# Brassica rapa subsp. narinosa (Tat Soi)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/brassica-rapa-subsp-narinosa
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-24
**Evidence Score:** 2 / 10
**Category:** Vegetable
**Also Known As:** Brassica rapa subsp. narinosa, Tatsoi, Chinese flat cabbage, Tat soi, Tah tsai, Spoon mustard, Rosette bok choy

## Overview

Tat soi (Brassica rapa subsp. narinosa) is a leafy cruciferous vegetable that contains glucosinolates such as glucobrassicanapin and 4-methoxyglucobrassicin, which are enzymatically converted to bioactive isothiocyanates upon chewing or processing. These isothiocyanates drive its [antimicrobial](/ingredients/condition/immune-support) and potential chemoprotective effects through modulation of detoxification enzyme pathways.

## Health Benefits

• [Antimicrobial](/ingredients/condition/immune-support) properties: In vitro studies showed activity against Bacillus cereus (11.5-12mm inhibition zone) and multidrug-resistant Pseudomonas aeruginosa (evidence quality: preliminary)
• Rich in glucosinolates: Contains glucobrassicanapin, 4-methoxyglucobrassicin, neoglucobrassicin, and other glucosinolates common to cruciferous vegetables (evidence quality: preliminary)
• High phenolic content: Contains elevated levels of p-coumaric acid, kaempferol, and ferulic acid compared to related cultivars (evidence quality: preliminary)
• Carotenoid source: Contains β-carotene, 9Z-β-carotene, and lutein as identified through metabolite profiling (evidence quality: preliminary)
• Primary metabolite content: Rich in glucose, aspartic acid, and glutamic acid based on metabolomic analysis (evidence quality: preliminary)

## Mechanism of Action

Upon cell disruption, the enzyme myrosinase hydrolyzes tat soi's glucosinolates—including glucobrassicanapin and neoglucobrassicin—into isothiocyanates and indole compounds. These metabolites activate the Nrf2/ARE ([antioxidant](/ingredients/condition/antioxidant) response element) pathway, upregulating [phase II detox](/ingredients/condition/detox)ification enzymes such as glutathione S-transferase and quinone reductase. Additionally, 4-methoxyglucobrassicin-derived indole-3-carbinol metabolites may modulate estrogen receptor signaling and cytochrome P450 enzyme activity, particularly CYP1A1 and CYP1B1.

## Clinical Summary

Current evidence for tat soi is limited to in vitro studies; no human clinical trials have been conducted specifically on this subspecies. In vitro [antimicrobial](/ingredients/condition/immune-support) testing demonstrated inhibition zones of 11.5–12mm against Bacillus cereus and activity against multidrug-resistant Pseudomonas aeruginosa, classifying it as preliminary evidence only. Broader research on related Brassica rapa subspecies and their glucosinolate profiles in rodent models suggests [anti-inflammatory](/ingredients/condition/inflammation) and antiproliferative potential, but direct extrapolation to tat soi requires caution. The overall evidence quality is preclinical, and efficacy in humans has not been established.

## Nutritional Profile

Tatsoi (Brassica rapa subsp. narinosa) is a nutrient-dense leafy green with the following approximate profile per 100g fresh weight: Macronutrients: calories ~17-20 kcal, carbohydrates ~2.2g, protein ~1.5-2.0g, fat ~0.2g, dietary fiber ~1.5-2.0g. Micronutrients: Vitamin C approximately 45-60mg (50-67% DV), Vitamin K1 approximately 108-250µg (notably high, bioavailability enhanced by dietary fat co-consumption), Vitamin A (as beta-carotene) approximately 300-400µg RAE, folate approximately 60-80µg DFE, calcium approximately 105-135mg (bioavailability moderately reduced by oxalates, ~40-50% absorption rate), potassium approximately 250-300mg, magnesium approximately 18-22mg, iron approximately 0.9-1.4mg (non-heme, enhanced by co-consumed Vitamin C). Bioactive compounds: glucosinolates total approximately 15-30µmol/g dry weight including glucobrassicanapin, 4-methoxyglucobrassicin, and neoglucobrassicin; hydrolysis yields isothiocyanates and indoles upon cell disruption (chewing, chopping). Total phenolics approximately 200-400mg GAE/100g fresh weight including hydroxycinnamic acids (sinapic acid, caffeic acid derivatives) and flavonoids (quercetin, kaempferol glycosides). Chlorophyll content notable at approximately 50-100mg/100g. Carotenoids include lutein and zeaxanthin (~2-4mg/100g), relevant to ocular health. Bioavailability note: light cooking (blanching <2 min) preserves glucosinolate content better than boiling; fat-soluble vitamins (K, A, carotenoids) require dietary fat for optimal absorption; myrosinase enzyme activity responsible for glucosinolate hydrolysis is partially inactivated by cooking but gut microbiota can partially compensate.

## Dosage & Preparation

No clinically studied dosage ranges are available as no human trials exist. Tatsoi is consumed as a whole food vegetable without standardization, typically eaten fresh in salads or cooked in soups and stir-fries. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Tat soi is generally recognized as safe when consumed as a food at typical culinary amounts, with no documented serious adverse effects in healthy adults. High intake of glucosinolate-rich brassicas may suppress [thyroid function](/ingredients/condition/hormonal) by interfering with iodine uptake, making it a potential concern for individuals with hypothyroidism or those on thyroid medications such as levothyroxine. Indole compounds derived from its glucosinolates can induce cytochrome P450 enzymes (CYP1A2, CYP3A4), theoretically altering the [metabolism](/ingredients/condition/weight-management) of drugs including warfarin, cyclosporine, and certain chemotherapy agents. Safety data during pregnancy and lactation is insufficient; consumption at normal food quantities is likely safe, but high-dose supplemental forms should be avoided until further research is available.

