Nasturtium Benefits: What Research Shows About This Edible Herb

Nasturtiums (Tropaeolum majus) are best known as cheerful garden flowers, but the entire plant — leaves, flowers, and seeds — has a long history of use in both traditional cooking and herbal medicine. More recently, nutrition researchers have taken a closer look at the compounds nasturtiums contain and what those compounds do inside the body. Here's what the science generally shows.

What Makes Nasturtium Nutritionally Interesting

Nasturtiums are rich in several biologically active compounds:

• Vitamin C — both leaves and flowers contain meaningful amounts, though exact levels vary by growing conditions and freshness
• Glucosinolates — sulfur-containing compounds that break down into isothiocyanates, the same class of compounds found in broccoli and other cruciferous vegetables
• Carotenoids — including lutein and zeaxanthin in the flowers, particularly in orange and yellow varieties
• Flavonoids and polyphenols — plant-based antioxidants associated with reducing oxidative stress in cell-based and animal studies
• Isoquercitrin — a flavonoid compound under active research interest

Unlike many herbs that are consumed primarily as dried extracts, nasturtium is commonly eaten fresh, which affects how its nutrients are absorbed and how well the active compounds are preserved.

Glucosinolates and Isothiocyanates: The Core Research Focus 🔬

The most studied compounds in nasturtium are its glucosinolates, particularly glucotropaeolin. When chewed or crushed, glucotropaeolin converts — via the enzyme myrosinase — into benzyl isothiocyanate (BITC). This conversion is important: it's the isothiocyanate form, not the intact glucosinolate, that has been most studied for biological activity.

Laboratory and animal studies have examined BITC for antimicrobial properties, particularly against certain bacterial and fungal strains. Some studies have also investigated its potential in the context of antioxidant activity. That said, most of this research is preclinical — meaning it has been conducted in test tubes or animal models, not in clinical trials with human participants. Extrapolating those findings to what happens in a living human body requires caution.

The antimicrobial research is particularly interesting given nasturtium's traditional use for respiratory and urinary tract discomfort in European herbal medicine — though traditional use is not the same as clinical evidence of effect.

Antioxidant Activity and Carotenoid Content

Nasturtium flowers — especially orange and yellow varieties — contain carotenoids including lutein and zeaxanthin, compounds associated in population studies with eye health, particularly in relation to age-related macular changes. The evidence for lutein and zeaxanthin in eye health is among the stronger bodies of research for plant pigments, though most of that evidence comes from higher-dose supplementation studies, not from nasturtium consumption specifically.

The polyphenols and flavonoids in nasturtium leaves and flowers contribute to antioxidant capacity as measured in lab assays. Antioxidant capacity measured in a test tube, however, doesn't map directly to how antioxidants behave after digestion and absorption — a limitation that applies broadly to antioxidant research on plant foods.

Nutrient Profile at a Glance

Factors That Shape What You'd Actually Get

Even setting aside individual health differences, the bioavailability of nasturtium's active compounds depends on several variables:

Fresh vs. dried vs. extracted. The myrosinase enzyme responsible for converting glucosinolates into active isothiocyanates is heat-sensitive. Cooking nasturtium significantly reduces this conversion. Fresh consumption — eaten raw — preserves the enzymatic process better.

Seed, leaf, or flower. Glucosinolate concentration is highest in the seeds, followed by leaves, then flowers. Someone eating a small number of flowers as a garnish is getting a different phytochemical dose than someone regularly consuming leaves.

Gut microbiome. Even when myrosinase is inactivated by heat, gut bacteria can partially perform the same glucosinolate conversion — but individual microbiome composition varies enough that this pathway produces very different outcomes in different people. 🌿

Existing diet. Someone already eating a diet rich in cruciferous vegetables — broccoli, kale, arugula — is already getting substantial glucosinolate exposure. Nasturtium would be additive to that baseline, not a novel source.

Medications. Nasturtium contains vitamin K, which matters for anyone on anticoagulant medications. Its glucosinolates may also affect thyroid hormone metabolism at very high intakes, though normal culinary consumption is unlikely to be relevant at this level.

Who Tends to Use Nasturtium

Nasturtium appears in functional herbal contexts most often in relation to respiratory wellness, urinary health, and general antimicrobial support — reflecting its traditional European herbal history. Some commercial herbal formulations combine nasturtium with other plants for these purposes. Whether those applications produce meaningful effects in real-world use is an area where the clinical evidence is still thin compared to the preclinical data.

As a food, nasturtium is widely eaten across culinary traditions — particularly in South American cooking — and is generally considered safe for most people at typical culinary amounts.

What Remains Unanswered for Any Individual

The gap between what research shows in controlled studies and what a person actually experiences depends on factors the research can't account for: overall dietary patterns, health status, whether someone has conditions that affect nutrient absorption, what else they're taking, and how much nasturtium they'd realistically consume. Laboratory findings on glucosinolates are promising and worth following — but promising and proven are different things, and individual response varies considerably even when the compound in question is well understood.