Fennel: nutrition facts and health benefits


Fennel is a perennial and Mediterranean aromatic plant. Its bulb is consumed as a vegetable; its branches are used as an aroma and its seeds as a condiment. Its aniseed flavor comes from a substance, anethole, also present in anise.

The history of fennel

Fennel “anise” or “dill” is often erroneously called. This confusion is found in many languages and results from the resemblance, both in form and by their uses, between these three plants of the family of Apiaceae. However, only fennel is used as a vegetable.

Originally from Southern Europe and Asia Minor, where it still grows wild on rocky, dry terrain, fennel has been consumed since the most remote times. Cultivated by the Egyptians, it was popular among the Greeks and Romans. The latter used it for its medicinal properties, especially as an antidote to the stings of scorpions as well as the bites of snakes and dogs. The rich symbolic surrounding this plant makes it possible to measure the importance it has covered over the centuries. Thus, in the ancient Phrygia, the followers of the worship of the Sabazios God were able to do so during the ritual ceremonies. According to Greek mythology, humans received the knowledge of Olympus in the form of a fiery coal placed in a fennel stalk. Finally, for the ancient Anglo-Saxon, it was one of the nine sacred herbs that could fight the nine possible causes of the disease.

However, the fennel bulb (which is not strictly speaking a bulb, but a bulge at the base of the stem) as people know it today does not exist in the wild. Rather, it results from a long selection process undertaken by the Italians, probably in Sicily, where it is found in many traditional dishes. Until recently, this subspecies (F. vulgare var. azoricum) was cultivated only in the Mediterranean basin. Because the plant was sensitive to photoperiod (daily duration of illumination or length of the day considered for its effects on the development of animal and plant organisms), it was easily seeded in the northern regions. Then, this situation changed in the 1970s, after researchers had selected varieties tolerant on the longest days of the Nordic summers. Since then, its culture has spread both in the United States and in northern Europe and in the United Kingdom. Italy remains the country where people consumes, produces and exports the most.

Health profile of fennel

Fennel is a vegetable with aniseed flavour, of which one eats mainly the base of the stem, called a bulb. An indispensable companion of fish and seafood, it is a source of vitamin C. It would be advantageous to consume more often its leaves which contain antioxidant substances.

Note: this article deals mainly with leaves and bulbs of fennel, although other parts of the plant (fruits, seeds, essential oil) have been investigated and contain some active compounds which could have beneficial health effects.

The benefits of fennel

Several prospective and epidemiological studies have shown high consumption of vegetables and fruit decreases the risk of cardiovascular diseases, certain cancers and other chronic diseases. The presence of antioxidant compounds in vegetables and fruits could play a role in these effects.

Bone health. A study showed fennel added to the feeding of rats decreased bone resorption (loss of bone substance). Some studies concluded the consumption of some fruits and vegetables had the same effect among animal and was associated with better bone density among humans. The direct effect of fennel consumption on bone health among humans has not yet been studied.

Hypertension. A study conducted in the animal showed that consumption of a fennel extract decreased the systolic blood pressure. The fennel extract appears to exert this hypotensive effect by increasing the excretion of water, sodium and potassium among animals. These promising results will have to be confirmed by clinical studies among humans before a clear conclusion about the effect of fennel on blood pressure can be issued. However, it is important to mention other studies have obtained contradictory results as reported in a literature review.

Studies among animals or in vitro have shown some compounds found in fennel can help prevent certain types of cancer, such as colon cancer. Some authors argue that fennel will reduce the risk of cancer through, among other things, its antioxydants effects. However, the usefulness of fennel extracts in the prevention of cancer must be confirmed among humans.

What does fennel contain?


Researchers have found a dozen antioxidant compounds, mainly flavonoids, in an extract of flowers, leaves and stems of fennel. According to another study, the extract of fennel leaves would have even an antioxidant activity greater than that of other aromatic herb extracts typically consumed in the Mediterranean diet (e.g. chicory, Poppy and Saunicorn). Although it is not known whether the fennel bulb also contains antioxidants, fennel leaves should be incorporated into our diet. Their antioxidant properties could protect the body cells from damage caused by free radicals. The latter are highly reactive molecules which would be involved in the development of cardiovascular diseases, certain cancers and other diseases related to aging.

