Fennel is part of the same plant family as dill, angelica, parsley, carrot or hemlock, which is characterized by its umbel inflorescence (hence the ancient umbelliferous name); the flowers (usually small) are borne by short stems that all emerge from the same point on the main stem.
Foeniculum vulgare comprises several subspecies or varieties.
This plant native to the Middle East and warm regions of Europe is known, used and cultivated for a long time; varieties have been selected which have naturally crossed again so that they are not easy to classify.
Botanists and pharmacologists agree tentatively to differentiate:
- F. vulgare var. vulgare or bitter fennel,
- F. vulgare var. dulce or sweet fennel with a more pronounced bulb.
But some describe F. vulgare var. piperitum as the bitter and wild form; finally the cultivated variety or Florence fennel, selected by the Romans for its fleshy and edible "bulb" is var. azoricum.
Wild fennel, which is found throughout the temperate and warm part of Europe along roadsides, roads, in embankments, uncultivated and rocky areas, wastelands, quite often near the sea is, most often, perennial plant (sometimes biennial), with a fusiform root elongated the size of a finger, a rounded, green, erect (0.5 to 2 m), supple and ramous stem, which bears small yellow flowers pruning during the summer, the fruits (achenes) become brown when ripe.
The alternate leaves, green to blue-green, have a very sheathing petiole that surrounds the stem, they are finely divided into a large number of segments.
The whole plant, when crushed, and the fruits, give off a pleasant aniseed odor, sometimes a little camphorous in the bitter varieties.
Fennel is easy to grow, it is spread all over the world even in cold countries where it is annual.
CHEMICAL COMPOSITION AND PROPERTIES
FENNEL ESSENTIAL OIL
All parts of the fennel contain essential oil, but the composition varies according to the organs of the plant (seeds, aerial parts and root) and depending on the varieties:
- sweet fennel (Foeniculum vulgare variety dulce),
- wild or bitter fennel (Foeniculum vulgare variety piperitum or vulgare),
- edible fennel (Foeniculum vulgare azoricum variety).
The fruits (or seeds or seeds) essential oil is used in aromatherapy.
The DRY FRUITS contain 2 to 6% of essential oil whose average composition varies with the varieties and the conditions of cultivation, we give below average examples:
- Essential oil of fruit (seed) of SWEET FENNEL :
80% anethole (trans = E-anethole), 5 to 10% estragole (methyl-chavicol), less than 5% alpha pinene, less than 2% (+) - fenchone.
- Essential oil of fruit (seed) of BITTER FENNEL :
It contains a lot more estragole and fenchone.
50 to 80% estragole, 5 to 20% fenchone, about 20% limonene, 5% anethole, less than 5% alpha pinene.
- Essential oil of fruit (seed) of EDIBLE FENNEL:
60% anethole, 10 to 15% limonene, about 10% estragole, and 5 to 10% fenchone.
The essential oil of the aerial parts (stems and leaves) has a composition completely different from that of its fruits, for example for the bitter fennel (foeniculum vugare var piperitum) it is dominated by the anethole (30 to 40%), the alpha pinene (15 to 20%) and limonene (10 to 15%).
ANETHOLE ESTRAGOLE FENCHONE
The main components of essential oils of fennel are anethole, estragole and fenchone
Anethole (trans = E-anethole) whose aniseed smell is typical of fennel (or pastis!) Is known for its properties:
- APRITIVE (gives appetite), eupeptic (promotes digestion) and slightly stimulating (increases tone and awakening).
- CARMINATIVE (promotes the elimination of intestinal gas).
- BACTERICIDAL and antifungal.
- But anethole is also TOXIC beyond a certain dose: the LD 50 per os in the rat of E-anethole is 3.2 g per kg but its chemical isomer Cis or Z-anethole is much more dangerous LD 50 per os in the mouse is 0.24 g per kg.
The daily man acceptable amount of this cis isomer is 2.5 mg per kg per day.
Anethole is potentialy NEUROTOXIC and can thus cause CONVULSIONS, in general without sequelae when they are of little intens
Estragole or methyl-chavicol is CARCINOGENIC in rats and mice, particularly for the liver, but at high doses and isolated from the other components of the essential oil.
Fenchone is an insect REPELLENT, it removes flying insects especially mosquitoes: experiments on Aedes aegyptii (agent transmitting arboviruses) and other common rice mosquitoes (experiments in South Korea).
Fenchone is also insecticide and insect repellent especially against house dust mites responsible for respiratory allergies and asthma.
It is 6 to 10 times more active than thymol and 30 to 40 times more than estragole against these insects.
MEDICINAL PROPERTIES OF FENNEL ESSENTIAL OILS
Essential oils of different varieties of fennel:
- are EUPEPTIC AND CARMINATIVE , they promote digestion, this is their main indication.
