Three fennel bulbs on a table

The health benefits of fennel

Low in calories but packed with potassium, discover the nutritional profile of this full-flavoured vegetable – plus how much counts towards your five-a-day.

What is fennel?

Fennel is a vegetable that is white-green in colour, and bulb-like in its shape with green stems and fronds that protrude slightly from its top. Varieties such as the Florence or Finocchio fennel are treated as a vegetable, but you can also buy fennel as a herb which has a fine foliage resembling dill.


Fennel has a strong, aniseed flavour. The whole bulb and stems can be eaten raw or cooked, making it quite versatile.

Nutritional profile of fennel

Fennel is largely water, around 94% per 100g, which also makes it is low in protein, fat and carbs with just 0.9g protein, 0.2g fat and 1.8g carbohydrates per 100g. The same serving size provides just 12 calories.

However, fennel has plenty of micronutrients including potassium which we need to support heart health. Just one 100g serving of fennel provides over 10% of the recommended daily allowance of potassium for adults. Fennel also contains a little calcium and iron.

Fennel is also quite a good source of folate, the naturally occurring form of folic acid, which is needed for healthy red blood cell formation as well as being important in pregnancy. A 100g serving of fennel provides around 20% of the recommended daily allowance for adults, or 10% of your intake if you’re pregnant or trying to conceive.

Fennel also contains a little beta-carotene which is converted to vitamin A when eaten. This is needed to support the immune system function and helps to keep the skin and eyes healthy.

Does fennel count as one of your five-a-day?

An 80g serving of fennel counts as one of your five-a-day, which is approximately a quarter of a large fennel bulb.

Discover more in our five-a-day infographic.

Can you be allergic to fennel?

Yes, although it is quite rare. People who have allergies to celery and carrot are more likely to be allergic to fennel.

A mild reaction may include symptoms such as itching mouth or tongue, sneezing or a runny nose. If you experience these symptoms, speak to your GP. If a more serious allergic reaction occurs, call for an ambulance immediately.

Visit the NHS website to read more about allergies.

How to buy the best fennel

Despite being available for most of the year, fennel is a seasonal summer vegetable in the UK and so is at its best during the summer months. Look for a bulb that’s unblemished and feels quite heavy for its size. The end of the stalk and any fronds should also look fresh and not dry, wilted or damaged.

Healthy fennel recipes

Baked salmon with fennel & tomatoes
Cucumber & fennel salad
Prawn, fennel & rocket risotto
Peppery fennel & carrot salad
Teriyaki steak with fennel slaw
Roasted fennel with tomatoes, olives & potatoes
Shaved fennel, courgette & orange salad
Whole stuffed roast fish with fennel

Now read

The health benefits of cumin
The health benefits of garlic
The health benefits of kimchi
The health benefits of turmeric

This page was published on 2nd March 2020.

Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Nutrition and Lifestyle Medicine (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at


All health content on is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.