Watercress Nutrition Calculator — Calories & Nutrition per Serving

In a 2014 CDC-published study classifying 41 'powerhouse fruits and vegetables' by nutrient density, watercress scored a perfect 100 out of 100 — the highest of any food analyzed. The ranking was based on mean percentages of daily values across 17 qualifying nutrients per 100 kcal. Watercress's extreme low calorie count (11 kcal per 100g) and high micronutrient concentration produced the top score ^[2].

The numbers behind this ranking: per 100g raw, watercress delivers 250mcg vitamin K (208% DV), 43mg vitamin C (48% DV), 160mcg vitamin A RAE (18% DV), and 120mg calcium (9% DV) — all at just 11 calories. Per calorie, this is the most micronutrient-dense profile available from a common vegetable ^[1].

For nutrition logging, this means even small amounts of watercress add meaningful micronutrient contributions: one cup chopped (~34g) provides 85mcg vitamin K (71% DV) and 14.6mg vitamin C (16% DV) at just 4 calories. As a garnish or salad base, watercress adds micronutrient value with essentially zero caloric impact ^[1].

Watercress provides 250mcg of vitamin K (phylloquinone) per 100g — exceeding the daily value by more than 2x in a single 100g serving. Among common leafy greens, only spinach (483mcg) and kale (~390mcg) deliver more vitamin K per 100g. But when adjusted for calories, watercress delivers 22.7mcg vitamin K per calorie — far exceeding spinach (21mcg/kcal) and kale (11.1mcg/kcal) ^[1].

Vitamin C at 43mg per 100g (48% DV) is remarkably high for a leafy green. Spinach has 28.1mg, romaine lettuce has 4mg, and arugula has 15mg. One bunch of watercress (~80g) provides 34.4mg vitamin C (38% DV) at just 9 calories — making watercress an effective low-calorie source of this heat-sensitive vitamin ^[1].

Vitamin A at 160mcg RAE (18% DV) comes from 1,914mcg beta-carotene and 5,767mcg lutein + zeaxanthin — a substantial carotenoid concentration for a leafy green. While spinach (~12,198mcg) and kale (~6,260mcg) have higher lutein + zeaxanthin totals, watercress delivers more per calorie due to its extremely low 11 kcal count. These fat-soluble carotenoids are better absorbed when consumed with a small amount of dietary fat ^[2].

Watercress contains 120mg calcium per 100g — matching whole milk (113-125mg per 100ml depending on source) in calcium content. While 100g of watercress is a larger volume than 100ml of milk (watercress is 95.1% water and very light), the calcium bioavailability from cruciferous greens like watercress is estimated at 40-65%, compared to approximately 30-32% from milk ^[1][3].

Phosphorus at 60mg supports calcium metabolism, while magnesium at 21mg and potassium at 330mg (7% DV) round out the mineral profile. The potassium content is notable — higher per 100g than many fruits including apple (107mg) and grape (191mg), though practical intake depends on serving size since watercress is typically consumed in smaller quantities ^[1].

The calcium-to-calorie ratio is extraordinary: 10.9mg calcium per calorie. For comparison, whole milk provides approximately 1.85mg calcium per calorie, kale provides 7.3mg per calorie, and arugula provides 6.4mg per calorie. For calorie-conscious calcium tracking, watercress is one of the most efficient whole-food sources available ^[1].

At 2.3g protein per 100g, watercress doesn't look like a significant protein source. But at only 11 calories, the math is striking: protein provides 9.2 of those 11 calories (84%). This is the highest protein-to-calorie ratio among common vegetables — higher than spinach (49%), broccoli (33%), or asparagus (44%) ^[1].

In practical terms, you would need to eat an unrealistic amount of watercress (~4.3kg) to get 100g of protein. The statistic is more useful for understanding watercress's role in calorie-efficient meal composition: adding watercress to a plate increases the protein proportion of the overall meal while adding virtually zero caloric dilution ^[1].

The amino acid profile includes notable amounts of threonine (0.13g, 10% DV per 100g), tryptophan (0.03g, 9% DV), and valine (0.14g, 9% DV) relative to serving size. While individual amino acid contributions from watercress are small, the overall quality is high for a plant food — the protein is not limiting in any single essential amino acid ^[1].

All three are nutrient-dense leafy greens, but the profiles differ meaningfully. Watercress wins per-calorie: at 11 kcal, its vitamin K (22.7mcg/kcal) and vitamin C (3.9mg/kcal) densities are unmatched. Kale wins on total vitamin C (93.4mg vs. 43mg) and calcium (254mg vs. 120mg), but at 3x the calories (35 kcal). Spinach wins on total vitamin K (483mcg) and vitamin A (469mcg RAE) ^[1].

Iron tells a surprising story: watercress has only 0.2mg per 100g — far less than spinach (2.71mg) or kale (1.6mg). Despite its overall nutrient density, iron is watercress's weakest mineral. This is relevant for logging: if iron intake is a priority, spinach or kale are significantly better choices ^[1].

Fiber is minimal in watercress (0.5g per 100g) compared to kale (4.1g) and spinach (2.2g). Watercress is fundamentally a micronutrient vehicle, not a fiber or macronutrient source. Its role in a balanced diet is to concentrate vitamins K, C, and A into the lowest possible calorie budget — it fills a different niche than heartier greens ^[2].