Watercress
Food · Vegetable · Food, Typed Supps
Watercress is a peppery little green that punches way above its weight -- basically a multivitamin with crunch.
Stage by stage
- Chewing & Release (Mouth): Chewing ruptures watercress's plant cells, letting the enzyme myrosinase convert gluconasturtiin into PEITC, the peppery compound behind watercress's signature bioactivity.
- Fat-Aided Breakdown (Stomach): In the stomach, watercress's fat-soluble vitamin K1 and beta-carotene begin mixing with any dietary fat present, since both require fat to be absorbed later.
- Absorption (Small intestine): The small intestine absorbs vitamin K1, vitamin C, folate, and PEITC into the bloodstream, with vitamin K1 uptake especially dependent on co-ingested fat.
- Activation & Use (Liver): In the liver, vitamin K1 activates clotting factors and the bone protein osteocalcin, while circulating PEITC helps induce enzymes that assist the body in clearing certain carcinogens.
Timing
Pair watercress with a source of fat -- olive oil, avocado, or eggs -- since its vitamin K1 and beta-carotene are fat-soluble and are poorly absorbed on their own.
Time to effect
- Hours to weeks: Blood levels of PEITC and vitamin K1 rise within hours of eating watercress, but effects tied to bone mineralisation or carcinogen-detoxification enzyme activity build up over weeks of regular intake.
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 September in the northern hemisphere, October to March in the southern.
Satiety
The satiety index is measured on 240 kcal servings. At 26 kcal per 100 g that is 913 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
Mid — roughly £9 per kg, as a band midpoint rather than a price.
Key nutrients
Nutrition per 100g
- Calories: 26.3
- Protein: 2.9g
- Carbohydrate: 0.8g
- of which sugars: 0.7g
- Fat: 0.4g
- of which saturated: 0g
- Fibre: 3.8g
- Sodium: 48mg
Food vs. supplement
Whole watercress delivers vitamin K1, vitamin C, and PEITC together with fiber and water, and its PEITC only forms when the plant's cells are physically broken by chewing or chopping -- a combination no isolated supplement pill reproduces.
Kitchen tip
Chop or chew watercress well rather than swallowing leaves whole -- this ruptures the plant's cells so myrosinase can convert gluconasturtiin into PEITC; light cooking is fine, but very high, prolonged heat can blunt this enzyme reaction.
Common myth
"Watercress is just a garnish -- it doesn't have any real nutritional value." In reality: Per 100 grams, raw watercress supplies about 250 micrograms of vitamin K1 (roughly 208% of the Daily Value) and 43 mg of vitamin C (about 48% DV), and it was the only food among 41 fruits and vegetables to score a perfect 100 in the CDC's 2014 nutrient-density ranking of "powerhouse" produce.
Recipes that use it
More in Vegetable
In the glossary
Sources