Know2eat

Fennel seed

Foeniculum vulgare

What fennel seed has been studied for

3 associations assessed — 1 with at least some human evidence behind it. Strongest first.

  • 1 Limited
  • 2 Insufficient
3 things to know first — allergies, interactions and intake limits

About fennel seed

The ridged fruit of the fennel plant, sweet and anise-scented from its anethole content, chewed as a mouth freshener in South Asia and brewed as a tea across the Mediterranean. The USDA entry is per 100 g of seed, while a teaspoon is about two grams.

Also known as fennel seed, saunf, sweet fennel, finocchio seed

Women's HealthGut & Digestive HealthMental Wellbeing

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how impressive the food is. How we rate evidence.

Menopausal symptoms

Women's Health
Limited evidence

Several small randomised trials of fennel soft capsules, typically 100 mg twice a day for eight to ten weeks, report reduced hot flushes and improved menopause symptom scores, and a meta-analysis pools them favourably. The pooled trials are small, nearly all from one region, and test a standardised extract rather than seed or tea.

Limited evidence. Early human work, or mostly lab and animal research.

2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Digestive comfort

Gut & Digestive Health
Insufficient evidence

Fennel appears in herbal combinations trialled for infant colic, bloating and dyspepsia, and some report symptom improvement. It is rarely tested alone, the trials are small, and the same preparations are the ones European regulators have flagged for use in young children.

Insufficient evidence. Not enough human research to say anything useful yet.

No source is attached to this association yet, so it is rated insufficient by default. It is listed because people commonly ask about it — not because there is evidence for it.

Mood

Mental Wellbeing
Insufficient evidence

A few of the menopause trials recorded mood and sleep scores as secondary outcomes with inconsistent results. That is not a body of evidence about fennel and mood, and no trial has set out to test it directly.

Insufficient evidence. Not enough human research to say anything useful yet.

2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Ask about Fennel seed

Ask about Fennel seed

Answers are written only from the entries on this page — the same nutrients, compounds, claims and citations you can read above. Nothing is added from outside the database, and every answer lists what it was built from.

AI explanations are not switched on for this site, so there is nothing to ask here. Everything above is read straight from the database and does not need them.

Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories345 kcal17%
Protein15.8 g32%
Total fat14.9 g19%
Carbohydrate52.3 g19%
Fibre39.8 g142%
Water8.81 g—
Fats
Saturated fat0.48 g2%
Monounsaturated fat9.91 g—
Polyunsaturated fat1.69 g—
Cholesterol0 mg0%
Linoleic acid (omega-6)1.69 g—
Vitamins
Vitamin A7 µg1%
Vitamin C21 mg23%
Vitamin D0 µg0%
Thiamin (B1)0.408 mg34%
Riboflavin (B2)0.353 mg27%
Niacin (B3)6.05 mg38%
Vitamin B60.47 mg28%
Vitamin B120 µg0%
Minerals
Calcium1196 mg92%
Iron18.5 mg103%
Magnesium385 mg92%
Phosphorus487 mg39%
Potassium1694 mg36%
Sodium88 mg4%
Zinc3.7 mg34%
Copper1.07 mg119%
Manganese6.53 mg284%
Other measured compounds
Ash8.22 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Spices, fennel seed (USDA FoodData Central, FDC ID 171323).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

  • brewedChanges volatile oil extraction

    Crushing the seed before steeping releases considerably more anethole into a tea than leaving it whole, which also means a stronger and less predictable dose of the same compounds the safety advice concerns.

  • roastedChanges aroma compounds

    Toasting mellows the sharp anise note and develops sweetness. It is a flavour change with no demonstrated nutritional consequence.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Worth knowing

    European regulators advise against fennel preparations in young children

    Fennel contains estragole, which is genotoxic and carcinogenic in rodents at high doses. The European Medicines Agency concluded that fennel tea and fennel preparations should not be used in children under four, and that use in older children and in pregnancy and breastfeeding is not recommended, precisely because the estragole exposure cannot be characterised.

  • Worth knowing

    Oestrogen-like activity at extract doses

    Anethole shows weak oestrogenic activity, which is why fennel capsules are trialled for menopausal symptoms. For the same reason, concentrated fennel extracts are usually discussed with a clinician by anyone with an oestrogen-sensitive condition, and avoided in pregnancy.

  • Allergy

    Carrot-family allergy and cross-reactivity

    Fennel allergy is documented, including anaphylaxis, and travels with sensitivity to celery, carrot, anise, coriander and mugwort pollen.