Fennel, sometimes called fennel seed, sweet fennel, fenkel, or its botanical name Foeniculum vulgare, is a perennial herb of the Apiaceae (carrot) family (1). Fennel has greyish-green, thread-like feathered leaves and yellow flowers attached to the stem (2). Fennel is native to southern Europe and Asia Minor but is considered invasive in Australia and parts of the United States (3). Fennel is grown for its edible shoots (stems, leaves, buds, and flowering stems) and seeds, commonly used for culinary and medicinal purposes.

Fennel is cultivated worldwide, and its seeds are gathered in the fall. If you plan to forage for fennel, always harvest ethically. Never collect anything from private property without direct permission. When harvesting from public spaces, consider the impacts on native plant populations. Due to the uncertainty of surrounding plants, be careful not to disturb them, as they could be endangered or threatened species. Always be kind to the earth and only harvest what you need.

According to one of my favorite herbal resources, the Encyclopedia of Herbal Medicine, fennel seeds’ key constituents are volatile oil (about 80% anethole, plus fenchone and methylchavicol), flavonoids, coumarins (including bergapten), and sterols.

Research-Backed Health Benefits of Fennel

Fennel is often used in culinary arts, but it also has impressive health benefits, such as:

Highly Nutritious

The human body needs nutrients to flourish. Without vital vitamins and minerals, it won’t function properly. Thankfully, fennel’s most widely used part of the plant, its seeds, are highly nutritious. They are known for their omega-6 fatty acids, potassium, calcium, phosphorus, magnesium, vitamins A and C, fiber, and more (4). Although fennel has some protein, it is not a high-protein food and only contains approximately 1 gram of protein per cup of fennel seeds.

Antibacterial Properties

An antibacterial property is when a substance, or in this case, an herb, can destroy or suppress the growth and reproduction of bacteria (5). Fennel contains certain compounds that have potent antibacterial properties. One study found that fennel extract’s phenolic compounds inhibit the growth of bacteria and yeasts, as well as high antiglycation activity (6). Another study found fennel essential oil was most effective against gram-positive bacteria and more effective than commercial Ampicillin (penicillin) antibiotics (7).

Anti-Inflammatory Properties

Although inflammation is a natural bodily response, chronic inflammation can lead to detrimental health effects. Chronic inflammation has been linked with many diseases, such as type 2 diabetes, asthma, and certain cancers (8). Fennel has an extensive array of inflammation-fighting plant compounds. For instance, fennel’s antioxidant compounds can help reduce inflammatory marker levels, much like vitamin C and quercetin do (9). One study concluded that cumin and fennel volatile oils suppressed neutrophil activation, which supports the response of other immune cells and may be beneficial against neutrophilic inflammatory diseases (10,11).

May Improve Digestion

Your diet is vital to your health, but so is being able to digest it properly. Unfortunately, digestive diseases affect approximately 60 to 70 million people in the United States (12). Thankfully, fennel is rich in volatile oils that help the gut soothe and remove gas from the digestive tract, making it a carminative herb (13). Between being a carminative herb and its anti-inflammatory properties, fennel is great for improving overall digestion. One study found that supplementing dietary fennel seed powder enhances appetite, digestion, nutrient absorption, and immunity (14). Additionally, fennel seeds’ antioxidants help reduce gas and increase intestinal muscle movements (15). 

May Support Heart Health

Unfortunately, heart disease is the world’s number one cause of death (16). Due to the incredibly complex determinants of heart disease and various possible contributions, it’s hard to pinpoint an exact way to prevent it. Still, we can at least take steps to lower our overall risk. Thankfully, fennel and its seeds can positively impact heart health.

Fennel’s high fiber content is likely responsible for its heart health benefits. Although dietary fiber (predominantly found in fruits, vegetables, whole grains, and legumes) is best known for preventing or alleviating constipation, it can also provide other health benefits. Fiber can aid in maintaining a healthy weight and decreasing the risk of diabetes, heart disease, and some types of cancer (17). Studies have estimated that for every 7 grams of fiber consumed per day, heart disease risk decreases by 9 percent (18). Another study noted slight positive changes in LDL, HDL, and triglyceride levels following short-term fennel supplementation (19).

May Provide Menopause Symptom Relief

Menopause transpires 12 months after a woman’s last menstrual cycle when estrogen levels decrease. In the years leading to menopause, women may have changes in their menstrual cycle and experience hot flashes or other uncomfortable symptoms (20). A study review found fennel’s plant compounds influential in relieving hot flashes, vaginal itching, dryness, dyspareunia (painful intercourse), sexual function, sexual satisfaction, and sleep distribution associated with menopause (21). Another study noted that fennel seed significantly reduced the severity of menopausal symptoms but did not significantly improve sexual desire in postmenopausal women (22).

