Fermented Nasturtium Seeds

Heart health and circulation The most relevant human data comes from a small randomized crossover trial in which 10 adults with prediabetes consumed a freeze-dried nasturtium leaf drink (15 g weekly for 4 weeks). Participants saw their total antioxidant capacity increase and their oxidized LDL cholesterol — a form of LDL that is particularly damaging to artery walls — fall by roughly 13%. Oxidized LDL is considered a risk marker (a measurable sign that something unfavorable may be happening) rather than a hard cardiovascular outcome like a heart attack. No human studies have examined nasturtium's effect on blood pressure, full lipid panels, or actual cardiovascular events. And for the fermented seeds specifically, there is an important tension: the phytochemicals in the pods may support antioxidant activity, but the sodium in the brine could work against blood pressure control if portions are generous. For heart health, nasturtium capers are best used as a flavoring in small amounts rather than a primary intervention. Digestive health and gut microbiome Lacto-fermentation — the process of allowing naturally present lactic acid bacteria to acidify and preserve food in brine — is associated with gut-friendly outcomes in fermented vegetables generally. These bacteria and the organic acids they produce may support a diverse gut microbiome (the community of microorganisms living in your digestive tract). However, no studies have tested fermented nasturtium seed pods specifically for digestive outcomes or microbiome effects. On the antimicrobial side, benzyl isothiocyanate has been shown in laboratory studies to act against a range of bacteria, including some gut pathogens. This raises the theoretical possibility that nasturtium compounds could influence the gut's microbial balance — but this remains speculative until human gut studies are done. Anyone hoping for robust probiotic benefits should look to more studied fermented foods like kimchi, kefir, or sauerkraut as their primary sources. Blood sugar and metabolism In the same prediabetes crossover trial mentioned above, antioxidant markers improved but fasting blood glucose and glycated hemoglobin (HbA1c, a measure of average blood sugar over several weeks) did not show clinically meaningful changes. That study was not designed as a glucose-lowering intervention. As a condiment, fermented nasturtium seeds are negligible in calories and carbohydrates, which means they are unlikely to raise blood sugar. They can fit easily into a low-glycemic or whole-food plant-based diet. However, they should not be used as a substitute for proven blood sugar management strategies. Inflammation and oxidative stress A randomized, double-blind crossover trial in 34 healthy women tested nasturtium preparations with or without benzyl isothiocyanate at 1.5 g twice daily for two weeks. Both groups showed increased levels of prostaglandin E2 (PGE2), a lipid mediator — a signaling molecule derived from fats — involved in both pro-inflammatory and resolution phases of inflammation. This suggests a modulatory effect on the immune system, though the clinical significance of this change is not yet clear. A separate study in prediabetic adults showed reduced oxidized LDL after nasturtium consumption, which is relevant because oxidative stress (an imbalance between damaging free radicals and the body's defenses against them) drives chronic inflammation. These results are promising, but they used leaf preparations — not fermented seeds — so transferring the findings directly to the brined condiment requires caution. Antimicrobial and respiratory support The strongest clinical evidence for nasturtium comes from a randomized, double-blind, placebo-controlled trial of 384 patients with acute bronchitis, who received a combination phytomedicine (herbal medicine product) containing nasturtium herb and horseradish root. This group improved significantly faster on a bronchitis symptom score — including cough, mucus, and chest pain — than the placebo group over 10 days. This is meaningful evidence, but the product used was a standardized herbal medicine at therapeutic doses, not a brined condiment eaten by the teaspoon. Traditional use of nasturtium for urinary tract infections is based on the fact that benzyl isothiocyanate is excreted in urine, where it may have local antimicrobial effects. This mechanism is biologically plausible but has not been confirmed in modern clinical trials for urinary infections specifically.

Fermented nasturtium seed pods are the most food-friendly and kitchen-accessible form, but they are not the most studied. Here is how the main forms compare: Fermented green seed pods (nasturtium capers): Lowest calorie, peppery and tangy, excellent caper substitute. Best evidence angle is phytochemical intake via condiment use. Sodium content is a trade-off. No direct clinical trials. Fresh nasturtium leaves and flowers: The most studied form in human trials. Provide glucosinolates, flavonoids, vitamin C, and minerals. Used in salads and as edible garnishes. If health outcomes are your priority, leaves offer more direct research support. Freeze-dried leaf preparations: Used in the prediabetes antioxidant trial. Concentrated and standardized, but not a typical food product. Herbal combination products (nasturtium + horseradish): Most evidence for respiratory benefits comes from this medicinal form. Not appropriate to compare directly to culinary seed use. For everyday cooking, fermented seed pods deliver pungent flavor and phytonutrients in a condiment that adds zero-calorie interest to a meal. For medicinal-level effects, the research points to whole herb preparations rather than the seeds.

