# Choy Sum (Brassica chinensis var. parachinensis)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/choy-sum
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-31
**Evidence Score:** 2 / 10
**Category:** Vegetable
**Also Known As:** Brassica rapa subsp. chinensis var. parachinensis, Brassica chinensis var. parachinensis, Chinese flowering cabbage, Chinese white cabbage, Cai xin, Choi sum, Yu choy sum, Flowering pak choi, Chinese broccoli rabe, Choy sim

## Overview

Choy sum (Brassica chinensis var. parachinensis) is a leafy cruciferous vegetable whose primary bioactive glucosinolates, particularly gluconapin, are hydrolyzed by myrosinase into isothiocyanates that induce [phase II detox](/ingredients/condition/detox)ification enzymes. These compounds, including NQO1 and GSTA3 activators, may support cellular [antioxidant](/ingredients/condition/antioxidant) defense and postprandial lipid regulation based on preliminary laboratory and animal evidence.

## Health Benefits

• May support detoxification enzyme activity through glucosinolate compounds that induce phase II enzymes like NQO1 and GSTA3 (preliminary evidence from cell studies)
• Could help manage postprandial blood lipids as gluconapin prevented hypertriglyceridemia in mice (animal study evidence only)
• Potential [anti-inflammatory](/ingredients/condition/inflammation) effects shown by progoitrin protecting against acute pancreatitis in Swiss mice (preclinical evidence)
• Rich source of flavonoids including kaempferol (36.0-102.6 mg/100g) and quercetin (14.5-52.4 mg/100g) with [antioxidant](/ingredients/condition/antioxidant) properties (phytochemical analysis)
• Provides beta-carotene (1360 µg/100g raw) and is low in sodium (13 mg/100g) as a nutrient-dense vegetable (nutritional analysis)

## Mechanism of Action

Glucosinolates in choy sum, predominantly gluconapin, are converted by the enzyme myrosinase upon cell disruption into bioactive isothiocyanates such as but-3-enyl isothiocyanate. These isothiocyanates activate the Nrf2-Keap1 transcription pathway, upregulating [phase II detox](/ingredients/condition/detox)ification enzymes including NAD(P)H quinone oxidoreductase 1 (NQO1) and glutathione S-transferase alpha 3 (GSTA3), which conjugate electrophilic toxins for excretion. Gluconapin has also been observed in murine models to inhibit postprandial hypertriglyceridemia, possibly through modulation of lipase activity or chylomicron assembly in enterocytes.

## Clinical Summary

Current evidence supporting choy sum's health effects derives primarily from in vitro cell studies and rodent models, with no published randomized controlled trials in humans specific to this vegetable. Cell culture studies have demonstrated induction of NQO1 and GSTA3 by isothiocyanate fractions derived from Brassica chinensis var. parachinensis extracts, though concentrations used often exceed typical dietary exposure. A mouse study found that gluconapin administration prevented diet-induced postprandial hypertriglyceridemia, but species differences and gavage dosing limit extrapolation to human dietary intake. Overall, the evidence base is preliminary, and choy sum's benefits in humans remain inferred from broader cruciferous vegetable research rather than ingredient-specific clinical trials.

