Rumex (Dock / Sorrel) Leaves Nutrition Calculator — Raw, Boiled & Sautéed

USDA data confirms dock (Rumex) leaves deliver 103mg magnesium per 100g raw (25% DV) — substantially more than spinach (79mg), Swiss chard (81mg), and kale (47mg) ^[1]. At just 22 kcal, the magnesium density reaches 4.7mg per calorie — among the highest of any food.

Boiling reduces magnesium to approximately 88mg per 100g due to mineral leaching into cooking water. A 1-cup cooked serving (133g) still provides 117mg magnesium (28% DV) — making dock one of the most efficient magnesium sources per calorie among all vegetables ^[1].

Raw dock provides 48mg vitamin C (53% DV) and 200mcg vitamin A RAE (22% DV from 4,000 IU beta-carotene) per 100g ^[1]. Boiling reduces vitamin C to 26.3mg (45% loss) and vitamin A to 174mcg (13% loss) — vitamin A being more heat-stable than vitamin C.

Sautéing retains approximately 30mg vitamin C and actually enhances vitamin A bioavailability through the added cooking fat. The characteristic sour/tart flavor of dock comes from oxalic acid — the same compound found in spinach and rhubarb ^[2].

Dock leaves deliver 2.4mg iron per 100g raw (13% DV) with 2.9g fiber (10% DV) at just 22 kcal ^[1]. The iron-to-calorie ratio of 0.11mg per calorie is comparable to spinach (0.12mg/kcal) — both are among the most iron-efficient vegetables.

Boiling slightly reduces iron to 2.08mg per 100g while fiber drops to 2.5g. The oxalic acid in dock may reduce iron absorption — pairing with vitamin C sources (which dock itself provides at 48mg raw) can partially offset this effect ^[1].

At just 4mg sodium per 100g raw, dock leaves are naturally among the lowest-sodium greens — dramatically less than beet greens (226mg), Swiss chard (213mg), and even spinach (79mg) ^[1]. For sodium-conscious meal tracking, dock adds essentially zero sodium.

Combined with 390mg potassium per 100g raw (8% DV), dock provides a 97.5:1 potassium-to-sodium ratio — one of the highest among vegetables. This makes dock particularly relevant for food journals that track sodium-potassium balance ^[1].

Per 100g raw, dock (22 kcal, 103mg Mg, 44mg Ca) differs from spinach (23 kcal, 79mg Mg, 99mg Ca) and garden sorrel (22 kcal, similar Mg) primarily in magnesium content — dock has 30% more magnesium than spinach ^[1]. Spinach has far more folate (194 vs 13mcg) and more calcium.

All three contain oxalic acid, which gives them their characteristic tartness and can bind calcium. For comprehensive green-variety journaling, dock fills the magnesium niche, spinach the folate niche, and sorrel the vitamin C niche. Note that 'dock' and 'sorrel' are both Rumex species — dock is typically R. crispus (curly dock) while sorrel is R. acetosa (garden sorrel) ^[2].