Fennel is a flavorful plant used extensively in herbal medicine and in cooking. The plant's fibrous bulb acts as a delicately sweet vegetable, while its seeds are used as seasonings and supplements. Fennel owes its licorice-like flavor to the compounds anethole, dianethole and photoanethole, which are chemically and structurally similar to the hormone estrogen. Fennel's exact effects on the human body are poorly understood, but it does appear to appreciably alter levels of reproductive hormones in people using large amounts of the supplement.
Composition and Safety
Fennel contains a complex of estrogen-affecting compounds. A 1980 evaluation published in the "Journal of Enthnopharmacology" concluded that fennel's primary estrogen-like compounds include anethole, photoanethole and dianethole, which it shares with similar-tasting plants, such as licorice root, anise and star-anise. When used in food quantities as flavoring agents, these compounds are classified as GRAS, or generally recognized as safe, by the Food and Drug Administration. This implies that the compounds can be used in moderate amounts without posing a safety risk to most healthy human beings.
Estrogenic Effects and Cancer
Estrogen-like plant compounds, such as those found in fennel, have a notable effect on human hormones. The "Journal of Ethnopharmacology" notes fennel's extensive history of use as a treatment for lactation problems, infertility and pregnancy complications. The "Journal of Integrative Cancer Therapies" notes that these compounds have "clinically significant" effects and may be either harmful or beneficial to women with estrogen-sensitive conditions such as breast cancer and ovarian cancer. However, scientists are not yet certain of whether these hormonal effects are beneficial or detrimental to women with these disorders.
Fennel and Breast Development
Herbal supplement manufacturers frequently advertise fennel, without FDA approval, as a natural breast enhancer. Mayo Clinic physician Sandhya Pruthi strongly urges against the use of these products, noting that there is insufficient evidence of their safety or efficacy. It is, however, plausible that fennel's estrogen-altering can increase breast size. Renowned lactation expert Kelly Bonyata recommends the herb to nursing women as a galactagogue, or breast milk enhancer. When given fennel tea as a colic remedy, many babies have experienced thelarche, or premature breast development, according to the "Journal of Pediatric Surgery." These findings suggest that medicinal amounts of fennel affect breast tissue.
Potential Dangers
Fennel used as a food does not generally cause side effects or notable changes in hormone levels. However, medicinal quantities may pose a danger. In addition to causing alarming development of secondary sex characteristics in children, large quantities of fennel can also increase the risk of some forms of cancer. The FDA's GRAS assessment of anethole -- the chief estrogenic component of fennel -- acknowledged that rats ingesting large quantities of anethole experience a greater risk of liver tumors and liver failure. Fennel's hormonal effects could also influence fertility, pregnancy and hormone-sensitive cancers. Until scientists understand more about fennel's pharmacological effects, do not use fennel without consulting a qualified medical practitioner.
References
- "Journal of Ethnopharmacology"; Fennel and Anise as Estrogenic Agents; M.Albert-Puleo; December 1980
- "Food and Chemical Toxicology"; The FEMA GRAS Assessment of trans-Anethole Used as a Flavouring Substance; P. Newberne et al.; July 1999
- "Integrative Cancer Therapy"; Phytoestrogens in Botanical Supplements -- Implications for Cancer; C.E. Piersen; June 2003
- "Journal of Pediatric Surgery"; A Striking and Frequent Cause of Premature Thelarche in Children -- Foeniculum Vulgare; Z. Turkyilmaz et al.; November 2008
- Kellymom.com; Fennel; Kelly Bonyata
- MayoClinic.com: Natural Breast Enhancement -- Is it Safe?
