# Brassica oleracea var. costata (Portuguese Kale)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/brassica-oleracea-var-costata
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-31
**Evidence Score:** 2 / 10
**Category:** Vegetable
**Also Known As:** Portuguese kale, Tronchuda cabbage, Tronchuda kale, Couve tronchuda, Portuguese cabbage, Brassica oleracea Tronchuda Group, Costata kale, Ribbed kale

## Overview

Portuguese kale (Brassica oleracea var. costata) is a traditional Iberian leafy vegetable containing glucosinolates, which are hydrolyzed by the enzyme myrosinase into bioactive isothiocyanates upon cell disruption. These isothiocyanates, including sulforaphane analogs, are studied for their potential to activate Nrf2-mediated [antioxidant](/ingredients/condition/antioxidant) pathways, though no clinical trials specific to this cultivar exist.

## Health Benefits

• No clinical health benefits documented - research contains only botanical classification data
• Glucosinolate content varies among Brassica oleracea cultivars (no specific data for Portuguese kale provided)
• No meta-analyses or RCTs available in the provided research
• No evidence quality can be assigned due to absence of clinical studies
• Further clinical research needed to establish health benefits

## Mechanism of Action

Like other Brassica oleracea cultivars, Portuguese kale contains glucosinolates such as glucoraphanin and sinigrin, which are enzymatically cleaved by myrosinase upon tissue damage to yield isothiocyanates and indoles. Isothiocyanates activate the Keap1-Nrf2 signaling pathway, upregulating [phase II detox](/ingredients/condition/detox)ification enzymes including glutathione S-transferases and NAD(P)H quinone oxidoreductase 1 (NQO1). Indole-3-carbinol and its condensation product diindolylmethane (DIM) additionally modulate aryl hydrocarbon receptor (AhR) activity and estrogen [metabolism](/ingredients/condition/weight-management), though cultivar-specific compound concentrations for B. oleracea var. costata have not been quantified in published literature.

## Clinical Summary

No randomized controlled trials, cohort studies, or meta-analyses have been conducted specifically on Brassica oleracea var. costata (Portuguese kale) in human subjects. General research on Brassica oleracea cultivars supports associations between glucosinolate-rich vegetable consumption and reduced [oxidative stress](/ingredients/condition/antioxidant) markers, but these findings cannot be directly extrapolated to Portuguese kale without cultivar-specific phytochemical profiling. Available literature on this variety is confined to botanical taxonomy, agronomic characterization, and regional dietary documentation from Portugal and Galicia. The current evidence base is insufficient to make any quantified health claims for this specific cultivar.

## Nutritional Profile

Brassica oleracea var. costata (Portuguese Kale/Couve Tronchuda) shares the general nutritional profile of Brassica oleracea leafy varieties with some cultivar-specific characteristics. Per 100g fresh weight (estimated from comparable Brassica oleracea leafy cultivars): Energy ~35-50 kcal; Protein ~2.5-4.0g (containing essential amino acids including lysine and methionine); Total carbohydrates ~5-7g; Dietary fiber ~2-3g (mix of soluble and insoluble fiber supporting gut motility); Fat ~0.4-0.7g (including small amounts of alpha-linolenic acid). Key micronutrients include Vitamin C (50-120mg, though cooking reduces this by 30-60%); Vitamin K1 (100-250µg, highly bioavailable, relevant for coagulation and bone [metabolism](/ingredients/condition/weight-management)); Folate (60-120µg DFE); Vitamin A activity via beta-carotene (~300-500µg RAE, fat-soluble, bioavailability enhanced with dietary fat); Calcium (100-150mg, though bioavailability is moderately reduced by oxalates, estimated absorption ~40-50%); Iron (1.5-2.5mg, non-heme, absorption enhanced by co-ingested Vitamin C); Potassium (~300-400mg); Magnesium (~25-35mg). Bioactive compounds include glucosinolates (sinigrin and glucobrassicin are predominant in Brassica oleracea leafy types; specific concentrations in var. costata not precisely documented but estimated 1-4µmol/g fresh weight); hydrolysis by myrosinase yields isothiocyanates (allyl isothiocyanate, indole-3-carbinol) upon cell disruption — cooking inactivates myrosinase, reducing conversion by ~50-70%. Flavonoids including kaempferol and quercetin glycosides (~0.5-2mg/100g) and hydroxycinnamic acids (chlorogenic acid) contribute to [antioxidant](/ingredients/condition/antioxidant) capacity. Chlorophyll content is notable (~50-100mg/100g). The broad, flat leaves of var. costata may reflect slightly different glucosinolate profiles compared to curly kale (B. oleracea var. sabellica), but cultivar-specific quantitative data remains sparse in published literature.

## Dosage & Preparation

No clinically studied dosage ranges available in the provided research. No preparation methods or bioavailability data documented. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

As a Brassica vegetable, Portuguese kale consumed in typical dietary amounts is generally recognized as safe for most healthy adults; however, high intake of raw cruciferous vegetables can inhibit [thyroid](/ingredients/condition/hormonal) iodine uptake due to goitrogenic compounds such as progoitrin, a concern particularly relevant for individuals with hypothyroidism or iodine deficiency. Individuals taking warfarin (Coumadin) should maintain consistent intake of all vitamin K-rich greens, including kale varieties, as fluctuations can interfere with INR stability. High cruciferous vegetable consumption may enhance the [metabolism](/ingredients/condition/weight-management) of certain drugs via CYP1A2 induction, potentially reducing the efficacy of substrates such as clozapine or theophylline. Pregnant individuals may consume Portuguese kale as a food source safely, but concentrated glucosinolate supplements are not recommended during pregnancy due to insufficient safety data.

