Contents
What it is
Broccoli is a cultivated form of the same species as cabbage, grown for its cluster of unopened flower buds and its stalk. Cabbage, cauliflower, kale and Brussels sprouts are all varieties bred from that one species. Broccoli itself was developed around the Mediterranean. When the buds start yellowing the head is about to flower, and the flavour falls off. The stalk is good too once the tough outer skin is pared away. Long boiling wrecks both colour and texture, so it is better blanched briefly or steamed.
Scientific name Brassica oleracea var. italica
Broccoli does not contain ready-made sulforaphane. It forms when a precursor called glucoraphanin meets an enzyme called myrosinase, which only happens once cells are broken.
The catch is that this enzyme is heat-sensitive. Boil a whole head for a long time and the precursor survives while almost no sulforaphane forms. With broccoli, how you handle it matters more than what is in it.
Key benefits
- Early research
Sulforaphane switches on detoxification enzymes
It activates the Nrf2 pathway, the cell's defence switch, increasing production of phase-two detoxification enzymes. This mechanism is the one most often cited to explain observational links between cruciferous vegetables and lower risk of some cancers.[1]
- Nutrition data
More vitamin C than lemon
89 mg per 100 g beats lemon (53 mg) by weight. Because it is water-soluble, though, long boiling washes out nearly half. Steaming or a quick sauté keeps more.
- Nutrition data
Vitamin K for bone and clotting
100 g covers most of an adult's daily requirement. Vitamin K is needed to activate the proteins that direct calcium into bone.
- Nutrition data
Fibre for fullness and gut bacteria
2.6 g per 100 g at only 34 kcal — a high ratio. That makes broccoli an easy way to add volume to a meal without adding much energy.
How to eat it well
- Steam for three minutes or less. Steaming preserves far more sulforaphane and vitamin C than boiling.
- If you overcook it, add mustard or radish. Their myrosinase substitutes for the enzyme destroyed by heat.
- Eat the stem. Peeled, it is as tender as the florets and higher in fibre.
- Frozen broccoli is blanched before freezing, so it has no active enzyme. Pairing it with mustard makes up for that.
- Chopping it and waiting about 40 minutes before cooking lets sulforaphane form in advance, reducing heat losses.
How to read the grades
Each benefit carries a label showing how far research on people supports it. Grades differ between items even within the same ingredient.
- Nutrition data
- A fact verifiable from food composition databases or health authorities. This is a different kind of statement from a clinical effect.
- Strong evidence
- Consistently confirmed across randomised controlled trials or meta-analyses.
- Moderate evidence
- Human studies exist, but effect sizes are small or results are mixed.
- Early research
- Cell or animal work, or small preliminary studies.
- Not established
- Commonly claimed, but not confirmed in studies on people.
What to watch out for
- On warfarin, keep vitamin K intake steady rather than increasing it suddenly.
- In hypothyroidism, large amounts of raw cruciferous vegetables can interfere with iodine uptake. Cooking largely resolves this.
- Raffinose and related oligosaccharides can cause gas and bloating in irritable bowel syndrome.
- If you have a history of kidney stones, avoid very large portions.
Nutrition
Approximate values per 100 g edible portion.
- Calories
- 34 kcal2%
- Carbohydrates
- 6.6 g2%
- Fiber
- 2.6 g9%
- Protein
- 2.8 g6%
- Fat
- 0.4 g<1%
- Vitamin C
- 89 mg99%
- Vitamin A
- 31 µg3%
- Vitamin E
- 0.78 mg5%
- Vitamin K
- 102 µg85%
- Folate
- 63 µg16%
- Potassium
- 316 mg7%
Percentages are of the US FDA Daily Value for adults and children 4 and over. National reference intakes differ by sex and age.
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Key nutrients
Dishes with this ingredient
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Sources
The databases and health authorities this article's nutrition figures and health statements draw on.
- 1Randomized Crossover Trial Evaluating Detoxification of Tobacco Carcinogens by Broccoli Seed and Sprout Extract in Current SmokersClinical trialBauman JE, et al. Cancers (Basel) 2022PMID 35565256
- 2USDA FoodData CentralFood composition database
- 3NIH Office of Dietary SupplementsHealth authority
- 4PubMedResearch literature
