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Read one chapter at a timeBenzyl isothiocyanate shows antimicrobial (slows the growth of germs) activity in lab studies (respiratory and urinary pathogens).
Rich in vitamin C and lutein (a yellow pigment linked to eye health).
Traditional support for clearing damp lung congestion.
Known to botanists as Tropaeolum majus.
Sprawling annual with round, peltate green leaves and brilliant orange, yellow, or red trumpet-shaped flowers. Every aerial part — leaves, flowers, unripe seed pods — is edible and pungent.
Family: Tropaeolaceae.
Persian temperament: Hot & Dry (2nd degree). Grouped with cress and mustard as a pungent, fire-stirring herb for damp chests and cold digestion.
It was used: spring tonic to clear winter dampness from the chest and sinuses. Pungent salad green to stimulate sluggish digestion.
Topical (put on the skin) poultice (a soft paste held against the skin) for slow-healing skin and minor infections.
Mild diuretic (makes you pass more urine) for cold-type urinary irritation.
Lādan & Cress Spring Salad: fresh nasturtium leaves and flowers with watercress, olive oil, lemon, and a pinch of salt, which is a Persian spring tonic to clear winter dampness.
Other notable constituents
Minerals: Iron, Potassium
Antioxidants: Lutein, Anthocyanins (the natural colour pigments that make fruit red, purple or blue)
Notable: Benzyl isothiocyanate (mustard-oil glycosides)
From laboratory work, not from people taking it
Benzyl isothiocyanate from nasturtium shows antibacterial activity against common respiratory and urinary pathogens in laboratory work. Rated: early research.
What studies in people show
A herbal combination containing nasturtium and horseradish was as effective as antibiotics for acute urinary tract infection in a comparative trial.Moderate evidence
Toss 3–5 fresh leaves and a few petals into salads daily during spring/summer.
Pickle the unripe green seed pods in vinegar as 'poor man's capers'.
Cold infusion (a drink made by steeping the plant in hot water): 5 leaves bruised in a cup of cool water, steep 4 hours.
Fresh leaves and flowers in salads (3–5 leaves per serving).
In the kitchen: pickled flower buds as a Persian-style caper substitute, crushed-leaf poultice for slow-healing scratches (short contact only), and diluted fresh juice as a traditional scalp tonic for hair thinning.
Blood thinners — Nasturtium leaves are high in vitamin K, which works against warfarin (a blood-thinning medicine). Occasional salad leaves are fine; a daily habit needs mentioning to whoever monitors your levels. (moderate concern)
Diuretics — The plant has a mild diuretic effect of its own and can add to water tablets. (low concern)
Known kidney disease (the mustard oils are eliminated renally).
Pungent — start with small amounts.
Avoid large medicinal doses in pregnancy.
May irritate sensitive stomachs or kidneys at high doses.
Active stomach or duodenal ulcer.
General
Children under 4 years.
Pregnancy and breastfeeding
Salad amounts are fine. Concentrated nasturtium preparations, sold for urinary infections, have not been studied in pregnancy and should be left alone.
Children
Most children find the leaves too hot but like the flowers, which are milder and pretty on a plate. Avoid the pungent extracts entirely.
Older adults
A strong flavour that can bring back interest in food when taste has faded. Anyone with stomach ulcers or reflux (stomach acid rising into the throat) should keep the quantity small.
Cucumber
Cucumber cools what nasturtium heats. Half a leaf per person in a cucumber salad is plenty.
Yogurt
Chop leaves and flowers through thick yogurt. The fat takes the burn off.
Watercress
Both carry the same mustard-family bite. Together they make a salad that needs no dressing beyond oil.
Feta Cheese (Panir)
Salt and pepper heat work well together. This is the simplest way to serve the flowers.
Spring
Young leaves are at their best. Peppery but not harsh.
Summer
Flowers everywhere. Use them in salads and pickle the green seed pods.
Autumn
The plant turns leggy and the leaves get hot. Use less of them.
Winter
Nothing fresh outdoors. Pickled pods are the winter form.
End of the Nasturtium guide