## Nutritional Profile

Per 100 g raw edible portion: Water ~93 g; Energy ~13–16 kcal; Protein ~1.2–1.7 g; Total fat ~0.3 g; Carbohydrates ~1.9–2.5 g; Dietary fiber ~1.0–1.2 g. Vitamins: Vitamin C ~45–55 mg (high; bioavailability good but heat-labile, reduced 30–50% by stir-frying/boiling), Vitamin A (as β-carotene) ~2600–3200 µg RAE equivalent (~260–320 µg retinol activity; fat-soluble, bioavailability enhanced when consumed with oil), Vitamin K₁ (phylloquinone) ~60–80 µg, Folate (B9) ~66–80 µg (moderate bioavailability ~50–70% from food matrix), Riboflavin (B2) ~0.07 mg, Vitamin B6 ~0.15 mg. Minerals: Calcium ~100–120 mg (bioavailability moderate ~40%, higher than spinach due to low oxalate content ~0.3–0.5 mg/g), Potassium ~250–300 mg, Iron ~1.0–1.5 mg (non-heme; bioavailability ~5–12%, enhanced by concurrent vitamin C), Magnesium ~18–22 mg, Phosphorus ~35–45 mg, Zinc ~0.3–0.5 mg, Manganese ~0.15–0.20 mg. Bioactive compounds: Total glucosinolates ~15–45 µmol/g dry weight, dominated by gluconapin (3-butenyl glucosinolate, often >50% of total glucosinolates), progoitrin (2-hydroxy-3-butenyl glucosinolate), and smaller amounts of glucobrassicin (indol-3-ylmethyl glucosinolate) and 4-methoxy-glucobrassicin; upon tissue disruption, myrosinase converts these to bioactive isothiocyanates and nitriles—cooking partially inactivates myrosinase, reducing conversion efficiency by ~30–60% but gut microbiota can also hydrolyze intact glucosinolates. Carotenoids: Lutein ~3.5–5.5 mg/100 g, β-carotene ~1.5–2.5 mg/100 g (bioavailability improved 2–3× with dietary fat). Phenolic compounds: Total phenolics ~50–120 mg GAE/100 g fresh weight, including kaempferol glycosides (~5–15 mg/100 g), isorhamnetin glycosides, and hydroxycinnamic acids (sinapic acid, ferulic acid derivatives). Chlorophyll: ~30–60 mg/100 g fresh weight in leaves. Notable: Very low in oxalates relative to other leafy greens, making calcium and iron comparatively more bioavailable; low in anti-nutritional phytates. Sodium content is naturally low (~10–15 mg/100 g). Choy sum flowering stalks may have slightly higher sugar content (~2.5–3.0 g/100 g) and slightly lower fiber than leaves.

## Dosage & Preparation

No clinically studied dosage ranges are available for Choy Sum extracts, powders, or standardized forms as no human trials exist. Studies report glucosinolate concentrations in leaves (total aliphatic GSLs 8243-18,110 µmol/kg dry weight), but no standardization or dosing protocols for biomedical use have been established. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Choy sum is generally recognized as safe when consumed as a food in typical culinary quantities, with no documented serious adverse effects in healthy adults. As a goitrogenic cruciferous vegetable, high habitual intake may marginally suppress [thyroid](/ingredients/condition/hormonal) iodine uptake due to isothiocyanate interference with the sodium-iodide symporter, particularly relevant for individuals with pre-existing hypothyroidism or iodine deficiency. Individuals taking warfarin or other vitamin K-dependent anticoagulants should maintain consistent intake, as choy sum contains vitamin K which can alter anticoagulant efficacy. Safety data during pregnancy and lactation are insufficient for concentrated extracts, though normal dietary consumption is not considered a concern.

## Scientific Research

No human clinical trials, RCTs, or meta-analyses specific to Choy Sum have been conducted. Current research is limited to phytochemical isolation studies and preclinical investigations in cell cultures (Hep G2 cells) and animal models (Swiss mice, rats) examining glucosinolate compounds and their metabolites.

## Historical & Cultural Context

Choy Sum is primarily used as a culinary vegetable in Chinese cuisine and is noted as one of the most popular vegetables in China. No documented historical use in traditional medicine systems including TCM was identified, with current research focusing on modern phytochemical analysis rather than ethnobotanical applications.

## Synergistic Combinations

Broccoli sprouts, Turmeric, Green tea extract, Milk thistle, N-acetylcysteine

## Frequently Asked Questions

### What is the main active compound in choy sum?

The primary bioactive compounds in choy sum are glucosinolates, with gluconapin being the predominant form in Brassica chinensis var. parachinensis. Upon chopping or chewing, the enzyme myrosinase converts gluconapin into but-3-enyl isothiocyanate, which is responsible for most of the vegetable's observed biological activity including enzyme induction and potential lipid-lowering effects.

