Leek health benefits: broth, syrup and cautions

Updated on 21 September 2026Published on 16 April 2018

Leek is the mildest of the onion family, and one of the few vegetables that sits in the kitchen and the herbal cupboard at the same time. This page looks at what leek actually contains, what folk tradition and naturopathy have long credited it with, and how to turn it into broth, syrup, poultice or hair rinse — plus who should go carefully.

Leek at a glance
Item	Detail
Botanical name	Allium porrum
Family	Amaryllidaceae (formerly Alliaceae), the onion family
Part used	White stem, green leaves, cooking water
Forms of use	Broth, soup, strong decoction, honey syrup, poultice, juice lotion, hair rinse
Harvest season	Early autumn through to late winter, depending on variety
Taste	Sweet, mild, faintly sulphurous; silky when cooked slowly, sharper raw

Leek health benefits — *White stem and green leaves are both used in herbal preparations*

What it is credited with

Water balance — leek broth has an old reputation as a diuretic drink, and naturopathy still suggests it as a light, warming way to encourage urine flow.
Comfortable digestion — thanks to its fibre, herbalists traditionally recommend cooked leek and its broth to people whose bowels feel sluggish.
Throat and chest — in traditional herbalism, leek-and-honey syrup was the household remedy for a hoarse voice, a tickly cough or a raw throat.
Drawing poultices — our grandmothers layered hot boiled leek leaves on boils and on sore, swollen joints, for a soothing and “ripening” effect; the same poultice was laid on the lower abdomen to encourage urine flow.
Skin — leek juice lotions have a folk reputation for freshening the complexion and calming small blemishes, and for taking the itch out of insect bites.
Refreshment — the Hebrews valued leek above all for what they called its refreshing, cooling qualities, and that framing survives in naturopathic food traditions.
Hair — a leek decoction is said in old cosmetic lore to bring out the shine in auburn hair.

How to use it

Leek broth, the classic

Take 2 or 3 leeks, whites and green tops, wash them very well (grit hides between the layers) and slice into rounds.
Drop them into 1 litre (about 4 cups) of cold unsalted water, bring to a simmer and cook gently for 20 to 30 minutes.
Strain and drink the liquid warm, as you would a herbal tea — a cup in the morning and a cup in the evening is the usual household habit, over a few days rather than for weeks.
Taste: faintly sweet and clean. A squeeze of lemon or a sprig of thyme lifts it considerably.
Eat the cooked leeks too, with a little olive oil; that is where the fibre is.

Leek and honey syrup

Make a strong decoction: chopped leek, just enough water to cover, simmered until the liquid has reduced by half.
Strain, weigh the liquid, and stir in the same weight of honey while still warm.
Warm gently until smooth, bottle in a clean jar, and keep in the fridge for up to two weeks.
Traditional use: a teaspoonful, taken slowly, when the voice is tired or the throat feels scratchy.
Taste: sweet and savoury at once, closer to onion syrup than to fruit syrup.

Poultice

Boil whole green leaves for a few minutes until soft and floppy.
Let them cool to comfortably warm — never hot enough to sting — and lay them flat on the skin.
Hold in place with a cloth for 15 to 20 minutes, then discard the leaves.

Juice lotion and hair rinse

Blend raw white stems, strain through muslin, dilute the juice with an equal amount of water, and dab on with cotton wool.
For hair, use a cooled, well-strained decoction as a final rinse after shampooing, then rinse again with plain water if you dislike the smell.

In the kitchen

Steamed or boiled, dressed warm with vinaigrette.
Softened slowly in butter or oil as a side for fish and crab.
Pickled, for a bittersweet condiment.
Young slim leeks sliced thinly and raw into mixed salads — surprisingly good.
Baked into a leek and ham quiche or a leek pie.

Forms of leek preparation compared
Form	How it is made	Traditionally used for
Broth	Sliced leek simmered 20–30 min in unsalted water, strained	Drunk warm as a diuretic-style drink
Syrup	Strong decoction reduced by half, mixed with an equal weight of honey	Taken by the spoonful for a hoarse, scratchy throat
Poultice	Green leaves boiled soft, applied warm under a cloth	Soothing, “ripening” applications to boils and sore joints
Juice lotion	Raw whites blended, strained, diluted with water	Freshening the complexion, calming bites and blemishes
Hair rinse	Cooled strained decoction poured over washed hair	Bringing shine to auburn hair

Cautions

In the garden: to avoid bolting, remember to water your leek regularly and keep the soil free of weeds.
Anyone allergic or sensitive to onion, garlic or other alliums should avoid leek in all forms, internal and external.
Leek is high in fermentable fibre. Sensitive or irritable bowels may react with wind and bloating, especially to large amounts of broth.
Do not use leek broth or syrup as a home diuretic if you have kidney or heart conditions, or if you take diuretic, blood-pressure or blood-thinning medication. Speak to a healthcare professional first.
Pregnancy and breastfeeding: leek as a food is ordinary fare, but concentrated broths, syrups and juice cures are not the moment for self-experimenting.
Children: leek in cooking is fine; honey-based syrups must never be given to infants under one year, and herbal cures for children should go past a health professional.
Skin and poultices: patch-test diluted juice on the forearm first, keep it away from eyes, mucous membranes and broken skin, and never apply leaves hot enough to burn.
Any sore throat, cough, swelling or skin problem that lasts, worsens or comes with fever needs a doctor, not a poultice.

Frequently Asked Questions

The one thing to remember: simmer two or three whole washed leeks in a litre of unsalted water for 20 to 30 minutes, then drink the strained broth warm and eat the leeks too.

Which part of the leek should I use?

Both parts have a job. The white stem is the sweeter, milder part for eating, juicing and raw salads. The dark green tops, often thrown away, are the traditional material for broths, strong decoctions, hair rinses and poultices.

How long can I drink leek broth for?

Household tradition treats it as a short course rather than a permanent habit — a cup morning and evening for a few days. If you take diuretic or blood-pressure medication, or have kidney or heart conditions, check with a healthcare professional before drinking it as a cure rather than as soup.

Does leek syrup taste unpleasant?

It is sweet and savoury at the same time, much closer to onion syrup than to a fruit syrup. Made with a good honey and taken by the teaspoon it goes down easily enough. Remember that honey preparations are never given to babies under one year old.

Can I eat leek raw?

Yes, if it is young and slim. Slice it very thinly into mixed salads for a fresh, mildly pungent bite. Older, thicker leeks are tougher and much sharper raw, so they are better softened slowly in butter or oil.

When is leek harvested?

Depending on the variety, leeks are lifted from early autumn right through to late winter, which is exactly when broths and syrups are most welcome. Winter-hardy types can be left in the ground and pulled as needed.

This information is provided for general interest and reflects the traditional use of plants. It is not a substitute for medical advice. If you are on medication, pregnant, or in any doubt, ask a healthcare professional.