There are no established dietary guidelines or clinical dose recommendations for fermented nasturtium seeds. Human trials on nasturtium have used leaf or herb preparations ranging from 1.5 g twice daily (in capsule-style preparations) to 15 g of freeze-dried leaves weekly — amounts that do not translate directly to the brined pod condiment. As a culinary condiment, 1–2 teaspoons (roughly 5–10 g) per serving is a practical and widely used amount — similar to how you would use capers. This is the range where you get flavor and some phytochemical benefit without a problematic sodium load. Start low: If this is your first time eating nasturtium products, try a few pods and wait to see how your digestive system responds before increasing. The mustard oils are potent and can cause GI discomfort in sensitive individuals. Watch sodium across the day: If nasturtium capers are one of several salty condiments you use (soy sauce, olives, pickles, miso), factor the sodium into your overall daily tally.

The adventurous whole-food cook Looking to reduce capers' higher price without sacrificing pungency Wants to add a WFPB (whole-food, plant-based) fermented condiment to their rotation Grows nasturtiums in the garden and wants to use every part of the plant The antioxidant-aware eater Already managing oxidative stress risk through diet (e.g., prediabetes, family history of cardiovascular disease) Enjoys food-first approaches to supporting healthy inflammation responses Wants small, flavorful additions that bring phytochemical diversity without extra calories

Nasturtium seeds contain glucotropaeolin, which converts into benzyl isothiocyanate (BITC), a sulfur-containing mustard oil with documented antimicrobial and anti-inflammatory activity. They also provide flavonoids like isoquercitrin and other antioxidant phenolic compounds.

Nasturtium capers are made by packing fresh, green Tropaeolum majus seed pods into a sterilized jar with a brine of water, salt (2–3% by weight), and white wine vinegar. Optional aromatics like dill or bay leaf can be added before letting the jar sit for 3–7 days at room temperature.

Fermented nasturtium seeds are a flavorful, peppery substitute for traditional capers in dishes like lemon-caper vinaigrette, pasta puttanesca, or grain bowls. They pair well with roasted vegetables and can be chopped into tartare-style relishes with shallots and herbs.

Because they are brined, these seeds can contain 200 mg or more of sodium per tablespoon, which may affect those with high blood pressure, heart failure, or kidney disease. The mustard oils can also irritate the stomach lining in people with gastritis or peptic ulcers.

Yes, people with mustard allergies should proceed with caution when eating nasturtium seeds due to potential cross-reactivity. Both plants belong to families containing similar glucosinolate compounds that can trigger allergic responses.

Correct identification is essential: Tropaeolum majus has round shield-shaped leaves, funnel-shaped flowers in orange, yellow, or red, and three-lobed green seed pods. Never harvest or ferment seeds from a plant you cannot positively identify.

In the U.S., you can harvest nasturtium seeds from late spring through early autumn depending on your USDA Hardiness Zone. In southern states like California or Florida, they may produce year-round, while gardeners in the Northeast or Midwest typically harvest from July until the first frost.

While rarely found in major chains like Kroger or Safeway, you can often find nasturtium seeds for pickling at local farmers markets or through specialty CSA (Community Supported Agriculture) programs. Many U.S. home cooks also purchase organic seeds from suppliers like Johnny's Selected Seeds to grow their own for culinary use.

The FDA considers Tropaeolum majus generally safe for consumption, but you should ensure any seeds you harvest have not been treated with systemic pesticides. Always check that seeds purchased for planting are labeled "food grade" or "organic" if you intend to consume the resulting pods.

Nasturtium capers, often called "poor man's capers" in American culinary history, are a popular sustainable alternative to imported Mediterranean capers. They are frequently used in Pacific Northwest and Northeastern farm-to-table cuisine to provide a local, peppery zing to seafood and salads.