May Increase Breastmilk Supply

Lactation occurs when hormonal changes signal the mammary glands to make milk in preparation for a baby (23). Fennel’s plant compound, which relieves menopausal symptoms, may boost breastmilk production, too. Fennel has demonstrated galactogenic properties, meaning it increases breastmilk secretion. Research has found that fennel’s plant compound, anethole, has dianethole and photoanethole, which are responsible for the galactogenic effects (24). Additionally, fennel may improve prolactin levels (the hormone that signals the body to produce breast milk), increasing milk secretion (25).

Anticancer Properties

Statistics say that 158.3 of every 100,000 individuals will die from cancer, but what if they didn’t have to (26)? Thankfully, one of the main active compounds in fennel seeds, anethole, has exhibited anticancer properties. Several studies have been conducted in-vitro (test tubes) and on animals regarding fennel’s potential anticancer properties. One test-tube study observed anethole’s ability to suppress growth and induce apoptosis (cell death) in human breast cancer cells (27). Another test-tube study found that fennel extract stopped the spread of human breast cancer cells and induced cancer cell death (28). In animal studies, fennel seed extract even demonstrated the ability to protect against breast and liver cancer (29).

Safety Information, Contraindications & Interactions

Mainstream sources claim fennel is possibly unsafe when breastfeeding. They claim reports of breastfeeding infants with damage to their nervous systems after exposure to fennel tea via breastmilk (30). I first thought there were likely other factors at play, similar to the study where they blamed lavender for endocrine disruption in boys, yet fragrance was likely the cause. So, I decided to research fennel use with infants.

I thoroughly searched the internet but came up empty-handed. The best I could find was a study from 1994, but every version was blank (31,32,33). I continued to dig and found one source that said the herbal tea mixture reportedly contained licorice, fennel, anise, and goat’s rue (34). Although this may not ease your mind, I did find a study demonstrating the superiority of fennel seed oil emulsion compared to placebo when decreasing the intensity of infantile colic, and no side effects were reported (35).

Additionally, trusted herbalist Richard Whelan reports no adverse effects are expected (or have ever been reported) from taking fennel in tea or tincture, even in high or frequent doses. In his professional opinion, fennel can be safely taken by the young, old, breastfeeding, or pregnant (36).

If you read my post How to Practice Essential Oil Safety, you know aromatherapist Wendy Robbins states that essential oils should never be taken internally or applied undiluted. She warns that fennel seed essential oil may interact with medication and inhibit blood clotting. She cautions against using oxidized oil topically as skin sensitization is more likely to occur. She also mentioned contraindications for pregnancy, breastfeeding, endometriosis, estrogen-dependent cancers, and children under five. The recommended dermal maximum for fennel essential oil is 2.5% (37).

How To Use Fennel & Product Recommendations

When I make homemade herbal remedies, I try to buy herbs locally. When buying locally isn’t an option, I typically purchase from one of the following brands I trust:

• Anthony’s Goods
• Frontier Co-op
• Starwest Botanicals

Looking for additional herbal suppliers? Check out my post, 3 Ways to Source Herbs.

I haven’t had the opportunity to make herbal remedies with fennel, but I enjoy a few premade herbal products, including:

• Gaia Herbs’ Lactation Support helps promote healthy milk volume production while nursing. These convenient vegan liquid phyto-capsules feature organic marshmallow root, fenugreek seed, fennel seed, and raspberry leaf for at-home or on-the-go support.
• Herb Pharm’s Fennel Extract is expertly extracted to support the digestive system. Prepared from the certified organic mature seed of Foeniculum vulgare plants, this gluten-free and non-GMO, alcohol-based tincture is rapidly absorbed. 
• Plant Therapy’s Sea Fennel Essential Oil has a sweet, spicy, earthy scent that is a favorite for relieving digestive problems and menstrual discomfort. The unique aroma of Fennel is excellent for easing worries without creating sleepiness. 
• Plant Therapy’s Sweet Fennel Essential Oil improves skin tone and radiance while helping to reduce the appearance of dimples and ripples. It is also a good choice for digestive issues and beneficial during seasonal illnesses and respiratory concerns.
• The Brothers Apothecary’s Cosmic Cleanse helps you elevate, starting with the body and peaking with mind and spirit. Crafted with antioxidant-rich CBD Rooibos tea and stomach-soothing herbs, this tea is brewed for a better you. Gentle, naturally sweet, and slightly nutty, this blend is easy to drink and impossible not to love.
• The Brothers Apothecary’s Digest Well focuses on settling the stomach, supporting a healthy immune system, and relieving the body of occasional aches and pains — all in one capsule.

Product Disclaimer

Product recommendations are affiliate links. I do not own or make these products. Recommendations are selected according to ingredients at the time article was written and can change at any time. I encourage you to double-check ingredients and research each company to ensure they’re suitable for your journey.

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