Hops (the fruiting bodies of the hop plant) is most famous as the source of beer's bitter flavor. However, it also has a long history of use in herbal medicine as well. Its most common herbal use today is as a mild sedative, possibly helpful for anxiety and insomnia . In addition, hops has a constituent with strong estrogen-like properties, and for that reason it has been proposed as a treatment for menopausal symptoms. However, neither of these proposed uses is supported by reliable scientific evidence.
In recent years, an entirely novel and rather surprising potential use of hops has come to light: treating hay fever.
For reasons that are not at all clear, a water extract of hops (called, unsurprisingly, “hop water”) may reduce allergic reactions. The first evidence came from an animal study performed in Japan in 2005. Based on these results, as well as a subsequent animal studies, Japanese researchers conducted a double-blind, placebo-controlled human trial.
In this study, 39 people were given a daily drink containing either 100 mg of hop water or placebo. All of these study participants were known to have allergies to the Japanese cedar. This plant is a strong allergen—as famous in Japan for causing hay fever symptoms as ragweed is in the US.
The results of this small trial were promising. Over the weeks of the study, use of the hop water extract significantly reduced nasal symptoms as compared to placebo.
Note that this level of evidence has to be classified as “preliminary.” Larger studies (particularly, studies conducted by researchers not connected to any hop water product) will be necessary to establish whether this reported benefit is real.