History and Origin
Fennel consumption dates back to the ancient times, being used in the Mediterranean region since then. Roman gladiators used fennel to increase their power. This plant has been used to control weight gain. Its Greek name “marathon” meaning “staying slim” expresses people's belief about the effect of fennel on appetite decrement. The Marathon Plain means the Fennel Plain. After the war, the Greeks have used woolen stems of the fennel as a sign of victory.
Fennel Health Benefits
1. Reducing Appetite
In a study published in the Journal of Clinical Nutrition Research, researchers have explored the effect of fennel on appetite decrement. The results of this study have shown that drinking fennel tea reduces hunger and increases satiation in the over-weighted women. Trans-Anethole, a compound in fennel oil, affects appetite control. It has a similar structure to catecholamine (a type of neurohormone) and its effect on appetite control is similar to amphetamine (an appetite suppressant).
2. Improving Digestive System Function
Modern scientific studies on the properties of fennel seeds are showing that their rich volatile oil content is primarily responsible for these digestive benefits and ability to clear intestinal gas so effectively. Anethole, Fenchone and Estragole have such anti-spasmodic and anti-inflammatory properties that calm the intestinal muscles and prevent bloating. It is observed that fennel tea has a good therapeutic effect on IBS. It is also effective in baby colic treatment. A study published in Journal of Alternative Therapies in Health and Medicine (2003) demonstrated that feeding babies suffering from baby colic with fennel seed oil decreases intensity of its symptoms.
3. Improving Liver Function
A study published in the Global Journal of Environmental Science and Technology has investigated the effect of Chlorpyrifos (CPF) on liver and fennel seed essential oil on eliminating this toxicity in male rats. The hepatotoxicity-induced and healthy rats were given the essential oil for 28 days. The results have shown that using CPF leads to lipid peroxidation increment, changing the number of some biomarkers including aminotransferase (ALT), acid phosphatase (ACP), cholinesterase (ChE) and gamma-glutamyl transferase (GGT) towards the normal value. This beneficial effect of fennel may be due to its antioxidant activity. The protective effect of this plant on the liver is due to di-limonene and beta-myrcene. In addition, di-limonene provides a chemoprotective effect against cancerous liver cells.
4. Calming Anxiety and Stress
In a study published in the journalof BMC Complementary and Alternative Medicine, the fennel extract reduced the mouse anxiety. According to researchers, fennel extract is effective in the treatment of estrogen deficiency disorders. Essential oil of Fennel exerts its anti-anxiety effect through GABA-A/benzodiazepine receptor complex.
5. Anti-Microbial
Some fennel compounds, such as phenylpropanoid derivatives, have antibacterial properties. Dillapiole is the active antimicrobial component in the fennel stem. Scopoletin, a derivative of Coumarin, is extracted from fennel and has an antimicrobial effect. Fennel essential oil also has anti-fungal compounds. It has been shown that these compounds provide a complete inhibitory effect on Aspergillus and Fusarium fungus.
6. Improving Memory Function
In 2006, an investigation was conducted to assess the potential of fennel extract as a memory enhancer (nootropic) and cholinesterase inhibitor in mice. Using the methanolic extract of fennel improved the memory deficits due to aging after eight successive days. Another study on the effects of fennel on memory performance in rats showed that fennel extract had an inhibitory effect on acetyl cholinesterase. According to researchers, fennel may be used as a treatment to cognitive impairments such as dementia and Alzheimer.
7. Improving Respiratory Tract Function
A bronchodilator effect could be seen in guinea pigs using ethanolic extract and essential oil of fennel. The effect of fennel on opening potassium channels may be the reason to relieve the Trachealis muscle in guinea pigs. Also, the structural similarity of fennel anethole to Norepinephrine, epinephrine and dopamine may be another reason for this effect.
