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Hops (Humulus lupulus L.)


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Hops (Humulus lupulus L.)

Background

A hop is a member of the Cannabacea family, traditionally used for relaxation, sedation, and to treat insomnia. A number of methodologically weak human trials have investigated hops in combination with valerian (Valeriana officinalis) for the treatment of sleep disturbances, and several animal studies have examined the sedative properties of hops monotherapy. However, the results of these studies are equivocal, and there is currently insufficient evidence to recommend hops alone or in combination for any medical condition.

Hops are also sometimes found in combination products with passionflower (Passiflora incanata) , skullcap (potentially hepatotoxic), or with a high percentage of alcohol (up to 70% grain alcohol), confounding the association between the herb and possible sedative or hypnotic effects.

Hops contain phytoestrogens that may possess estrogen receptor agonist or antagonist properties, with unclear effects on hormone-sensitive conditions, such as breast, uterine, cervical, or prostate cancer, or endometriosis.

Synonyms

Common hops, European hops, hop, hop strobile, Hopfen (German), houblon (French), humulus, lupulin, lupulus, Lupuli strobulus, Ze 91019.

Selected combination products : Avena Sativa Compound in Species Sedative Tea, HR 129 Serene, Hova®-Filmtabletten, HR 133 Stress, Melatonin with Vitamin B6, Seda-Kneipp®, Snuz Plus, Stress Aid, Valverde®, Zemaphyte®.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidenceGrade*Insomnia/sleep quality
Animal studies report that hops may have sedative and sleep-enhancing (hypnotic) effects. However, little human research has evaluated the effects of hops on sleep quality. Some studies combine hops with valerian ( Valeriana officinalis ), and the effects of hops cannot be separated from the possible benefits of valerian. Further study is needed in this area before a recommendation can be made.

C

Sedation
Hops have been used traditionally as a sedative, for relaxation and reduction of anxiety. Although some animal studies suggest possible sedative properties, there is limited human research in this area. Better studies are needed before a firm conclusion can be drawn.

C

* Key to grades
A:
Strong scientific evidence for this use;
B:
Good scientific evidence for this use;
C:
Unclear scientific evidence for this use;
D:
Fair scientific evidence against this use (it may not work);
F:
Strong scientific evidence against this use (it likely does not work).

Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Antidepressant, antibacterial, anti-inflammatory, antispasmodic, anxiety, aphrodisiac, appetite stimulant, breast cancer, cancer (general), Crohn's disease, dermatitis, diabetes, diarrhea caused by infection, digestion, Epstein-Barr virus, estrogenic effects, indigestion, irritable bowel syndrome, kidney disorders, leprosy, lung disease (from inhalation of silica dust or asbestos), anxiety during menopause, mood disturbances, muscle and joint disorders, muscle spasm, pain, parasites, restlessness, skin ulcers (hops used on the skin), tuberculosis.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Standardization

Standardization involves measuring the amount of certain chemicals in products to try to make different preparations similar to each other. It is not always known if the chemicals being measured are the "active" ingredients. Some hops extracts are standardized to 5.2% bitter acids and/or to 4% flavonoids per dose.

Adults (18 years and older)

Oral (by mouth) : For insomnia or sleep disturbances, research has used 300 to 400 milligrams of hops extract combined with 240 to 300 milligrams of valerian extract, taken before bed. Traditionally, doses of 0.5 to 1.0 gram of dried hops extract or 0.5 to 1.0 milliliters of liquid hops extract (1:1 in 45% alcohol) have been taken up to three times daily, although using hops alone has not been well studied.

Intravenous/intramuscular : Not recommended. In animal studies, large injected doses have resulted in a narcotic effect, followed by death. Long-term therapy has resulted in weight loss and death.

Children (younger than 18 years)

Oral (by mouth) : Hops extract is traditionally considered to be one of the milder sedative herbs, and to be safe for children. However, there is limited research in this area, and safety has not been clearly established. Some natural medicine experts suggest adjusting the dose according to body weight (multiply the usual adult dose by the child's weight in pounds, then divide by 150).

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

Rash (contact dermatitis) and difficulty breathing have been reported mainly in hops harvesters. Allergy to hops pollen has also been reported. Hops allergy has been reported in a patient with previous severe allergic reactions to peanut, chestnut and banana. Therefore people allergic to any of these agents should avoid hops.

Side Effects and Warnings

There are no reported serious side effects associated with hops in the available scientific literature. Hops may cause mild central nervous system (CNS) depression (drowsiness, slowed breathing and thinking), especially when taken with drugs or herbs/supplements that also cause CNS depression. Caution is advised while driving or operating machinery.

Animal studies report that eating hops in large quantities may cause seizure, hyperthermia, restlessness, vomiting, stomach pain, and increased stomach acid. Laboratory research shows that estrogen-like substances in hops may have stimulatory or inhibitory effects on estrogen-sensitive parts of the body, and it is unclear what effects may occur in hormone-sensitive conditions such as cancer (breast, uterine, cervical, prostate), or endometriosis.

Based on preliminary animal studies, hops may lower blood sugar levels in normal individuals, but may actually increase blood sugar in those with diabetes. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary.

Long-term breathing problems have been reported in brewery workers exposed to hops dust.

Pregnancy and Breastfeeding

Hops is not recommended during pregnancy or lactation due to possible hormonal and sedative effects. Limited research is available in these areas. Many tinctures contain high levels of alcohol, and should be avoided during pregnancy.

