Rocket

Food · Vegetable · Food, Typed Supps

Rocket is in the mustard family, not the lettuce family, and that is where the peppery taste comes from.

Stage by stage

Intake (Mouth): Chewing brings myrosinase and glucosinolates together, generating the peppery isothiocyanates.
Breakdown (Stomach): Soft cell walls yield quickly; the leaf is around 90% water by weight.
Absorption (Small intestine): Calcium, folate and fat-dependent beta-carotene are absorbed; low oxalate aids calcium uptake.
Use (Bone, retina and dividing cells): Calcium supports bone, beta-carotene becomes vitamin A, and folate supports cell division.

Time to effect

Weeks: Folate and carotenoid status shift over weeks of regular intake, not from a single salad.

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

April to October in the northern hemisphere, October to April in the southern.

Satiety

The satiety index is measured on 240 kcal servings. At 22 kcal per 100 g that is 1.1 kg 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

Mid — roughly £9 per kg, as a band midpoint rather than a price.

Key nutrients

Nutrition per 100g

Calories: 22
Protein: 3.3g
Carbohydrate: 0.3g
of which sugars: 0.3g
Fat: 0.3g
of which saturated: 0g
Fibre: 2.4g
Sodium: 47mg

Food vs. supplement

As a calcium source rocket is well absorbed but the per-serve amount is small, so it supports intake rather than replacing dairy or a supplement for someone with a real deficit. For folate and beta-carotene it is a genuinely efficient food source, and beta-carotene from food carries none of the lung cancer signal seen with high-dose beta-carotene supplements in smokers.

Kitchen tip

Dress it with oil. Beta-carotene absorption depends on fat being present in the same meal, and a few grams of olive oil raise carotenoid uptake substantially — which is one reason the traditional pairing with oil and parmesan makes nutritional as well as culinary sense.

Common myth

“Spinach is the best green for calcium.” In reality: Spinach lists more calcium but binds most of it as calcium oxalate, and only about 5% is absorbed. Rocket is a low-oxalate brassica with absorption near 50%, so a serve of rocket can deliver more usable calcium than a serve of spinach.

In the glossary

Absorption