgery, it is recommended that you stop taking hops 2 weeks prior to surgery as the nervous system effects

Those farming and handling high volumes of hops extract and the dried plant occasionally experienced allergic reactions (2).


It is strongly advised to consult with your healthcare professional prior to consuming hops if you intend to supplement hops with any of the following (16):

  • Alcohol: It is recommended that you take precautions when consuming hops if you intend to drink or are currently drinking alcohol as alcohol along can cause sleepiness. Supplementing with hops can exacerbate the effect of sleepiness and drowsiness.
  • Estrogen: Hops is known to have a low estrogenic effect and when taken with someone supplementing with estrogen pills or birth control may experience increased side-effects associated with higher-than-normal levels of estrogen. Some of the estrogen pills include conjugated equine estrogens, ethinyl estradiol, estradiol, etc. (16).
  • Medications Changed by the Liver (CYP1A1, CYP1A2, CYP1B1, CYP3A4: Medications are typically broken down or modified through the actions of the liver. Due to the activity of hops, it may decrease how quickly the liver breaks down and/or metabolizes the medications, therefore potentially increasing the effects and side effects of those medications. Some of the medications include diltiazem, nicardipine, verapamil, etoposide, paclitaxel, vinblastine, vincristine, vindesine, ketoconazole, intraconazole, alfenta, propulsid, sublimaze, xylocaine, cozaar, allegra and versed, amongst others (16).
  • CNS Depressants: Similar to the effects of alcohol, CNS depressants or sedative medications combined with the supplementation of hops may exacerbate the effects causing excess sleepiness and drowsiness. Some of the medications include clonazepam, lorazepam, phenobarbital and zolpidem (16).


  1. Abourashed, E A et al. “In Vitro Binding Experiments with a Valerian, Hops and their Fixed Combination Extract to (Ze91019) to Selected Central Nervous System Receptors.” Phytomedicine: International Journal of Phytotherapy and Phytopharmacology 11,7-8 (2004): 633-8. doi:
  2. American Herbal Products Association’s Botanical Safety Handbook. 2nd, Boca Raton, FL: CRC Press, LLC, 2013. McGuffin, Gardner, eds.
  3. Blatchford, P. A., et al. “Dose-Dependent Alterations to In Vitro Human Microbiota Composition and Butyrate Inhibition by a Supercritical Carbon Dioxide Hops Extract.” Biomolecules 9, 9 (2019): 390.
  4. Cermak, Pavel et al. “Strong antimicrobial activity of xanthohumol and other derivatives from hops (Humulus lupulus L.) on gut anaerobic bacteria.” APMIS : acta pathologica, microbiologica, et immunologica Scandinavica 125,11 (2017): 1033-1038. doi:
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  13. Kurasawa T, Chikaraishi Y, Naito A, Toyoda Y, Notsu Y. Effect of humulus lupulus on gastric secretion in a rat pylorus-ligated model. Biol Pharm Bull. 2005;28(2):353-357. doi:
  14. Kyrou, loannis et al. “Effects of a hops (Humulus lupulus L.) dry extract supplement on self-reported depression, anxiety and stress levels in apparently healthy young adults: a randomized, placebo-controlled, double-blind, crossover pilot study.” Hormones (Athens, Greece) 16.2 (2017): 171-180. doi:
  15. Madaus G. Lehrbuch der Biologischen Heilmittel. Leipzig: Georg Thieme Verlag; 1938.
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  18. Paventi, Gianluca et al. “Biological Activity of Humulus Lupulus (L.) Essential Oil and Its Main Components Against Sitophilus granarius(L.).” Biomolecules 10,8 1108. 25 Jul. 2020, doi:
  19. Schönberger C, Kostelecky T (16 May 2012). “125th Anniversary Review: The Role of Hops in Brewing”Journal of the Institute of Brewing117(3): 259–267. doi: 2011.tb00471.x
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  21. “University of Minnesota Libraries: The Transfer of Knowledge. Hops-Humulus lupulus”. 13 May 2008. Retrieved 3 August 2022.
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