References

1. Collie ME, Higgins JC. Hope for hops? Arch Intern Med. 2002 Feb 11;162(3):364-5. Comment on: Arch Intern Med. 2001 Aug 13-27;161 (15) :1844-8.

2. Duncan KL, Hare WR, Buck WB. Malignant hyperthermia-like reaction secondary to ingestion of hops in five dogs. J Am Vet Med Assoc 1997;210(1):51-54.

3. Estrada JL, Gozalo F, Cecchini C, Casquete E. Contact urticaria from hops (Humulus lupulus) in a patient with previous urticaria-angioedema from peanut, chestnut and banana. Contact Dermatitis. 2002 Feb;46(2):127.

4. Gerhard U, Linnenbrink N, Georghiadou C, et al. [Vigilance-decreasing effects of 2 plant-derived sedatives]. Schweiz Rundsch Med Prax 1996;85(15):473-481.

5. Gerhauser C, Alt A, Heiss E, Gamal-Eldeen A, Klimo K, Knauft J, Neumann I, Scherf HR, Frank N, Bartsch H, Becker H. Cancer chemopreventive activity of Xanthohumol, a natural product derived from hop. Mol Cancer Ther. 2002 Sep;1(11):959-69.

6. Godnic-Cvar J, Zuskin E, Mustajbegovic J, et al. Respiratory and immunological findings in brewery workers. Am J Ind Med 1999;35(1):68-75.

7. Hänsel R, Wohlfart R, Schmidt H. The sedative-hypnotic principle of hops. 3. Communication: contents of 2-methyl-3-butene-2-ol in hops and hop preparations. Planta Med 1982;45:224-228.

8. Henderson MC, Miranda CL, Stevens JF, et al. In vitro inhibition of human P450 enzymes by prenylated flavonoids from hops, Humulus lupulus. Xenobiotica 2000;30(3):235-251.

9. Hengel MJ, Shibamoto T. Gas chromatographic-mass spectrometric method for the analysis of dimethomorph fungicide in dried hops. J Agric Food Chem. 2003 Mar 12;51(6):1760.

10. Kapadia GJ, Azuine MA, Tokuda H, Hang E, Mukainaka T, Nishino H, Sridhar R. Inhibitory effect of herbal remedies on 12-o-tetradecanoylphorbol-13-acetate-promoted Epstein--Barr virus early antigen activation. Pharmacol Res. 2002 Mar;45(3):213-220.

11. Leathwood PD, Chauffard F, Heck E, et al. Aqueous extract of valerian root (Valeriana officinalis L.) improves sleep quality in man. Pharmacol Biochem Behav 1982;17(1):65-71.

12. Milligan S, Kalita J, Pocock V, Heyerick A, De Cooman L, Rong H, De Keukeleire Oestrogenic activity of the hop phyto-oestrogen, 8-prenylnaringenin. Reproduction. 2002 Feb;123(2):235-42.

13. Milligan SR, Kalita JC, Heyerick A, et al. Identification of a potent phytoestrogen in hops (Humulus lupulus L.) and beer. J Clin Endocrinol Metab 1999;84(6):2249-2252.

14. Milligan SR, Kalita JC, Pocock V, et al. The endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids. J Clin Endocrinol Metab 2000;85(12):4912-4915.

15. Muller CE, Schumacher B, Brattstrom A, Abourashed EA, Koetter U. Interactions of valerian extracts and a fixed valerian-hop extract combination with adenosine receptors. Life Sci. 2002 Sep 6;71(16):1939-49.

16. Muller-Limmroth W, Ehrenstein W. [Experimental studies of the effects of Seda-Kneipp on the sleep of sleep disturbed subjects; implications for the treatment of different sleep disturbances]. Med Klin 1977;72(25):1119-1125.

17. Newmark FM. Hops allergy and terpene sensitivity: an occupational disease. Ann Allergy 1978;41(5):311-312.

18. O'Donovan W. Hops dermatitis. Lancet 1924;2:597.

19. Pradalier A, Campinos C, Trinh C. Systemic urticaria induced by hops [Article in French]. Allerg Immunol (Paris). 2002 Nov;34(9):330-2.

20. Schaefer O, Humpel M, Fritzemeier KH, Bohlmann R, Schleuning WD. 8-Prenyl naringenin is a potent ERalpha selective phytoestrogen present in hops and beer. J Steroid Biochem Mol Biol. 2003 Feb;84(2-3):359-60.

21. Schmitz M, Jackel M. [Comparative study for assessing quality of life of patients with exogenous sleep disorders (temporary sleep onset and sleep interruption disorders) treated with a hops-valarian preparation and a benzodiazepine drug]. Wien Med Wochenschr 1998;148(13):291-298.

22. Spiewak R, Dutkiewicz J. Occupational airborne and hand dermatitis to hop (Humulus lupulus) with non-occupational relapses. Ann Agric Environ Med. 2002;9(2):249-52.

23. Vonderheid-Guth B, Todorova A, Brattstrom A, et al. Pharmacodynamic effects of valerian and hops extract combination (Ze 91019) on the quantitative-topographical EEG in healthy volunteers. Eur J Med Res 2000;5(4):139-144.

24. Wohlfart R, Hansel R, Schmidt H. [The sedative-hypnotic action of hops. 4. Communication: pharmacology of the hop substance 2-methyl-3-buten-2-ol]. Planta Med 1983;48(2):120-123.

25. Zenisek A, Bednar IJ. Contribution of the identification of the estrogen activity of hops. Am Perfumer Arom 1960;75:61.

January 01, 2004

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