© Wouter Hagens · Public domain · Commons
Tropaeolum majus
CautionGroße Kapuzinerkresse · (Tropaeolum majus)
Nasturtium family (Tropaeolaceae)
Description
Its fiery, peppery taste makes this member of the nasturtium family a popular edible flower in salads – but there's more behind the bite: the glucosinolate glucotropaeolin is converted in the body into benzyl isothiocyanate (BITC), which reaches effective concentrations in the urine after ingestion and inhibits uropathogenic bacteria there. As an infusion of leaves and flowers, the plant is therefore traditionally drunk for urinary tract infections, often combined with horseradish – such a combination has shown effectiveness comparable to other phytopharmaceuticals for acute respiratory infections in clinical observational studies too. Fresh leaves are also rich in vitamin C and the carotenoids lutein and zeaxanthin, and folk medicine applies crushed leaves as a poultice on minor wounds and insect stings, where BITC acts locally antimicrobial. At high doses the compound can irritate the stomach lining and kidneys, so concentrated preparations should be avoided in inflammatory kidney disease; regular high consumption also calls for attention to vitamin K content in people on blood-thinning medication.
Infusion of fresh or dried leaves and flowers for urinary tract infections. Benzyl isothiocyanate (BITC) derived from glucotropaeolin reaches therapeutically relevant concentrations in urine after oral intake and inhibits uropathogenic bacteria there.
Preparation & dosage
Pour 200 ml of boiling water over 2–3 g of dried leaves/flowers, steep covered for 10 minutes, strain. Drink 3 times daily.
- Dry amount
- 2–3 g
- Doses per day
- 3×
- Max duration
- 2 weeks
Tea from nasturtium herb (often combined with horseradish as in Angocin Anti-Infekt N) for acute respiratory tract infections. A clinical observational study shows effectiveness comparable to other phytopharmaceuticals for acute upper respiratory tract infections.
Preparation & dosage
Steep 2–4 g dried herb in 250 ml hot water for 10 minutes, strain.
- Dry amount
- 2–4 g
- Doses per day
- 3×
Sources: [2]
Ethanolic tincture of fresh herb as a concentrated BITC source. Used in folk medicine for recurrent urinary tract infections. Volatile BITC is less stable in aqueous tea, so a tincture provides more consistent dosing.
Preparation & dosage
Fresh leaves and flowers used as salad ingredient or garnish. Rich in vitamin C (approx. 130 mg/100 g), lutein, zeaxanthin, and glucotropaeolin. Plant source of antimicrobial sulfur compounds with a pleasantly spicy flavour.
Crushed fresh leaves applied as a poultice on minor wounds, skin blemishes, and insect stings. Local BITC release has antimicrobial and mildly anti-inflammatory effects. Folk medicinal use in Central Europe and South America.
Oil macerate from flowers and leaves as a base for salves for skin problems. Traditionally used for acne, small abscesses, and poorly healing wounds.
Sources: [8]
High doses of fresh herb or concentrated extracts may cause gastric mucosal irritation. BITC is potentially irritating to kidneys and mucous membranes in large amounts — do not exceed recommended daily doses. Allergies to Tropaeolaceae are rare but possible. ASPCA classification (accessed 2026-08-10): non-toxic to dogs and cats.
Avoid medicinal doses (concentrated extracts, tincture) during pregnancy — BITC has shown potential uterine effects in animal studies. Occasional culinary use (salad) is considered safe.
Insufficient data on BITC excretion into breast milk; avoid concentrated preparations as a precaution.
Concentrated preparations not recommended for children under 4 years. Occasional culinary use is safe.
Drug interactions
Antikoagulantien / Vitamin-K-Antagonisten
Nasturtium is rich in vitamin K; high regular consumption may affect INR in patients taking warfarin/acenocoumarol.
Contraindications
- Inflammatory kidney disease (acute glomerulonephritis, acute pyelonephritis) — BITC is irritating to renal parenchyma.
- Known hypersensitivity to nasturtium or other glucosinolate-containing plants (isothiocyanate allergy).
Harvested part: leaves and flowers
- Time of day:
- Harvest in the morning after dew has dried — essential compounds are most concentrated at this time.
- Drying:
- Dry gently at max. 35 °C or use fresh; BITC content decreases on drying due to myrosinase inactivation.
- Storage:
- 6 months — Store dried herb airtight in a dark glass container, cool and dry.
- Time of day:
- Morning when flowers are fully open; use flowers fresh for salads and tinctures.
- Drying:
- Flowers can be dried at 30–35 °C in a dehydrator or on paper; some colour loss is expected.
- Storage:
- 12 months — Candied or vinegar-pickled flowers keep for up to 12 months.
- GlucotropaeolinGlycosideContent: 0.5-1.5 %Aerial parts
Main glucosinolate of nasturtium; precursor of benzyl isothiocyanate (BITC), released via myrosinase-mediated hydrolysis.