8. Increasing Breast Milk Production
Researchers found that fennel increases serum levels of prolactin (the essential hormone for breastfeeding) in breastfeeding mothers significantly. According to a syudy published in The Iranian Journal of Obstetrics, Gynecology and Infertility. Milk production begins with combining this hormone with the receptors of the milk-producing cells. In mothers who took capsules containing fennel powder, increased levels of prolactin were observed.
9. Relieving Menstrual Pain
Researchers of Shahid Beheshti University have reported the positive effect of essential oil of fennel on reducing the severity of primery dysmenorrhea in young girls. Based on the results of other studies, fennel can reduce the frequency and severity of uterine contractions. Due to the fact that prostaglandin causes muscle flattening of the uterus and causing colic pain, utilizing a spasmolytic drug is effective on pain decrement. This possible mechanism of fennel may be related to its spasmolytic nature. The anethole of fennel is structurally similar to dopamine and therefore attaches to dopamine receptors and alleviates the severity of pain.
The effect of fennel in alleviating menstrual pain is like Mefenamic acid. In an experiment, the effect of fennel on primery dysmenorrhea was investigated and its results were published in the International Journal of Gynecology & Obstetrics. Seventy women (15–24 years old) were divided into three groups: control group, Mefenamic acid (every 6h, 250mg orally) and essential oil of fennel with 2% concentration (every four hours, 25 drops, orally). The results showed that both fennel and Mefenamic acid were effective in reducing pain compared to the control group, but the effects of Mefenamic acid started earlier. However, a case of increased in the amount of menstrual flow was reported in this test. As a result of this study, fennel can be used as an effective and safe herbal medicine for primary dysmenorrhea, although its effect may be less than mefenamic acid in the dosages used for this study.
10. Increasing Fertility
The fennel provides estrogenic, anti-inflammatory and antioxidant effects. Researchers of the University of Kharazmi, Tehran, found that fennel may be effective in treatment of the patients with polycystic ovary syndrome by increasing the serum concentration of follicular stimulatory hormones in mice. Many researchers attribute the effect of fennel on female sex hormones to its anethole and believe that the anethole polymers (such as di-anethole and foto-anethole) are phytoestrogens. The important point is the fact that men should not over-consume the fennel as it may increase estrogen and thus reduce spermatogenesis and reproductive activity in them.
11. Regulating Blood Glucose Levels
The Macedonian Journal of Medical Science published a study in evaluating the effects of essential oils of fennel on blood glucose reduction. In this study, rats got diabetic with Streptozotocin and their physiological changes were investigated. Then, they were fed by essential oils of fennel and their diabetic physiological traits were again evaluated. It was observed that streptozotocin caused poisoning of beta cells in the pancreas and increased the amount of active oxygen species by inducing some metabolic processes. It also prevented the activity of free radicals destroying enzymes. This test showed that the effect of diabetes on the pancreas of rats was eliminated with fennel oil consumption, which is an effect of fennel due to its antioxidant properties. In diabetic rats using fennel oil, cell regeneration was observed in Pancreas Islets of Langerhans. So, the repair of this tissue is due to the consumption of fennel due to the restorative effect of extracellular pancreatic cells, which shows the positive effect of this substance on insulin production.
12. Regulating Blood Cholesterol Levels
According to a study published in the American Journal of Food Technology, the consumption of fennel methanolic extract with a decrease in bad cholesterol and increase in good cholesterol levels improved blood lipid profiles in high-fat diet-induced obese rats. This could be explained as fennel methanolic extract seeds could significantly increase HDL level. This type of lipoprotein could stimulate the reverse cholesterol transport from the blood stream to the liver. Furthermore, it has been shown that fennel could delay upper gastrointestinal transit which promotes a decrease in fat and sugar absorption.
