Fennel, a dill-like member of the carrot family, offers a variety of medicinal and culinary uses. The seeds of the plant, which contain a high concentration of medicinally potent volatile oils, have a strong aroma similar to licorice or anise. According to Drugs.com, the oils of these richly aromatic seeds can repel insects, enhance cosmetics and improve the flavor of desserts. Fennel seeds are also used in botanical medicine; they show some benefits for treating gastrointestinal discomforts and other common complaints. However, fennel's medicinal compounds are not fully understood and may cause unpleasant or dangerous side effects.
Benefits
In herbal medicine, fennel seeds are commonly used as carminative agents; they help reduce the size of gas bubbles in the colon. Because of this property, fennel is a popular treatment for irritable bowel syndrome and infant colic. The lactation website Kellymom.com also notes that fennel is traditionally used as a galactagogue, or agent to promote breast-milk production. Many herbal breast enhancers--generally designed for women who are not nursing--also contain fennel seeds because of their ability to stimulate breast growth. In theory, fennel's hormonal effects may also be useful for women experiencing menopausal symptoms, such as hot flashes and low libido.
Effects
Scientists do not fully understand fennel's effects on the human body; however, preliminary evidence yields some clues regarding the plant's chemical composition. Kellymom.com notes that fennel seeds, like many other medicinal plants, contain phytoestrogens. These natural plant compounds are chemically similar to estrogen, a key hormone responsible for regulating functions in the female body. Phytoestrogens in fennel seed may stimulate the let-down reflex, menstruation, breast development and increased libido; in men and children, they may even have a feminizing effect. The natural oils in fennel seed also seem to enhance digestion and to provide a mild stimulant effect; this partially explains fennel's efficacy as a treatment for colic in babies.
Considerations
Along with other soothing medicinal herbs, such as chamomile and ginger, fennel seed is a common ingredient in "gripe water" formulas designed to improve a baby's digestion. These home remedies are generally recognized as safe, and they are associated with few side effects and no known drug interactions. However, the medical journal Pediatric Surgery warns that children who take fennel regularly can develop thelarche, or premature breast development. Nevertheless, Pediatric Surgery notes that these cases have been documented only in children taking fennel for extended periods of time. Additionally, while fennel seems to enhance breast-milk production when it is used in moderate amounts, Kellymom.com explains that the phytoestrogens in fennel seeds may actually reduce milk supply if it is overused.
Warning
Although teas and aqueous extracts of fennel seed are safe in moderate amounts, the plant's essential oil is acutely toxic and not safe for internal use. Drugs.com notes that fennel-seed oil offers a number of practical applications; it helps repel insects and fungi, and it is a useful scenting agent for cosmetics. However, taken internally, fennel oil is a neurotoxin--it may cause seizures, hallucinations or respiratory problems. Fennel-seed oil may be applied to the skin as a perfume, insect repellent or breast enhancer, but herbalists do not generally recommend it for internal use.
Solution
Experts offer several guidelines for the safe, effective use of fennel seeds. For infants and children, fennel-seed teas and aqueous extracts can help relieve gas and colic pain. The journal Pediatric Surgery recommends limiting the use of these preparations, because excessive use can cause premature breast development. Breastfeeding women may stimulate breast-milk production using topical oil applications or moderate amounts of fennel-seed tea. Drugs.com advises that a traditional dose of 5 to 7 grams of fennel seed appears to be safe for adults. As always, talk to a qualified practitioner before using fennel to treat any medical condition. Promptly report any adverse reactions to your healthcare provider.
Member Comments