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Nutrition and daily life

Fennel: a light aroma and comfort for the gut

Fennel seeds have a sweet aniseed aroma and are traditionally used for bloating. The bulb is cooked as a vegetable. This section covers fennel’s limits and cautions.

Last updated: ~1 min read
Fennel seeds in a brass dish, a fresh bulb and an infusion.
Figure 1.Fennel: seeds and bulb.

01Short answer

Fennel seed infusion and cooked fennel bulb are generally safe in ordinary amounts. Some people feel relief from bloating, but evidence is limited. Fennel contains oestrogen-like compounds; with hormone-sensitive tumours or hormone treatment, talk to your doctor. The essential oil is not for drinking. People allergic to celery or carrot may react.

02Simple explanation

Fennel has an aniseed aroma.

Traditional for bloating.

It has oestrogen-like compounds.

Essential oil: not for drinking.

03Scientific explanation

Studies: fennel’s anethole may have weak oestrogen-like effects; the essential oil is harmful at high doses.

NCI: there is no evidence that herbal infusions treat leukemia.

MSK: herbal products can affect how the liver breaks down medicines, so tell your oncologist.

04What happens in the body?

Seed infusion

Lightly crush a teaspoon of seeds, pour on boiling water and steep covered for 5–10 minutes.

Fennel seeds in a stone mortar.
Figure 2.Lightly crush the seeds.

As a vegetable

Braise or roast the fennel bulb; during neutropenia do not eat it raw in salads.

Golden roasted fennel slices on a tray.
Figure 3.Roasted fennel — Fennel: a light aroma and comfort for the gut

Safe brewing

Sealed bag, freshly boiled water, 5 minutes covered, drink hot. Do not drink an infusion that has stood for hours.

With medicines

1–2 cups of a mild infusion a day usually cause no problems; capsules and extracts only with your doctor.

05Brewing: four steps

Sealed bag, swap market herbs, boiling water, drink hot.

Sealed bag — Factory-made.1Sealed bagFactory-made.
Not loose — A bag instead.2Not looseA bag instead.
Boiling water — Covered.3Boiling waterCovered.
Drink soon — Do not keep.4Drink soonDo not keep.
ComfortA warm drink.
FluidsThrough the day.
SafetyBoiling water.

06Key points at a glance

TopicIn brief
Seed infusionLightly crush a teaspoon of seeds, pour on boiling water and steep covered for 5–10 minutes.
As a vegetableBraise or roast the fennel bulb; during neutropenia do not eat it raw in salads.
Safe brewingSealed bag, freshly boiled water, 5 minutes covered, drink hot. Do not drink an infusion that has stood for hours.
With medicines1–2 cups of a mild infusion a day usually cause no problems; capsules and extracts only with your doctor.

07Key terms

Anethole
The compound that gives fennel its aniseed aroma.
Phytoestrogen
A plant compound similar to oestrogen.
Infusion
A herb steeped in boiling water.
Extract
A concentrated plant substance.
Neutropenia
Low neutrophils.

08Key points

  • Fennel is a gentle aroma.
  • On hormone treatment, ask first.
  • Cook the bulb.
  • Sealed bag and boiling water.
  • Capsules only with your doctor.

09Frequently asked questions

Does it help bloating?

Some feel better; with severe pain or bloating, tell your doctor.

Can I drink it daily?

Usually 1–2 cups, yes.

Does this infusion treat leukemia?

No. It is a warm, pleasant drink, not a treatment.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Does it help bloating?

  2. Can I drink it daily?

  3. Does this infusion treat leukemia?

My questions

12Sources

  1. National Center for Complementary and Integrative Health (NIH). Herbs at a Glance
  2. Memorial Sloan Kettering Cancer Center. About Herbs, Botanicals & Other Products
  3. Leukemia & Lymphoma Society. Diet Guidelines for Immunosuppressed Patients
  4. National Cancer Institute. Complementary and Alternative Medicine
  5. MedlinePlus. Herbal Medicine
  6. MedlinePlus. Caffeine
  7. National Cancer Institute. Diet and Cancer Risk
  8. National Center for Complementary and Integrative Health (NIH). Chamomile
  9. National Center for Complementary and Integrative Health (NIH). Peppermint Oil
  10. National Center for Complementary and Integrative Health (NIH). Cinnamon
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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