- Benzyl-Isothiocyanat (BITC)OtherAerial parts
Main active metabolite after glucotropaeolin hydrolysis; antimicrobial, antifungal, and in studies also antitumoral and antimalarial. Reaches effective concentrations in urine.
- Vitamin C (Ascorbinsäure)VitaminContent: 0.1-0.15 %Leaf
Fresh leaves provide approx. 130 mg/100 g vitamin C; supports immune function.
- Quercetin-3-glucosidFlavonoidFlower
Flavonoid glycosides in flowers with antioxidant and mild anti-inflammatory properties.
- Lutein und ZeaxanthinOtherLeaf
Carotenoid pigments, especially in dark green leaves; protective for eye health.
- IsoquercitrinFlavonoidAerial parts
Another flavonoid glycoside; synergistic with BITC in antimicrobial activity.
- OxalsäureOtherLeaf
Present in moderate amounts; limit high consumption in oxalate-type kidney stone patients.
- [1]MonographEffectiveness of a Combination of Nasturtium Herb and Horseradish Root (Angocin® Anti-Infekt N) Compared to Antibiotics in Managing Acute and Recurrent Urinary Tract Infections: A Retrospective Real-world Cohort Study(accessed: 2026-05-24)
- [2]MonographAn Epidemiological Study on the Effectiveness of Nasturtium Herb and Horseradish Root (Angocin® Anti-Infekt N) as well as Other Phytopharmaceuticals, Synthetic Products, and Antibiotics on the Course of Acute Upper Respiratory Tract Infection (aURTI)(accessed: 2026-05-24)
- [3]MonographAntimicrobial activity of Angocin® Anti-Infekt N, a combination of nasturtium (Tropaeoli majoris herba) and horseradish (Armoraciae rusticanae radix)(accessed: 2026-05-24)
- [4]MonographIn Vitro and In Vivo Antitumor Activity of Benzyl Isothiocyanate: A Natural Product from Tropaeolum majus(accessed: 2026-05-24)
- [5]MonographDetermination of benzyl isothiocyanate metabolites in human plasma and urine by LC-ESI-MS/MS after ingestion of nasturtium (Tropaeolum majus L.)(accessed: 2026-05-24)
- [6]MonographMetabolism of Glucotropaeolin from Tropaeolum majus L. (Nasturtium) and the Bioavailability of Benzyl-Isothiocyanates in Growing Pigs(accessed: 2026-05-24)
- [7]MonographIsolation of a Microsomal Enzyme System Involved in Glucosinolate Biosynthesis from Seedlings of Tropaeolum majus L(accessed: 2026-05-24)
- [9]MonographASPCA Animal Poison Control — Nasturtium (Tropaeolum majus): Non-Toxic to Dogs, Non-Toxic to Cats, Non-Toxic to Horses(accessed: 2026-08-10)
- [8]WikipediaTropaeolum majus — Wikipedia(accessed: 2026-05-24)
Distribution in Europe
🪴 Grow at home
- ☀ Light
- full sun
- 💧 Water
- every few days
- 🌱 Soil
- Lean soil — otherwise only leaves, no flowers
- 🪴 Pot
- 25 cm
- ⭐ Difficulty
- ★☆☆ beginner
- 🐾 Pets
- non-toxic — verified against the ASPCA list
Tips:
- Don't fertilise — too rich = many leaves, few flowers.
- Flowers and leaves peppery-spicy in salad.
- Self-seeding — seeds are caper substitute.
Care tips are general indoor-gardening recommendations, not scientific sources.
🤝 Permaculture Partners
In your garden, this plant acts as:
✨ Best symbiotic partners
- 🌿 Garlic Classic companion-planting partner.
- 🌿 Apium graveolens Classic companion-planting partner.
- 🌿 Calendula officinalis Classic companion-planting partner.
- 🌿 Cucumber Nasturtium deters cucumber pests.
- 🌿 Cucurbita pepo Nasturtium deters aphids and squash beetles.
- 🌿 Zucchini Nasturtium deters squash beetles.
- 🌿 Eruca sativa Classic companion-planting partner.
- 🌿 Matricaria chamomilla Classic companion-planting partner.
- 🌿 Parsley Classic companion-planting partner.
- 🌿 Rosemary Classic companion-planting partner.
- 🌿 Tomato Nasturtium pulls aphids away from tomato (trap plant).
- 🌿 Tagetes patula Both deter soil pests and are edible.
- 🌿 Thymus vulgaris Classic companion-planting partner.
- 🌿 Maize Nasturtium as aphid trap protects maize.
⚠️ Better not planted together
- 🥬 Fennel Fennel is strongly allelopathic and inhibits nearly all neighbours.
📦 Part of these planting sets:
Source: Gertrud Franck, Gesunder Garten durch Mischkultur (1980, eigene Kuration) | Helga und Margarete Langerhorst, Mein gesunder Naturgarten (eigene Kuration) | Klassische Mischkultur-Tradition (Three Sisters, Bauernregel)