13. Improving Cardiovascular System Function
Nitrites play a major role in the cardiovascular system. Fennel seeds contain high levels of nitrites, and in the experiment, its extract increased the nitric oxide production in-vitro. It has also been observed that the methanolic extract of fennel has anti-atherogenic properties and reduces the amount of lipid in the blood plasma. In this experiment, fennel reduced the level of triglycerides in the fatty liver and, by decreasing the accumulation of fat in the vessels, facilitated the blood flow in the coronary arteries. The results show that fennel can be effective in controlling cardiovascular disorders due to its effects on blood fat decrement and anti-ergogenic properties. Also fennel extract significantly reduced blood pressure, without affecting the heart rate and respiration.
What Are Fennel Side Effects?
1. When taken by mouth: Generally, health risks or side effects following the proper administration of designated therapeutic dosages are not recorded.
Note: Allergic reactions following intake of fennel have been only very rarely observed.
2. Pregnancy: Not enough is known about the safety of using fennel during pregnancy. It's best to avoid use.
3. Breast-feeding: Before taking fennel, consult your healthcare provider.
4. Bleeding disorders: Fennel might slow blood clotting. Taking fennel might increase the risk of bleeding or bruising in people with bleeding disorders.
5. Hormone-sensitive condition such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Fennel might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, do not use fennel.
6. Children: Preparations, excluding the herb itself and tea infusions are not to be administered to small children.
7. Allergy to celery and carrot: Fennel might cause an allergic reaction in people who are sensitive to these plants.
Generally, every person may be allergic to certain herbs and spices. This sensitivity must be first diagnosed by the person and secondarily by the physician. However, these allergic reactions do not cause chronic or acute side effects, and after identifying the allergenic plant and removing it from the diet, allergy-related complications will be eliminated. No company or product can be aware of the allergic reactions of different bodies in advance. The body's incompatibility with one or more specific herbs rarely occurs, but consumers may encounter it anyway.
Fennel Daily Dosage
5-7 grams per day.
Bioactive Compounds
- Essential oil (Trans-Anethole, Fenchone, Limonene, Camphor, Alpha-Pinene);
- Fixed oil (Petroselinic acid, Oleic acid, and Tocopherols);
- Flavonoids (Quercetin 3-Glucuronide, Isoquercetin, Kaempferol 3- Glucuronide, and Kaempferol 3-Arabinoside).
Best Time to Consume
1-2 hours before or after meals.
Possible Drug Interactions
1. Birth control pills (Contraceptive drugs): Some birth control pills contain estrogen. Fennel might have some of the same effects as estrogen. Taking fennel along with birth control pills might decrease the effectiveness of birth control pills. Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone.
2. Ciprofloxacin (Cipro): Ciprofloxacin (Cipro) is an antibiotic. Fennel might decrease how much ciprofloxacin (Cipro) the body absorbs. To avoid this interaction take fennel at least one hour after ciprofloxacin (Cipro).
3. Tamoxifen (Nolvadex): Some types of cancer are affected by hormones in the body. Estrogen-sensitive cancers are cancers that are affected by estrogen levels in the body. Tamoxifen (Nolvadex) is used to help treat and prevent these types of cancer. Fennel seems to also affect estrogen levels in the body. Taking fennel along with tamoxifen might decrease the effectiveness of tamoxifen (Nolvadex). Do not take fennel if you are taking tamoxifen (Nolvadex).
4. Estrogens: Large amounts of fennel might have some of the same effects as estrogen. But fennel isn't as strong as estrogen pills. Taking fennel along with estrogen pills might decrease the effects of estrogen pills. Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol and estradiol.
Traditional Use
Fennel has been used, in traditional medicine for treatment of stomach disorders such as gastric and spasmodic disorders, feelings of satiation and bloating and upper respiratory tract damage. Fennel honey is used to treat upper respiratory tract damage in children.
Some Questions about Fennel
What is fennel seeds good for? / What are the benefits of fennel seeds?
In traditional medicine, fennel seeds have been used for conditions affecting the respiratory, reproductive, endocrine, and digestive systems. It is also used as a galactagogue by nursing mothers.
