Fennel, the licorice-flavored Mediterranean vegetable, has a long folk tradition as a remedy for women’s health issues. Traditional uses include helping new mothers produce more breast milk, easing premenstrual discomfort—and relieving common menopausal symptoms.

Fennel for hot flashes? When you understand how fennel affects the body, it makes sense—and a new study finds that it can help. But is it ready for prime time?

Background: Fennel, especially oil-rich fennel seeds, is rich in phytoestrogens, which act in some ways like estrogen in the human body. That estrogenic effect is likely key to fennel’s effects on menstruation and breastfeeding. For women experiencing bothersome menopausal symptoms who are either not candidates for pharmaceutical hormone treatment or who simply prefer to use nondrug remedies, phytoestrogenic plants such as fennel may provide symptomatic relief. But few clinical studies have looked specifically at fennel for menopause.

Study: Researchers from Iran conducted a randomized, placebo-controlled study including 90 women who were within the first five years of menopause. The women were given capsules containing either fennel essential oil or an identical-looking placebo capsule containing sunflower oil. The fennel capsules used in the study contained between 71 and 90 milligrams of anethole, one of fennel oil’s primary compounds, which has established estrogenic properties. Neither the women nor the researchers knew which women received the capsules containing fennel oil and which received the placebo.

At the beginning of the study and at several points during and afterward, all the women completed Menopause Rating Scale (MRS) questionnaires, which assess the severity of 11 menopausal symptoms including sleep disturbances, hot flashes, irritability, vaginal dryness and others. Women took their capsules every day for eight weeks, and the final MRS questionnaire was completed at 10 weeks. Before starting the study, the average MRS score, on a scale of 0 to 44, was 20. That’s moderately high.

Results: Fennel eased menopausal symptoms. For women who got the fennel capsules, MRS scores dropped to nine, on average, in eight weeks, then edged up to 13 at the end of the study. For those taking placebo pills, MRS scores stayed at 19, on average, throughout the study. At any given time, women who received fennel capsules had statistically significant improvements in their MRS scores compared with their baseline scores. For those taking placebo pills, there was no statistically significant change. (The study doesn’t specify which of the 11 menopausal symptoms were most improved by the fennel treatment.) Side effects were rare and minor, including one low-level allergic reaction.

Bottom line: This was a small, short-term study, but it provides evidence that fennel is a candidate for nondrug menopausal relief. One other eight-week placebo-controlled study found similar benefits (fennel was combined with St. John’s wort in this case), and another study found that fennel-based vaginal cream was effective for vaginal dryness related to menopause. But even such “natural” treatments that affect estrogen need to be considered with care—and this latest study is too short-term to yield important information about long-term risks and benefits. Women who have survived hormone-related cancers, for instance, may be advised by their doctors to avoid concentrated plant phytoestrogens such as the anethole found in fennel oil.

For perspective on this new research, we went to naturopathic physician Holly Lucille, ND, RN, author of the Bottom Line blog “The Natural Side of Menopause.” While fennel extract can work well for menopausal symptoms in combination formulas with other phytoestrogenic compounds, she said, she’s not likely to prescribe fennel as a stand-alone supplement. One reason is that we still don’t know, even with this new study, which menopausal symptoms—hot flashes, say, or vaginal dryness—a fennel supplement might be best at relieving. So Dr. Lucille is much more likely to prescribe botanical medicines that have more evidence for specific menopausal complaints. (To find out which ones she likes best, see her latest blog post, “Plant Power for a Smooth Menopause.”)

If you’re interested in combination supplements that include concentrated fennel seed oil, discuss your options with your doctor. What about eating fennel—or cooking with fennel seeds? That won’t give you a strong dose of phytoestrogens…it’s just tasty.

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