Fennel is highly prized for its licorice-like flavor and its health benefits. It has been used in natural remedies since ancient times.
Originally cultivated in the Mediterranean, fennel is still used in many Greek and Italian dishes, but it is now used around the world, too.
Fennel has a pale bulb and long green stalks. It can be grown almost anywhere. All parts of the fennel plant, including the bulb, stalk, leaves, and seeds, are edible. They add flavor to other foods.
This article is part of a collection of MNT articles on the health benefits of popular foods.
Contents of this article:
Nutritional breakdown of fennel
Fennel provides fiber and nutrients.
According to the United States Department of Agriculture (USDA) National Nutrient Database one raw fennel bulb weighing 234 grams contains:
- 73 calories
- 0.47 grams of fat
- 2.9 grams of protein
- 17 grams of carbohydrate
- 7.3 grams of dietary fiber
- No cholesterol
A cup of fennel also provides:
- 360 micrograms (mg) of potassium
- 45 milligrams of sodium
- 838 international units (IU) of vitamin A
- 43 milligrams of calcium
- 10.4 milligrams of vitamin C
- 0.64 milligrams of iron
- 0.041 milligrams of vitamin B-6
- 15 milligrams of magnesium
Fennel also contains phosphorous, zinc, copper, manganese, selenium, niacin, pantothenic acid, folate, choline, beta-carotene, lutein, and zeaxanthin, vitamin E, and vitamin K.
In addition to all these nutrients, it provides high levels of dietary nitrates and is a natural source of estrogen.
Possible health benefits of fennel
The nutrients in fennel are linked to a range of health benefits.
Vitamin K is important for health, as it modifies of bone matrix proteins, improves calcium absorption, and may reduce the excretion of calcium in urine.
Maintaining a low sodium intake is essential for lowering blood pressure, but increasing potassium intake may be just as important because of its role in vasodilation, the dilation and contraction of blood vessels.
The minerals in fennel can help reduce blood pressure.
According to the National Health and Nutrition Examination Survey (NHANES), fewer than 2 percent of American adults meet the daily 4,700 mg recommendation for potassium.
Dietary nitrates present in fennel and other foods have vasodilatory and vasoprotective properties. Because of this, they helps to lower blood pressure and protect the heart.
One Swedish study found that blood pressure levels were lower after taking nitrate supplements that contained nitrate amounts equivalent to 150-250 grams of nitrate-rich vegetables, than after taking a placebo.
Fennel contains significant amounts of fiber. As fiber helps lower the total amount of cholesterol in the blood, it decreases the risk of heart disease.
Potassium appears to promote heart health. In one study, those who consumed 4,069 milligrams of potassium per day had a 49 percent lower risk of death from ischemic heart disease compared with those who consumed around 1,793 milligrams per day.
Vitamin B-6 and folate prevent the build-up of a compound called homocysteine. When excessive amounts of homocysteine accumulate in the body, it can damage blood vessels and lead to heart problems.
Selenium is a mineral that occurs in fennel, but not in most fruits and vegetables. It contributes to liver enzyme function and helps detoxify some cancer-causing compounds in the body. Selenium can also prevent inflammation and decrease tumor growth rates.
Fennel seeds provide flavor and nutrients.
Fiber intake from fruits and vegetables like fennel are associated with a lower risk of colorectal cancer.
Vitamin C, vitamin A, and beta-carotene function as powerful antioxidants that help protect cells against damage from free radicals.
Fennel contains folate, which plays a role in DNA synthesis and repair. This may help prevent cancer cells from forming because of mutations in the DNA.
The selenium found in fennel appears to stimulate production of killer T-cells. This suggests that it can improve the immune response to infection.
Choline is a very important and versatile nutrient in fennel that helps with sleep, muscle movement, learning, and memory.
Fennel is a source of vitamin B-6, which plays a vital role in energy metabolism by breaking down carbohydrates and proteins into glucose and amino acids. These smaller compounds are more easily utilized for energy within the body.
Digestion and regularity
Because of its fiber content, fennel helps to prevent constipation and promotes regularity for a healthy digestive tract.
Weight management and satiety
Dietary fiber is an important factor in weight management and loss by working as a "bulking agent" in the digestive system. These compounds increase satiety and reduce appetite, making an individual feel fuller for longer and so lowering overall calorie intake.
Increasing iron absorption
Iron deficiency is one of the most common nutrient deficiencies in developed countries and a leading cause of anemia. Pairing foods like fennel that are high in vitamin C with foods that are iron-rich maximizes the body's ability to absorb iron.
Estrogen occurs naturally in fennel. It is crucial in regulating the female reproductive cycle, and it can also affect fertility.
A mouse study conducted by The University of Texas Southwestern Medical Center found that estrogen also plays an important role in controlling factors that contribute to body weight, such as appetite and energy expenditure.
Some research has suggested that fennel extract may reduce the effects of premenstrual syndrome (PMS).
Raw fennel is an excellent source of vitamin C. Vitamin C is essential to collagen, the skin's support system. It works in our bodies as an antioxidant to help prevent damage caused by the sun, pollution, and smoke.
Vitamin C also promotes collagen's ability to smooth wrinkles and improve overall skin texture.
How to use fennel in the diet
Fennel has a crunchy texture and mildly sweet flavor, making it a pleasant addition to any dish, whether eaten raw or cooked. All parts of the fennel plant can be eaten, and the seeds are used as a condiment in many recipes.
Raw fennel gives a fresh taste to a salad.
When purchasing fennel, look for bulbs that are firm and white or pale green and avoid spotted or bruised ones. Stalks should be green and leaves should be straight and bundled together. A plant with flowering buds is overripe.
Fresh fennel will keep in the refrigerator crisper for about 4 days. It is best to eat fennel right after purchase because it loses flavor over time.
Dried fennel seeds can last for about 6 months in an airtight container, in a cool, dry area, such as a spice cabinet.
To prepare fennel, cut the stalks off the bulb at the base where they sprout and then slice the bulb vertically. The fennel leaves, stalks, and bulb can be prepared in a variety of ways:
- Use the stalks as a soup base or stock
- Sauté the leaves and stalks with onions for a quick and easy side
- Mix sliced fennel with a variety of your favorite fresh vegetables for a light, crisp salad
- Serve roasted fennel bulbs as an entrée
Potential health risks of fennel
Some spices, including coriander, fennel, and caraway, may cause severe allergic reactions in some individuals. Those who are allergic to these spices should avoid consuming them.
Beta-blockers, a type of medication most commonly prescribed for heart disease, can cause potassium levels to increase in the blood. High potassium foods such as fennel should be consumed in moderation when taking beta-blockers.
High levels of potassium in the body can pose a serious risk to those with kidney damage or kidneys that are not fully functional. Damaged kidneys may be unable to filter excess potassium from the blood, and this could be fatal.
It is important to remember that a single food cannot prevent disease and improve overall health, but an overall healthy diet can. A variety of fresh foods is the key to good health.