# Brassica oleracea var. caulorapa (Collard Greens) **Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/brassica-oleracea-var-caulorapa **Data Source:** Hermetica Superfoods Ingredient Encyclopedia **Updated:** 2026-03-29 **Evidence Score:** 2 / 10 **Category:** Vegetable **Also Known As:** kohlrabi, German turnip, turnip cabbage, cabbage turnip, stem turnip, Brassica oleracea var. gongylodes, Kohlrübe, chou-rave ## Overview Collard greens (Brassica oleracea var. acephala) contain glucosinolates that convert to bioactive isothiocyanates when chewed or chopped. These compounds activate [phase II detox](/ingredients/condition/detox)ification enzymes and may support cellular protection through the Nrf2 pathway. ## Health Benefits • No clinical health benefits documented - search results contain no human trials for kohlrabi specifically • Contains glucosinolates similar to other B. oleracea varieties (compositional data only, no clinical outcomes) • May share general cruciferous vegetable properties (no specific evidence provided) • Traditional culinary use since 1554 but no medicinal applications documented • Related cabbage varieties show phenolic compounds up to 288.3 mg/100g fresh weight (compositional analysis only, not clinical benefit) ## Mechanism of Action Glucosinolates in collard greens are hydrolyzed by myrosinase enzyme to form isothiocyanates like sulforaphane. These compounds activate the Nrf2-ARE pathway, inducing [phase II detox](/ingredients/condition/detox)ification enzymes including glutathione S-transferase and quinone reductase. Isothiocyanates also modulate [inflammatory pathway](/ingredients/condition/inflammation)s by inhibiting NF-κB activation. ## Clinical Summary No clinical trials have specifically tested collard greens as an isolated intervention. Available evidence comes from observational studies on cruciferous vegetable consumption and mechanistic research on glucosinolate compounds. Most human studies examine mixed cruciferous vegetable intake rather than collard greens specifically. The health effects are largely extrapolated from research on other Brassica oleracea varieties and their shared bioactive compounds. ## Nutritional Profile Collard greens (Brassica oleracea var. viridis) are a nutrient-dense leafy vegetable. Per 100g raw: Calories 32 kcal, Carbohydrates 5.4g, Dietary Fiber 3.6g, Protein 3.0g, Fat 0.6g. Key vitamins: Vitamin K1 (phylloquinone) 437µg (364% DV) - among highest plant sources; Vitamin C 35.3mg (39% DV); Vitamin A as beta-carotene 251µg RAE; Folate 166µg (42% DV); Vitamin B6 0.165mg; Riboflavin 0.13mg; Thiamine 0.054mg. Key minerals: Calcium 232mg (18% DV) - notably high for a leafy green; Manganese 0.659mg; Potassium 213mg; Magnesium 27mg; Phosphorus 25mg; Iron 0.47mg. Bioactive compounds: Glucosinolates including glucoraphanin and sinigrin (precursors to sulforaphane and allyl isothiocyanate upon myrosinase activation by chopping or chewing); Lutein and zeaxanthin approximately 3.7mg per 100g (bioavailability enhanced with dietary fat); Kaempferol and quercetin as predominant flavonoids; Chlorophyll a and b contributing to [antioxidant](/ingredients/condition/antioxidant) capacity. Bioavailability notes: Calcium bioavailability is approximately 40-60% (superior to spinach which contains high oxalates); Vitamin K and carotenoid absorption significantly improved when consumed with fat; cooking reduces glucosinolate content by 30-60% but does not substantially affect mineral content; oxalate content is relatively low compared to other dark leafy greens, supporting better mineral absorption. ## Dosage & Preparation No clinically studied dosage ranges are available as kohlrabi is researched and consumed as a whole food vegetable rather than a standardized supplement or extract. No therapeutic dosing information exists. Consult a healthcare provider before starting any new supplement. ## Safety & Drug Interactions Collard greens are generally safe when consumed as food but contain goitrogens that may interfere with [thyroid function](/ingredients/condition/hormonal) in susceptible individuals. High vitamin K content may interact with warfarin and other anticoagulant medications. Raw collard greens contain higher levels of goitrogenic compounds compared to cooked varieties. Pregnant and breastfeeding women should consume normal dietary amounts without concern. ## Scientific Research No clinical trials, randomized controlled trials, or meta-analyses were found specifically for Brassica oleracea var. caulorapa (kohlrabi). The only available research consists of compositional analyses of related B. oleracea varieties showing glucosinolate and phenolic content, but these lack clinical outcome data or PMIDs. ## Historical & Cultural Context Kohlrabi has been cultivated as a food crop since at least 1554 in northern Europe, valued for its edible swollen stem with a milder, sweeter flavor than turnips. Search results provide no evidence of traditional medicinal uses in systems like Ayurveda, TCM, or European herbalism - it appears to be exclusively a culinary vegetable. ## Synergistic Combinations Other cruciferous vegetables, cabbage, kale, broccoli, Brussels sprouts ## Frequently Asked Questions ### Do collard greens contain more glucosinolates than other cruciferous vegetables? Collard greens contain moderate levels of glucosinolates compared to other Brassica vegetables. Brussels sprouts and broccoli typically contain higher concentrations, while cabbage contains similar amounts. ### Should people with thyroid problems avoid collard greens? People with thyroid conditions should moderate raw collard green intake due to goitrogenic compounds. Cooking significantly reduces goitrogen activity, making cooked collard greens safer for those with thyroid concerns. ### How much vitamin K is in collard greens? One cup of cooked collard greens provides approximately 770 micrograms of vitamin K, which is over 600% of the daily value. This high content requires monitoring for people taking blood-thinning medications. ### Are collard greens better raw or cooked for health benefits? Cooking collard greens reduces goitrogenic compounds and increases bioavailability of some nutrients like beta-carotene. However, light steaming preserves more glucosinolates and myrosinase enzyme activity compared to boiling. ### Can collard greens help with detoxification? Collard greens contain compounds that support the body's natural detoxification processes by inducing phase II liver enzymes. However, no clinical studies have directly measured detoxification effects from collard green consumption specifically. ### What is the difference between collard greens and other B. oleracea varieties like kale and cabbage? Collard greens, kale, and cabbage are all varieties of Brassica oleracea but differ in leaf structure and culinary use. Collard greens have larger, smoother leaves compared to kale's frilly texture, and they contain similar glucosinolate profiles to other cruciferous vegetables. While all three are nutrient-dense, collard greens have historically been a dietary staple in Southern and African cuisines since the 1554 period of documentation. ### Can I get sufficient nutrients from eating collard greens instead of taking supplements? Collard greens are classified as USDA nutrient-dense foods and provide substantial amounts of vitamin K, calcium, and fiber through whole food consumption. A single serving of cooked collard greens can contribute significantly to daily nutrient requirements, making them an effective dietary source rather than requiring supplementation. However, the choice between whole food and supplements depends on individual dietary patterns and nutrient gaps. ### Are collard greens safe for everyone to eat regularly, including children and pregnant women? Collard greens are safe for most populations, including children and pregnant women, as they are conventional food with a long history of culinary use. The primary consideration is the high vitamin K content, which may interact with blood-thinning medications—not the vegetable itself. As with any food, individual tolerance should be considered, but collard greens are generally recognized as safe when consumed as part of a balanced diet. --- *Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com* *License: CC BY-NC-SA 4.0 — Attribution required. Commercial use: admin@hermeticasuperfoods.com*