Nasturtium (Tropaeolum majus)

Nasturtium (Tropaeolum majus) is a flowering plant rich in glucosinolates — particularly glucotropaeolin — which are hydrolyzed to benzyl isothiocyanate (BITC), a compound with demonstrated antimicrobial, antioxidant, and antiproliferative activity. Its high phenolic content, including flavonoids and hydroxycinnamic acids, further contributes to its broad biological effects observed in preliminary research.

Origin & History

Nasturtium (Tropaeolum majus) is an edible plant native to South America, recognized for its functional food potential [1, 5]. Traditionally cultivated as an ornamental flower, its bioactive compounds like glucosinolates and phenolics are now concentrated for nutraceutical use through extraction methods employing generally recognized as safe (GRAS) solvents [1].

Historical & Cultural Context

Nasturtium has a long history in traditional medicine, where it was used as an antiscorbutic (vitamin C source), antimicrobial, and general tonic [2]. It was employed for conditions ranging from the common cold to sclerosis, though the specific traditional systems are not detailed in the provided research [2].

Health Benefits

["\u2022 May possess antiproliferative properties, based on preliminary in vitro evidence where its essential oil demonstrated activity (IC\u2085\u2080<5 \u00b5g/mL) against three human cancer cell lines [3].", "\u2022 Provides high antioxidant capacity, attributed to its rich phenolic content, including flavonoids and anthocyanins. In vitro analysis showed red flowers possess the highest radical-scavenging activity [4].", "\u2022 Exhibits potential antibacterial activity, as documented in early studies on nasturtium herb juice; however, specific bacterial targets and outcomes were not detailed in the available research [2].", "\u2022 Serves as a natural source of benzyl isothiocyanate (BITC), a bioactive compound identified in lab studies as a key driver of its potential biological effects [2, 3].", "\u2022 Contains a variety of nutrients, including B vitamins, minerals like potassium and iron, and carotenoids, as noted in analyses of the plant's traditional use profile [2]."]

How It Works

Glucotropaeolin, nasturtium's primary glucosinolate, is hydrolyzed by the enzyme myrosinase upon plant tissue damage to yield benzyl isothiocyanate (BITC), which disrupts microbial cell membranes and inhibits bacterial efflux pumps. BITC also modulates apoptotic pathways in cancer cells, likely through caspase activation and inhibition of the NF-κB signaling cascade, contributing to the antiproliferative IC₅₀ values below 5 µg/mL seen in vitro. Additionally, nasturtium's flavonoids — including quercetin and kaempferol glycosides — scavenge reactive oxygen species (ROS) and inhibit lipid peroxidation by donating hydrogen atoms to free radicals.

Scientific Research

The available research dossier contains no human clinical trials, randomized controlled trials (RCTs), or meta-analyses with PMIDs. The current scientific evidence is limited to in vitro (cell-based) and chemical characterization studies, which have not yet been validated in human subjects [2, 3].

Clinical Summary

Most evidence for nasturtium's benefits comes from in vitro and animal studies rather than controlled human clinical trials, limiting the strength of conclusions. In vitro studies have demonstrated antiproliferative activity of nasturtium essential oil (IC₅₀ <5 µg/mL) against three human cancer cell lines and strong antioxidant capacity assessed via DPPH and FRAP assays. Antimicrobial studies show BITC and nasturtium extracts inhibit gram-positive and gram-negative bacteria, including some antibiotic-resistant strains, though human pharmacokinetic and efficacy data remain scarce. The overall evidence is preliminary and promising, but randomized controlled trials in humans are needed before therapeutic claims can be substantiated.

Nutritional Profile

Nasturtium (Tropaeolum majus) leaves and flowers are nutrient-dense edible botanicals. Macronutrient composition per 100g fresh weight is modest in calories (~30-40 kcal), with low protein (~2-3g), minimal fat (~0.5g), and low carbohydrates (~5-6g), with dietary fiber estimated at ~1-2g. Micronutrient profile is notable for Vitamin C (ascorbic acid): leaves contain approximately 130mg/100g, significantly exceeding many common vegetables and rivaling citrus fruits; Vitamin A precursors (beta-carotene and other carotenoids) are present in moderate amounts, contributing to the orange-yellow pigmentation of flowers; Iron: approximately 1.5-2mg/100g in leaves; Potassium: estimated 300-400mg/100g; Calcium: approximately 100mg/100g; Magnesium: moderate amounts (~20-30mg/100g). Bioactive compounds are a primary point of interest: Glucosinolates, particularly glucotropaeolin (benzyl glucosinolate), are the signature phytochemicals, present at concentrations of 10-30 µmol/g dry weight in seeds, with lower concentrations in leaves; upon enzymatic hydrolysis by myrosinase (activated upon tissue damage or chewing), glucotropaeolin yields benzyl isothiocyanate (BITC), a bioactive compound with demonstrated antimicrobial and antiproliferative properties. Phenolic compounds include flavonoids (quercetin, kaempferol, and isorhamnetin glycosides) and anthocyanins (particularly in red/orange flowers, including pelargonidin and cyanidin derivatives), with total phenolic content reported at 15-50mg GAE/g dry weight depending on flower color, with red varieties exhibiting the highest concentrations. Carotenoids include lutein, zeaxanthin, and beta-carotene in leaves and flowers. Essential oil constituents include benzyl isothiocyanate as the dominant volatile compound. Bioavailability notes: Vitamin C bioavailability is considered good when consumed fresh and uncooked, as heat degrades ascorbic acid; glucosinolate hydrolysis to active BITC is dependent on intact myrosinase activity, which is reduced by cooking; fat-soluble carotenoids exhibit enhanced bioavailability when consumed with dietary fat; the phenolic compounds may have variable bioavailability depending on gut microbiome composition and food matrix interactions.

Preparation & Dosage

No clinically studied dosage ranges for human use have been established, as the research focuses on chemical characterization rather than human trials. Studied preparations have quantified bioactive compounds, such as 27.49 μmol/g of glucosinolates in fresh material, but these are not dosage recommendations [1]. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Broccoli Sprout Extract, Vitamin C, Green Tea Extract

Safety & Interactions

Nasturtium is generally regarded as safe when consumed in culinary amounts, but high-dose supplemental use may cause gastrointestinal irritation, including nausea and diarrhea, due to its pungent isothiocyanate content. Because glucosinolate metabolites can be goitrogenic at high chronic doses, individuals with thyroid disorders or those taking thyroid medications such as levothyroxine should exercise caution. Nasturtium may theoretically potentiate the effects of anticoagulant drugs like warfarin due to its vitamin K and flavonoid content, warranting monitoring of INR in affected patients. Pregnant and breastfeeding women should avoid supplemental doses beyond normal food use, as isothiocyanates have shown embryotoxic potential in animal models at elevated concentrations.