Broccoli

Food · Vegetable · Food, Typed Supps

Contains something no supplement quite copies — and it depends how you cook it.

Stage by stage

Intake (Chewing activates an enzyme): Chewing (or chopping) activates an enzyme that starts converting a precursor compound into sulforaphane.
Stomach (Vitamin C & K released): Digestion releases vitamin C, vitamin K, and fibre.
Small intestine (Sulforaphane & vitamins absorbed): Sulforaphane and vitamins are absorbed here, with gut bacteria also playing a role in sulforaphane formation.
Cells throughout the body (Antioxidant enzyme activation): Sulforaphane is studied for activating the body’s own antioxidant defense enzymes, a different mechanism than direct antioxidants.

Timing

Light steaming (versus boiling or overcooking) better preserves the enzyme needed to form sulforaphane.

Time to effect

Hours: Sulforaphane-related compounds are absorbed within hours of eating.

Allergens

None of the fourteen major allergens. Derived from what this food is, not from a product label.

Eating patterns

Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Keto, Gluten-free. Depends on the product: Low-FODMAP.

In season

June to November in the northern hemisphere, December to May in the southern.

Satiety

The satiety index is measured on 240 kcal servings. At 32 kcal per 100 g that is 750 g of this, which is not a serving anyone eats — so the index has nothing to say about it.

Environmental footprint

0.5 kg CO2e and 76 litres of freshwater per kg, matched to "Brassicas" in Poore & Nemecek (2018), Science 360.

Cost band

Cheap — roughly £2.5 per kg, as a band midpoint rather than a price.

Key nutrients

Vitamin C
Vitamin K
Sulforaphane precursor
Fiber

Nutrition per 100g

Calories: 32
Protein: 4g
Carbohydrate: 1.2g
of which sugars: 1.2g
Fat: 0.4g
of which saturated: 0g
Fibre: 3.5g
Sodium: 20mg

Food vs. supplement

No supplement fully replicates broccoli’s sulforaphane-forming system — it depends on an active enzyme plus a precursor compound working together, which is why overcooking (which destroys the enzyme) significantly reduces the effect compared to eating it raw or lightly steamed.

Kitchen tip

Steaming for 3 to 4 minutes preserves more sulforaphane-forming compounds than boiling, which leaches them into the water.

Common myth

“How you cook broccoli doesn’t affect its benefits.” In reality: Overcooking destroys the enzyme needed to convert its precursor compound into sulforaphane — preparation method genuinely matters here.