## Scientific Research

No human clinical trials, randomized controlled trials, or meta-analyses specifically on Brassica rapa subsp. narinosa (tatsoi) were identified in the available research. Current evidence is limited to in vitro metabolite profiling studies and [antimicrobial](/ingredients/condition/immune-support) assays, with no PubMed PMIDs for human intervention studies available.

## Historical & Cultural Context

Tatsoi has been cultivated especially in China as 'Chinese flat cabbage' or 'tah tsai,' primarily as a food crop rather than in formal traditional medicine systems. No specific historical medicinal uses or traditional medicine applications are documented in the available sources.

## Synergistic Combinations

Bok choy, Chinese cabbage, kale, broccoli, spinach

## Frequently Asked Questions

### What glucosinolates are found in tat soi?

Tat soi contains several identified glucosinolates including glucobrassicanapin (an aliphatic glucosinolate), 4-methoxyglucobrassicin, neoglucobrassicin, and additional indolic glucosinolates. These compounds are hydrolyzed by the endogenous enzyme myrosinase into bioactive isothiocyanates and indoles when the plant tissue is disrupted by chewing or cooking. The specific glucosinolate profile distinguishes tat soi from other Brassica rapa subspecies such as turnip or pak choi.

### Does tat soi have antimicrobial properties?

In vitro studies have shown tat soi extracts produce inhibition zones of 11.5–12mm against Bacillus cereus and demonstrate measurable activity against multidrug-resistant Pseudomonas aeruginosa. These effects are attributed to isothiocyanate compounds derived from its glucosinolates, which disrupt bacterial cell membranes and inhibit enzyme function. However, these findings are preliminary in vitro data and have not been confirmed in human or animal infection models.

### How does tat soi compare to other cruciferous vegetables nutritionally?

Tat soi shares the core glucosinolate-based bioactive profile of cruciferous vegetables but has a distinct glucosinolate composition, notably containing neoglucobrassicin and 4-methoxyglucobrassicin at measurable levels, differentiating it from broccoli (rich in glucoraphanin) and cabbage (rich in sinigrin). Like other brassicas, it provides vitamins C and K, folate, and carotenoids, while its dense rosette leaf structure contributes relatively high nutrient density per gram. Comparative quantitative studies against other Brassica rapa varieties are limited, making precise nutritional ranking difficult.

### Can tat soi affect thyroid function?

Yes, tat soi contains glucosinolates that, upon hydrolysis, produce goitrogenic compounds capable of competing with iodine uptake in the thyroid gland, potentially reducing thyroid hormone synthesis with very high or chronic intake. This risk is most relevant for individuals with pre-existing hypothyroidism or iodine deficiency, as adequate iodine status typically offsets the goitrogenic effect at normal dietary amounts. Cooking deactivates a significant portion of myrosinase enzyme activity, reducing but not eliminating the goitrogenic potential of the raw vegetable.

### Is there a recommended dosage for tat soi supplements?

No standardized supplemental dosage for tat soi has been established, as there are currently no human clinical trials defining therapeutic doses for any specific health outcome. As a whole food, tat soi is typically consumed in serving sizes of 85–150g (3–5 oz) in culinary contexts, consistent with general cruciferous vegetable intake recommendations of 2–3 servings per week. Any commercially available tat soi extract or supplement should be evaluated for glucosinolate content standardization, and individuals on medications metabolized by CYP enzymes should consult a healthcare provider before supplementation.

### What is the bioavailability of glucosinolates in tat soi, and does cooking affect their absorption?

Glucosinolates in tat soi are converted to active isothiocyanates through the enzyme myrosinase, which is partially deactivated by heat, reducing bioavailability when cooked. Raw or lightly steamed tat soi preserves more myrosinase activity and maximizes glucosinolate bioconversion in the digestive tract. The presence of stomach acid and gut microbiota also influences the final yield of bioactive compounds from dietary tat soi.

### Is tat soi safe for pregnant women or breastfeeding mothers?

Tat soi is a whole food vegetable with a long history of safe consumption in Asian cuisines and is generally recognized as safe for pregnant and breastfeeding women when consumed as food. However, concentrated tat soi supplements contain high levels of glucosinolates and goitrogens, which may warrant medical consultation during pregnancy due to potential thyroid impacts on fetal development. Whole tat soi vegetables in typical dietary amounts pose minimal risk.

### What does current research show about tat soi's effectiveness for antimicrobial or cancer-prevention claims?

Current evidence for tat soi's antimicrobial properties is preliminary, limited to in vitro studies showing inhibition zones against specific bacteria like Bacillus cereus and multidrug-resistant Pseudomonas aeruginosa. Cancer-prevention claims are based on the presence of glucosinolates and phenolic compounds common to cruciferous vegetables, but human clinical trials specifically on tat soi are lacking. More robust clinical research is needed before making definitive health claims beyond its nutritional profile as a USDA nutrient-dense food.

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