### Can choy sum help lower triglycerides?

Animal research has shown that gluconapin, the primary glucosinolate in choy sum, prevented postprandial hypertriglyceridemia in mice fed a high-fat challenge, suggesting interference with dietary fat absorption or chylomicron metabolism. However, no human clinical trials have replicated this finding, and the doses administered in mouse studies via gavage are not directly comparable to amounts consumed through normal dietary intake of choy sum.

### Is choy sum safe for people with thyroid conditions?

Choy sum contains isothiocyanates that can competitively inhibit the sodium-iodide symporter in thyroid tissue, potentially reducing iodine uptake and thyroid hormone synthesis with very high or chronic intake. Individuals with hypothyroidism or iodine deficiency should avoid consuming very large amounts of raw choy sum regularly, though normal cooked portions are unlikely to pose a clinically meaningful risk. Consulting a physician or dietitian is advised for those on thyroid medication such as levothyroxine.

### How does choy sum support detoxification?

Isothiocyanates derived from choy sum's glucosinolates activate the Nrf2 transcription factor by displacing its repressor Keap1, triggering upregulation of phase II detoxification enzymes including NQO1 (NAD(P)H quinone oxidoreductase 1) and GSTA3 (glutathione S-transferase alpha 3). These enzymes catalyze the conjugation of reactive electrophiles and oxidative metabolites to glutathione, facilitating their urinary excretion and reducing cellular DNA damage risk. This mechanism has been demonstrated in cell culture studies but requires confirmation in human intervention trials.

### Does cooking choy sum destroy its health benefits?

Cooking choy sum, especially boiling, significantly reduces myrosinase enzyme activity and leaches water-soluble glucosinolates, which can lower the conversion efficiency to bioactive isothiocyanates by up to 30–60% compared to raw consumption. However, human gut microbiota harbor bacteria capable of hydrolyzing glucosinolates independently of plant myrosinase, partially compensating for cooking losses. Light steaming or stir-frying preserves more glucosinolate content than prolonged boiling, and adding raw mustard powder (which contains active myrosinase) to cooked choy sum can restore some conversion capacity.

### What is the difference between choy sum and other cruciferous vegetables like broccoli or bok choy in terms of glucosinolate content?

Choy sum contains glucosinolates including gluconapin and progoitrin, similar to other Brassica species, but the specific concentration and profile may vary. While broccoli is often highlighted for sulforaphane (from glucoraphanin), choy sum's gluconapin and progoitrin have shown distinct bioactivity in animal studies for lipid management and anti-inflammatory effects. Direct comparative human studies on glucosinolate levels between these vegetables are limited, making it difficult to definitively rank their potency.

### Is choy sum safe to consume regularly for people taking blood-thinning medications?

Choy sum contains vitamin K, which plays a role in blood clotting and may theoretically interact with anticoagulants like warfarin if consumption varies dramatically. People taking blood-thinning medications should maintain consistent intake of choy sum rather than alternating between high and low consumption, and should consult their healthcare provider about their specific medication. The vitamin K content in choy sum is not prohibitive for most users but requires monitoring, especially if warfarin dosing is involved.

### What does current research show about the strength of evidence for choy sum's health benefits?

Most evidence supporting choy sum's detoxification and anti-inflammatory effects comes from preliminary cell studies and animal models, rather than human clinical trials, which limits the certainty of these benefits. The glucosinolate compounds in choy sum show promise for enzyme induction and postprandial lipid management in controlled settings, but translating these findings to human supplementation requires further investigation. As a whole food, choy sum is nutrient-dense and safe, but claims about specific disease prevention should be considered preliminary until larger human studies are conducted.

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