Wise Mind Herbs

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Nasturtium - Tropaeolum majus

Nasturtium (Tropaeolum majus L.) is an ornamental plant from the Tropaeolaceae family native to South America. It has been used in traditional medicine for centuries and has garnered scientific interest for its potential therapeutic properties. This review examines the evidence for nasturtium's health benefits based on peer-reviewed scientific literature.

Botanical Classification and Common Names

Tropaeolum majus L. is commonly known as garden nasturtium, Indian cress, monks cress, or kapuzinerkresse (German). It should not be confused with watercress (Nasturtium officinale), which belongs to the Brassicaceae family and despite sharing a common name is botanically distinct. Another potential confusion exists with Nasturtium microphyllum (one-row yellowcress), which is also distinct from garden nasturtium.

Bioactive Compounds

Nasturtium contains several bioactive compounds that contribute to its therapeutic properties. The most important compounds include glucosinolates (particularly glucotropaeolin), flavonoids, carotenoids, vitamin C, and minerals. When plant tissues are damaged, glucotropaeolin is hydrolyzed by the enzyme myrosinase to produce benzyl isothiocyanate (BITC), which is considered the primary bioactive constituent responsible for antimicrobial and anti-inflammatory effects.

Evidence-Based Health Benefits

• Antimicrobial Activity: Multiple in vitro studies have demonstrated significant antibacterial activity against respiratory and urinary tract pathogens, including Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The isothiocyanates from nasturtium appear to be responsible for these effects.
• Respiratory Tract Infections: Combined with horseradish extract, nasturtium has shown efficacy comparable to antibiotics in treating acute sinusitis and bronchitis in controlled clinical trials.
• Urinary Tract Infections (UTIs): Clinical studies suggest nasturtium may help prevent recurrent UTIs, with one controlled trial showing a 43.6% reduction in UTI incidence compared to placebo.
• Anti-inflammatory Properties: Experimental studies have demonstrated anti-inflammatory effects through inhibition of pro-inflammatory cytokines and NF-κB pathway.
• Antioxidant Activity: In vitro studies confirm significant antioxidant capacity due to flavonoids and vitamin C content.
• Wound Healing: Preliminary studies suggest application of nasturtium extract may accelerate wound healing through enhanced epithelialization and collagen synthesis.

Conditions with Limited or Preliminary Evidence

• Cardiovascular Health: Animal studies suggest potential benefits in reducing blood pressure and cholesterol levels, but human studies are lacking.
• Anticancer Potential: In vitro and animal studies indicate possible antiproliferative effects against certain cancer cell lines, particularly through the action of isothiocyanates, but clinical evidence is absent.
• Antidiabetic Effects: Preliminary animal studies suggest possible glucose-lowering effects, but human clinical trials are needed.

Recommended Dosages

Standardization and dosing recommendations for nasturtium vary based on preparation and indication:

• Urinary and Respiratory Infections: Most clinical trials have used commercially available preparations containing standardized extracts of nasturtium (standardized to glucotropaeolin content) in combination with horseradish. Typical adult dosages used in studies range from 200-400 mg of nasturtium extract (containing approximately 10-20 mg of glucotropaeolin) three times daily.
• Fresh Leaves/Flowers: Traditional use suggests 2-4 g of fresh plant material daily, but this is not standardized for active compounds.
• Tea/Infusion: 2-3 g of dried herb steeped in 150 ml hot water, taken 2-3 times daily.
• Tincture (1:5 in 45% alcohol): 2-4 ml taken 2-3 times daily.

It's important to note that many clinical studies have used nasturtium in combination with horseradish rather than as a monotherapy, making it difficult to establish precise dosage recommendations for nasturtium alone.

Side Effects and Safety Concerns

• Generally Recognized as Safe (GRAS): Nasturtium is considered generally safe when consumed in food amounts.
• Gastrointestinal Effects: Higher medicinal doses may cause mild gastrointestinal discomfort, including nausea or diarrhea in some individuals.
• Thyroid Function: Theoretical concerns exist about potential goitrogenic effects with long-term, high-dose use due to glucosinolate content, though clinical evidence of this effect is lacking.
• Pregnancy and Lactation: Insufficient safety data exists; therefore, medicinal doses are not recommended during pregnancy or breastfeeding.
• Drug Interactions: May theoretically interact with medications metabolized by cytochrome P450 enzymes, though clinical evidence is limited. Possible additive effects with other antibacterial agents.

High-Dose Studies and Knowledge Gaps

There is a notable lack of systematic toxicity studies examining doses significantly above the therapeutic range for nasturtium. The maximum tolerated dose and potential toxicity thresholds have not been thoroughly established in clinical research. Animal studies suggest low toxicity even at doses several times higher than therapeutic recommendations, but human data on high-dose administration is sparse. This represents a significant knowledge gap in the literature. No clear dose-response relationship has been established for most indications, and the optimal therapeutic window remains incompletely characterized.

Commercial Pharmaceutical Products

• Angocin®: A German pharmaceutical product containing standardized nasturtium and horseradish root extracts, approved for adjuvant therapy of acute infections of the bronchitis and sinusitis and for prevention and treatment of UTIs.
• Canephron®: Contains a combination of nasturtium, lovage root, and rosemary leaves, used for UTI treatment and prevention.
• Phytodolor®: Contains nasturtium in combination with ash bark and aspen bark, marketed for inflammatory rheumatic conditions.

Pure nasturtium pharmaceutical products are rare, as most commercial preparations combine it with other herbal ingredients, particularly horseradish.

Conclusion

Scientific evidence supports several traditional uses of nasturtium, particularly for respiratory and urinary tract infections when combined with horseradish. Its antimicrobial and anti-inflammatory properties are well-documented in laboratory and some clinical studies. However, many potential benefits require further investigation through rigorous clinical trials. The lack of standardization across studies and preparations makes precise dosage recommendations challenging. While generally recognized as safe in food amounts, medicinal doses should be approached with caution, particularly in special populations or those on multiple medications.

References

Bazylko, A., Granica, S., Filipek, A., Piwowarski, J., Stefańska, J., Osińska, E., & Kiss, A. K. (2013). Comparison of antioxidant, anti-inflammatory, antimicrobial activity and chemical composition of aqueous and hydroethanolic extracts of the herb of Tropaeolum majus L. Industrial Crops and Products, 50, 88-94.

Brondani, J. C., Cuelho, C. H. F., Marangoni, L. D., de Lima, R., Guex, C. G., de França Bonilha, I., & Manfron, M. P. (2016). Traditional usages, botany, phytochemistry, biological activity and toxicology of Tropaeolum majus L.-A review. Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas, 15(4), 264-273.

Conrad, A., Biehler, D., Nobis, T., Richter, H., Engels, I., Biehler, K., & Frank, U. (2013). Broad spectrum antibacterial activity of a mixture of isothiocyanates from nasturtium (Tropaeoli majoris herba) and horseradish (Armoraciae rusticanae radix). Drug research, 63(02), 65-68.

Goos, K. H., Albrecht, U., & Schneider, B. (2006). Efficacy and safety profile of a herbal drug containing nasturtium herb and horseradish root in acute sinusitis, acute bronchitis and acute urinary tract infection in comparison with other treatments in the daily practice/results of a prospective cohort study. Arzneimittel-forschung, 56(3), 249-257.

Tran, H. T. T., Márton, M. R., Herz, C., Maul, R., Baldermann, S., Schreiner, M., & Lamy, E. (2016). Nasturtium (Indian cress, Tropaeolum majus nanum) dually blocks the COX and LOX pathway in primary human immune cells. Phytomedicine, 23(6), 611-620.