Furthermore, properties of fennel were demonstrated in several studies, such as:
- antimicrobial & antipyretic
- antinociceptive & relieving menstrual pain
- antispasmodic & promoting gastrointestinal motility
- improving respiratory tract function
- hepatoprotective
- hypoglycemic
- hypolipidemic
- memory enhancing property and more
According to researchers, the herb has potential use for the development/formulation of new drugs and clinical usage.
What does fennel seed taste like?
Fennel (Foeniculum vulgare Mil.) fruits have a mild, sweet taste and a spicy aroma. According to some sources, the wild fennel fruit (Foeniculum vulgare Mill., subsp. piperitum (Ucria) Cout.) has a distinct bitter aftertaste and is primarily used in cosmetics.
Who should not take fennel seeds? / Does fennel have side effects?
Before drinking fennel tea, consult your doctor if you have any of the following conditions:
During pregnancy and breast-feeding, people with hormone-sensitive conditions, and bleeding disorders.
Can I eat fennel seeds daily? / How much fennel seeds should I eat daily?
- Yes. For preparing an infusion, 5-7 grams of fennel seed are recommended daily. Begin with lower doses to see how your body reacts.
- The maximum duration of administration for essential oils is two weeks.
Is fennel seeds good for gastric? / Is fennel good for upset stomach?
Anethole, Fenchone and Estragole in fennel seed have anti-spasmodic and anti-inflammatory properties that calm gastric and intestinal muscles.
Do fennel seeds increase stomach acid?
Animal studies have shown that fennel aqueous extracts (such as fennel infusion) can increased gastric acid secretion.
How do you consume fennel seeds?
- For relieving cough: pour a teaspoon of crushed fennel seeds (or a cumin tea bag) into a cup of boiling water, let it steep for 10 minutes, strain, and add honey. Enjoy your cumin seed tea!
- For relieving flatulence (as a carminative): pour a teaspoon of crushed fennel seeds (or a cumin tea bag) into a cup of boiling water, let it steep for 10 minutes, and strain. Drink after a meal!
* Crushed or ground the seeds (Saunf) for teas and tea-like recipes.
Can I eat fennel seeds raw?
Yes. Simply, you can chew the seeds (Saunf) after a meal to help combat bad breath, improve digestion, and prevent gas.
Do not chew more than one teaspoon of Saunf!
Is eating fennel seeds good for skin?
Studies have shown that applying fennel seed extract to the skin is beneficial. Base of these research, formulations containing fennel extract shown following effects:
1. considerable impacts on skin hydration and transepidermal water loss (TEWL) and probable anti-aging benefits.
2. a reduction in skin melanin (as a skin whitening agent), sebum content, and erythaema.
3. treatment of acne.
What does fennel seeds do to the female body?
According to a study on female mice, the seeds showed a hyperplasia effect. It means the seeds can increase the growth and development of the mammary gland, milk composition during pregnancy and milk secretion in lactating animals.
Do fennel seeds help in periods?
Fennel (Foeniculum vulgare) is recommended for starting menstruation and pain alleviation in traditional Persian medical texts. Additionally, recent studies have shown that Foeniculum vulgare can treat primary dysmenorrhea with only a few temporary side effects.
Is fennel good for men?
Although fennel herb has several medicinal advantages, a 2019 study on male rats suggests it also negatively affects sperm count and the male sex hormone. So, men should reduce fennel use, especially fennel oil.
Is fennel beneficial for liver and kidney detoxification?
Researchers have studied fennel for its potential benefits in detoxifying the liver and kidneys. Elevated levels of liver enzymes such as AST and ALT are common in cases of liver damage, while increased blood creatinine levels are common in cases of kidney damage. In 2017, a study found that fennel aqueous extract could effectively decrease the levels of the liver enzymes AST and ALT while also lowering blood creatinine levels. Furthermore, the study proposed that the fennel extract could potentially protect against infertility resulting from exposure to environmental toxins, such as heavy metals, and could potentially enhance fertility.