## Scientific Research

No clinical trials, randomized controlled trials, or meta-analyses were found in the provided research dossier. The available data consists solely of taxonomic and botanical classification information without any PMIDs or clinical evidence.

## Historical & Cultural Context

No traditional medicinal uses or historical context provided in the research dossier. The available information only confirms its classification within the Brassica oleracea species group.

## Synergistic Combinations

Insufficient data to recommend synergistic ingredients

## Frequently Asked Questions

### What is Portuguese kale and how does it differ from regular kale?

Portuguese kale (Brassica oleracea var. costata), also called 'couve tronchuda' or 'Tronchuda cabbage,' is a distinct botanical variety of Brassica oleracea characterized by broad, flat leaves with prominent white midribs, originating in Portugal. Unlike curly kale (B. oleracea var. sabellica) or lacinato kale (var. palmifolia), its leaf morphology and glucosinolate profile are genetically distinct, though specific comparative phytochemical data between these cultivars in published research is limited.

### Does Portuguese kale contain sulforaphane?

Portuguese kale likely contains glucoraphanin, the glucosinolate precursor to sulforaphane, as this compound is widespread across Brassica oleracea cultivars; however, no published study has quantified glucoraphanin or sulforaphane concentrations specifically in B. oleracea var. costata. Sulforaphane is released from glucoraphanin only when myrosinase enzyme activity occurs, typically through chopping, chewing, or fermentation. Until cultivar-specific phytochemical analysis is published, sulforaphane content in Portuguese kale cannot be confirmed or compared to values reported for broccoli (approximately 73 µmol/100g fresh weight in some studies).

### Is Portuguese kale good for thyroid health?

Portuguese kale, like other Brassica oleracea varieties, contains goitrogenic glucosinolates such as progoitrin, which can be hydrolyzed to oxazolidine-2-thione, a compound that competes with iodine uptake in the thyroid gland. For individuals with adequate iodine intake and normal thyroid function, dietary consumption of Portuguese kale is unlikely to cause clinical hypothyroidism. However, individuals diagnosed with hypothyroidism or taking levothyroxine (Synthroid) are generally advised to avoid excessive raw cruciferous vegetable consumption and should consult an endocrinologist.

### What vitamins and minerals does Portuguese kale provide?

As a Brassica oleracea cultivar, Portuguese kale is expected to be a source of vitamin K1 (phylloquinone), vitamin C (ascorbic acid), folate (B9), calcium, and potassium, consistent with nutritional profiles documented for related kale varieties. Brassica oleracea var. costata is traditionally consumed in Portuguese cuisine as 'caldo verde' soup, suggesting significant dietary contribution of micronutrients in Iberian populations. Precise USDA or EFSA nutritional database entries specific to this cultivar are not currently published, making exact per-serving values unavailable.

### Can I take Portuguese kale as a supplement?

No standardized supplement form of Brassica oleracea var. costata (Portuguese kale) is currently available on the commercial market, and no clinical dosing guidelines exist for this specific cultivar. General cruciferous vegetable supplements typically standardize to glucosinolate content (e.g., 100–400 mg glucosinolates per serving) derived from more commercially available varieties such as broccoli sprout extract. Anyone seeking glucosinolate supplementation should look for products standardized to measurable glucoraphanin or sulforaphane content from validated sources rather than relying on Portuguese kale-specific products.

### Is Portuguese kale safe for people taking blood thinners or anticoagulant medications?

Portuguese kale, like other Brassica oleracea varieties, contains vitamin K, which plays a role in blood clotting and may interact with anticoagulants such as warfarin. If you are taking blood-thinning medications, consult your healthcare provider before significantly increasing Portuguese kale intake or supplementation. Consistent daily intake is more relevant than occasional consumption when considering potential interactions.

### How does Portuguese kale compare nutritionally to other common kale varieties like curly or lacinato kale?

Portuguese kale (Brassica oleracea var. costata) is a smooth-leafed variety with a milder flavor profile compared to the more bitter curly or textured lacinato varieties. While all kale varieties share similar nutrient profiles as members of the Brassica oleracea species, specific micronutrient concentrations and glucosinolate levels vary among cultivars, though direct comparative data for Portuguese kale is limited. Nutritional differences are generally modest across varieties, making variety choice primarily a matter of taste preference and culinary application.

### Can people with iodine deficiency or thyroid conditions safely consume large amounts of Portuguese kale?

While Brassica species contain goitrogens that may theoretically affect thyroid function in cases of severe iodine deficiency, moderate consumption of Portuguese kale as part of a varied diet is generally considered safe for most people, particularly those with adequate iodine intake. Individuals with existing thyroid conditions or iodine deficiency should maintain consistent intake levels and consult their healthcare provider rather than dramatically increasing consumption. Cooking kale reduces goitrogen content compared to raw consumption.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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