Humulus lupulus (hops) are best known for their role in beer, however, the flowers of the plant are also being investigated for their health benefits — in particular, those which affect women.
In 1999, a potent phytoestrogen, 8-prenylnaringenin, whose activity was stronger than that of other phytoestrogens, was found in Humulus lupulus.1
Phytoestrogens found in plants can have estrogenic or antiestrogenic effects due to their ability to occupy estrogen receptor sites, thereby blocking estrogen made in the body. This may enable some plant compounds to provide some of the benefits of estrogen while blocking some of their adverse effects.
While 8-prenylnaringenin has strong estrogenic activity, the authors of one study point out that the concentration needed to stimulate the vaginal epithelium of ovariectomized mice (female rodents whose ovaries have been removed) was about 500 times greater than that of any beer, which helps to alleviate concerns regarding potential adverse effects.2
Indeed, another study that utilized ovariectomized rodents found lower levels of serum estrogen after supplementation with hops, in addition to a reduction in insulin, serum free fatty acids, and malondialdehyde, a marker of oxidative stress.3 Hops have also been found to contain resveratrol, an antioxidant compound that has elicited some of the effects of calorie restriction.4
(H)optimize Your CellsXanthohumol, another hops compound, has been shown to help prevent the initiation, promotion, and progression stage of carcinogenesis.5 Among xanthohumol's properties are inhibition of cyclooxygenase-1 (COX-1) and COX-2 enzymes, which have inflammatory effects, as well as an ability to scavenge reactive oxygen species. When tested in cultured mouse mammary gland tissue, xanthohumol prevented carcinogen-induced precancerous lesions.
Another investigation of the effects of xanthohumol, isoxanthohumol, and 8-prenylnaringenin found an ability to decrease estrogen synthesis.6 In prostate cancer cells and benign prostate hyperplasia cells, xanthohumol decreased cell viability, increased apoptosis, and dampened the activation of nuclear factor-kappa beta which, when dysregulated, has been associated with cancer, inflammation, and other conditions.7 In human colon cancer cells, treatment with xanthohumol also induced apoptosis by downregulating an anti-apoptotic protein and activating caspases.8
Hops for Menopausal WomenThe first prospective, randomized, double-blind, placebo-controlled study of the ability of hop extract to alleviate some of the symptoms of menopause was reported in 2006.9 Sixty-seven menopausal women received a standardized hop extract or a placebo for 12 weeks. By six weeks, hot flash scores were reduced in women who received hops in comparison with the placebo. Interestingly, a lower dose of hops extract was more effective than a higher dose.
In ovariectomized rats that exhibited elevated skin temperature caused by estrogen withdrawal, as an animal model of menopausal hot flushes, 8-prenylnaringenin from hops reduced the animals' skin temperature after just two days of treatment.10 The effect was blocked by simultaneous administration of an estrogen receptor antagonist.
Results of a randomized trial of menopausal women reported in 2010 suggested superiority of a standardized hop extract in comparison with a placebo.11 The authors of the report conclude that: "[…]phytoestrogen preparations containing this standardized hop extract may provide an interesting alternative to women seeking relief of mild vasomotor symptoms."
Another randomized trial, reported in 2016, that compared the effects of hops to a placebo in women with early menopausal symptoms found a significantly lower number of hot flashes in hops-treated women and improved average Greene score (an assessment of menopausal symptoms) at 4, 8, and 12 weeks.12
Ovariectomized female rats given hops extract demonstrated increased sexual motivation.13 Since low libido is a frequent menopausal complaint, hops could be worth trying by women with this symptom.
Another menopausal complaint is poor sleep. A study of nurses who worked rotating or night shifts experienced better nighttime sleep quality after drinking nonalcoholic beer containing hops at dinnertime for fourteen days.14 Participants also reported a decrease in anxiety. Similar effects were found in university students who consumed nonalcoholic beer with dinner.15
Your Brain on HopsHops also show promise against another age-related condition: Alzheimer's disease. Screening of over 1,600 plant extracts by Japanese researchers resulted in the identification of hops as having the ability to inhibit amyloid beta, the toxic protein that accumulates in the brains of individuals afflicted by Alzheimer's disease.16
In a mouse model of Alzheimer's disease, the researchers found that animals that received drinking water to which hops extract was added had decreased amyloid beta deposits in their brains and less memory impairment at 9 and 12 months than untreated mice.
Based on these findings, drinking beer in moderation may not be as bad as some have made it out to be. However, it's not necessary to increase one's alcohol intake to obtain the benefits of hops. Nonalcoholic beer and hops extract can be consumed on a regular basis without the concerns associated with alcoholic beverages.
- Milligan SR et al. J Clin Endocrinol Metab. 1999 Jun;84(6):2249-52.
- Milligan S et al. Reproduction. 2002 Feb;123(2):235-42.
- Wang J et al. Zhong Yao Cai. 2004 Feb;27(2):105-7.
- Callemien D et al. J Agric Food Chem. 2005 Jan 26;53(2):424-9.
- Gerhäuser C et al. Mol Cancer Ther. 2002 Sep;1(11):959-69.
- Monteiro R et al. J Agric Food Chem. 2006 Apr 19;54(8):2938-43.
- Colgate EC et al. Cancer Lett. 2007 Feb 8;246(1-2):201-9.
- Pan L et al. Mol Nutr Food Res. 2005 Sep;49(9):837-43.
- Heyerick A et al. Maturitas. 2006 May 20;54(2):164-75.
- Bowe J et al. J Endocrinol. 2006 Nov;191(2):399-405.
- Erkkola R et al. Phytomedicine. 2010 May;17(6):389-96.
- Aghamiri V et al. Complement Ther Clin Pract. 2016 May;23:130-5.
- Di Viesti V et al. J Ethnopharmacol. 2011 Mar 24;134(2):514-7.
- Franco L et al. PLoS One. 2012;7(7):e37290.
- Franco L et al. Acta Physiol Hung. 2014 Sep;101(3):353-61.
- Sasoaka N et al. PLoS One. 2014 Jan 29;9(1):e87185.
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