Fennel would have an antioxidant power similar to other fine herbs such as laurel leaves, rosemary, basil, thyme and origano.

A recent study has shown fennel sprouts contain more antioxidant capacity than fennel leaves. Indeed, shoots would contain more phenolic compounds and flavonoids than fennel leaves. Although the fennel leaves hold antioxidant properties, they would contain a negligible amount of flavonoids, according to the same study.


Fennel contains polyacetylene, bioactive compounds that have demonstrated anti-inflammatory and antibacterial effects in addition to preventing the multiplication of in vitro cancer cells. However, the concentration of these compounds in fennel is minor compared to parsley and celery. The effects of polyacetylene among humans when consuming fennel are still to be demonstrated.


Fennel is an incriminating food in the oral allergy syndrome. This syndrome is an allergic reaction to certain proteins of a range of fruits, vegetables and nuts. It affects some people with environmental pollen allergies, specifically to birch pollen in the case of fennel. Thus, when some people allergic to pollen consume raw or cooked fennel, an immunological reaction may occur. These people have itching and burning sensations are confined to the mouth, lips and throat. Symptoms may appear and then disappear, usually a few minutes after consuming or touching the food. In some more severe cases an anaphylactic reaction may occur. In the absence of other symptoms, this reaction is not serious and the consumption of fennel does not have to be avoided systematically. If similar reactions occur at the time of fennel consumption, it is advisable to consult an allergist to determine the cause of the reactions to plant foods. The latter will be able to assess whether special precautions should be taken.

Choice and conservation


Fennel is usually found in the month of June until much of the winter. The bulb should be white or light green, firm, without yellowish or woody traces, and give off a pleasant smell of liquorices or anise. Preferably choose small bulbs, which are much tenderer than the big ones. The leaves, when they are present, should be well green and fresh.


Refrigerator. A few days in an airtight container. Consume it as quickly as possible, as it quickly loses its flavor.

Freezer. Mince and blanch for five minutes. Cool under cold water and drain thoroughly before freezing. Avoid too long freezing, which would cause it to lose its flavor.

Organic gardening

The culture of fennel requires a certain fingering, but the result is really worth it. The freshly harvested vegetable in the garden is much tastier than the one found in the trade.

  • You can sow it indoors early in the spring and put it back in the garden when the gels no longer threaten. Also, you can sow it in the middle of the summer to harvest it in the fall.
  • Choose a sunny and dry place. The soil should have been enriched the previous fall.
  • Ph: 6.5 to 7; Spacing between the plants: 30 cm.
  • Irrigation: Ensure that it receives water every week.
  • Cut the floral stems if the plant is looking to seed. When the bulb is roughly the size of an egg, butter the plant.

Note: it is preferable to devote to fennel a space of its own, as it inhibits the growth of many vegetable plants, especially bean, tomato and cauliflower. In addition, fennel and coriander inhibit each other.

Ecology and environment


Fennel was introduced into California as a condiment plant in the early days of colonization. It has become naturalized in the central and southern part of the state to the point of being considered a weed. It invades the wasteland, lands along roads or rivers and other uncultivated areas. It tends to occupy all the space at the expense of local species and it is difficult to eradicate it. Moreover, because of its strong aniseed smell, the livestock refuses to graze it so well it has no interest for the breeders.

People aimed at eradicating fennel and restoring the original wild flora have therefore been set up. However, entomologists are concerned about this decision, as some local insect species have become entirely dependent on it for survival. This is the case of Zelicaon, a butterfly belonging to the group of Swallow tails, whose larvae feed exclusively on them. Prior to the introduction of fennel, this species fed on angelica and pork fennel, two native plants of the same family that practically disappeared from the area due to the loss of their habitat. The question arises today is: should the flora of a region be restored to the disappearance of local animal species? Should we be willing to accept the irreversible changes in human activities, particularly in cases where wildlife seems to have adapted well?


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