Hops (the fruiting bodies of the hop plant) is most famous as the source of beer's bitter flavor, but it has a long history of use in herbal medicine as well. In Greece and Rome, hops was used as a remedy for poor digestion and intestinal disturbances. The Chinese used the herb for these purposes and to treat leprosy and tuberculosis.

As cultivation of hops for beer spread through Europe, it gradually became obvious that workers in hop fields tended to fall asleep on the job, more so than could be explained by the tedious work. This observation led to enthusiasm for using hops as a sedative. However, subsequent investigation suggests that much of the sedative effect seen in hop fields is due to an oil that evaporates quickly in storage.

Despite the absence of this oil, dried hop preparations do appear to be somewhat calming. While the exact reason is not clear, it seems that a sedating substance known as methylbutenol develops in the dried herb over a period of time.1 It may also be manufactured in the body from other constituents of dried hops.

Germany's Commission E authorizes the use of hops for "discomfort due to restlessness or anxiety and sleep disturbances." However, scientists have had difficulty proving that hops causes sedation.2 Because its sedative effect is mild at most, the herb is often combined with other natural treatments for anxiety and insomnia, such as valerian. One small, double-blind study found evidence that a proprietary combination of hops and valerian extract is more effective as a sleep aid than placebo; the results of this trial also hint that hops plus valerian is more effective than valerian alone, but this possible finding did not reach statistical significance.9

In addition, hops has fairly strong estrogen-like properties, making it a phytoestrogen.5-8 The basis for this activity is a constituent called 8-prenyl naringenin. Like soy (another phytoestrogen), hops has been proposed as a treatment for menopausal symptoms. It is also marketed as a breast enhancement product. However, there is no direct evidence as yet that it works for either of these purposes.

For reasons that are not at all clear, a water extract of hops (called “hop water”) has shown promise for reducing allergic reactions.10,11,12In a small, double-blind, placebo-controlled study, use of hop water at a dose of 100 mg daily significantly reduced symptoms of allergy to the Japanese cedar.11 (The Japanese cedar is a strong allergen, similar in its sensitizing power to ragweed.)

A special extract of the hop plant called “hop bract polyphenols” has shown promise for preventing cavities and treating or preventing periodontal disease.13

Like other bitter plants, hops is also used to improve appetite.