- are also ANTI BACTERIAL AND ANTIFUNGAL (but much less than those with thymol or eugenol)
The essential oil of BITTER FENNEL has traditional uses:
- it interacts with female sex hormones (or it is mimetic of these hormones) and can thus promote the "rise of milk" (galactologue) and perhaps have an estrogenic effect (feminizing) but this remains to be proven.
Tests in Iran, however, have shown that a cream with 2% ethanol extract of fennel fruit slightly decreased the diameter of the hairs in cases of primary hirsutism.
- Fennel essential oil is traditionally used to calm the colic of children and infants; it has both a SPASMOLYTIC and regulating effect on intestinal motility (example from a study in Russia in infants 2 to 12 weeks old, taking a little bit of emulsified bitter fennel fruit essential oil improves in 65 % of cases "colic" compared to 24% for placebo, without significant side effects.
But we must not forget that this essential oil irritates the nervous system and can cause convulsions in the young child ( personally I do not recommend it) .
- The essential oil of bitter fennel has traditional used outside of Europe:
- A hepatoprotective power (study in Turkey), but do not forget that estragole can induce liver tumors, this seems to me to be a bad indication.
- An anti-inflammatory and analgesic power (study in Iran on primary dysmenorrhea).
The essential oil of fennel that one breathes acts on the neurovegetative system, it seems to increase the activity of the sympathetic (increase of the arterial tension, the heart beat, the vigilance), it is an essential oil with a pleasant and slightly "tonic" smell.
OTHER MEDICINAL COMPONENTS OF FENNEL
The whole plant stem, root and seed contains:
- Organic acids and flavonoids scavengers of free radicals and therefore anti-oxidants and anti-inflammatories.
- Furanocoumarins (as in other APIACEAE) which may cause skin disorders by contact with the sap: a bullous dermatitis or secondary hyperpigmentation.
These skin disorders are aggravated in the sun (phototoxicity) and increased in a humid environment.
- The ethanolic root extract (alcoholic tincture at 15 °) is diuretic but much less its aqueous extract .
FENNEL IN FOOD
The fennel (leaf, bulb and fruit and same stalk) is a typical condiment of the "Mediterranean" cuisine, it goes perfectly with fish, some also use it in cold cuts.
It is an important source of trans-anethole widely used in the food industry, pastry and liquoristry (pastis).
FENNEL MEDICINAL PLANT
The fruit (or seed) of fennel and its essential oil (mainly sweet fennel essential oil with anethole with little fenchone and little estragole = methyl chavicol) are:
- CARMINATIVE AND EUPEPTIC : they are recommended in case of SLOW DIGESTION, lack of APPETITE, intestinal gas, FLATULENCE, AEROPHAGIA.
- REGULATORS OF INTESTINAL AND GASTRIC ACTIVITY : gastrointestinal functional disorders with cramps and "spasms". Spasmodic colitis with pseudo constipation or mucous colitis of IRRITABLE BOWEL SYNDROME.
- Also favor the expectoration of bronchial secretions: catarrhous bronchitis that follows seasonal viral infections, chronic bronchitis of the smoker.
EXAMPLES OF DOSAGE
Fruit INFUSION (seeds) :
2 teaspoons of seeds, if possible a bit crushed, in 1/2 liter of very hot water, infuse 10 to 15 minutes, filter: drink in the day, before the meal as an aperitif or after difficult digestion .
ESSENTIAL OIL of "sweet" fennel :
6 drops a day in 2 to 3 times (in honey for example or directly in the food if it is appropriate), limit to a week and avoid taking in the evening because it can delay sleep.
Do not use in children and pregnant or lactating women, in people with hormone-dependent cancer (such as breast cancer for example).
CRUSHED SEEDS POWDER at 1.5% HE :
1 to 2 g per day in capsule at a distance from meals.
ETHANOLIC TINCTURE OF SEEDS :
30 drops, 3 to 4 times a day without exceeding 150 drops a day, before the meal to give the appetite and after to facilitate the digestion.
No more than 2 weeks in a row.
Do not use in children and pregnant or breastfeeding women.
TOPICAL USE :
Plaster of crushed seeds, massage with HE, cream with HE, eye drops with infusion, are not recommended because of the risk of photosensitization.
FENNEL A COMMON DIGESTIVE PLANT WITH ANISE ODOR
Fennel, which aromatises Mediterranean cuisine, has fruits that promote appetite, help to digest, soothe digestive cramps and facilitate the expectoration of bronchial secretions.
The different varieties of fennel (bitter, sweet, edible) contain essential oils with aniseed odor but with very different chemical compositions.
In aromatherapy the essential oil of "sweet" fennel is preferably used.
Copyright 2019 : Dr Jean-Michel Hurtel