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Essential mineral

Iron

Iron is part of proteins that carry oxygen in the blood and make it available in muscles. The body needs that oxygen for normal cell activity.

Read Iron in the Atlas explorer, with its charts

Measured in mg · Daily Value 18 mg

What it does, and how

  • Carry oxygen from the lungs to tissues

    Hemoglobin is the oxygen-carrying protein in red blood cells. Iron is part of hemoglobin, allowing the blood to transport oxygen around the body.

    Hemoglobin and oxygen transport · Evidence

    Iron is a component of oxygen-transporting hemoglobin.

    Normal physiological role only; does not establish an effect of eating Kale.

    • Read sourceIntroduction: hemoglobin, myoglobin, heme/nonheme paragraphs

    Sources for the explanation

  • Make oxygen available inside muscle

    Myoglobin is an iron-containing protein in muscle. It binds oxygen and helps make it available within muscle tissue, supporting normal muscle metabolism.

    Myoglobin and muscle oxygen · Evidence

    Iron is a component of myoglobin involved in muscle oxygen provision.

    Normal physiological role only; does not establish an effect of eating Kale.

    • Read sourceIntroduction: hemoglobin, myoglobin, heme/nonheme paragraphs

    Sources for the explanation

Where it works in the body

A nutrient can take part in more than one body system. Follow a connection to see how its work fits together with other nutrients.

The body map groups established nutrient roles to help you explore; it does not predict a health outcome from eating a food. Evidence and mapping notes.

How does the body keep a supply? Learn about nutrient storage, depletion and replenishment.

Reference food in our crop catalog

Reference composition

Basis: raw edible food, per 100 g. % DV uses FDA Daily Values for adults and children 4+ where one exists; values above 100% are shown without capping. Reference amounts describe the USDA food, not a UCFarms harvest. “No DV” means there is no applicable Daily Value or conversion.

Sources & references (11)
  1. Spinach, raw, USDA FoodData Central 168462 · U.S. Department of AgricultureReference databaseSelected nutrient amounts per 100 g raw edible spinach. Reference food, not a UCFarms harvest measurement.Source details in the Atlas: Spinach, raw, USDA FoodData Central 168462Verified from the official SR Legacy JSON download. The exact food record and source calculation are available in the crop reference profiles below.https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_sr_legacy_food_json_2018-04.zip
  2. Collards, raw, USDA FoodData Central 170406 · U.S. Department of AgricultureReference databaseSelected nutrient amounts per 100 g raw edible collard greens. Reference food, not a UCFarms harvest measurement.Source details in the Atlas: Collards, raw, USDA FoodData Central 170406Verified from the official SR Legacy JSON download. The exact food record and source calculation are available in the crop reference profiles below.https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_sr_legacy_food_json_2018-04.zip
  3. Watercress, raw, USDA FoodData Central 170068 · U.S. Department of AgricultureReference databaseSelected nutrient amounts per 100 g raw edible watercress. Reference food, not a UCFarms harvest measurement.Source details in the Atlas: Watercress, raw, USDA FoodData Central 170068Verified from the official SR Legacy JSON download. The exact food record and source calculation are available in the crop reference profiles below.https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_sr_legacy_food_json_2018-04.zip
  4. Basil, fresh, USDA FoodData Central 172232 · U.S. Department of AgricultureReference databaseSelected nutrient amounts per 100 g raw edible basil. Reference food, not a UCFarms harvest measurement.Source details in the Atlas: Basil, fresh, USDA FoodData Central 172232Verified from the official SR Legacy JSON download. The exact food record and source calculation are available in the crop reference profiles below.https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_sr_legacy_food_json_2018-04.zip
  5. Strawberries, raw, USDA FoodData Central 167762 · U.S. Department of AgricultureReference databaseSelected nutrient amounts per 100 g raw edible strawberries. Reference food, not a UCFarms harvest measurement.Source details in the Atlas: Strawberries, raw, USDA FoodData Central 167762Verified from the official SR Legacy JSON download. The exact food record and source calculation are available in the crop reference profiles below.https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_sr_legacy_food_json_2018-04.zip
  6. Mushrooms, oyster, raw, USDA FoodData Central 168580 · U.S. Department of AgricultureReference databaseSelected nutrient amounts per 100 g raw edible oyster mushroom. Reference food, not a UCFarms harvest measurement.Source details in the Atlas: Mushrooms, oyster, raw, USDA FoodData Central 168580Verified from the official SR Legacy JSON download. The exact food record and source calculation are available in the crop reference profiles below.https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_sr_legacy_food_json_2018-04.zip
  7. Kale, raw: FoodData Central 323505 · USDA Agricultural Research ServiceReference databaseReference nutrient composition of raw kale, per 100 g edible portion.Source details in the Atlas: Kale, raw: FoodData Central 323505The audit used USDA’s Foundation Foods download. If this record link is unavailable, use the dataset or saved record below.https://fdc.nal.usda.gov/food-details/323505/nutrients
  8. Daily Value on the Nutrition and Supplement Facts Labels · U.S. Food and Drug AdministrationGovernmentFDA Daily Values (adults and children 4+) used to compute % DV.Source details in the Atlas: Daily Value on the Nutrition and Supplement Facts Labelshttps://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels
  9. Iron: Fact Sheet for Health Professionals · National Institutes of Health, Office of Dietary SupplementsGovernmentIron's role in hemoglobin and myoglobin oxygen transport.Source details in the Atlas: Iron: Fact Sheet for Health Professionalshttps://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
  10. Foundation Foods JSON release 2026-04-30 · USDA Agricultural Research ServiceReference databaseSource details in the Atlas: Foundation Foods JSON release 2026-04-30https://fdc.nal.usda.gov/fdc-datasets/FoodData_Central_foundation_food_json_2026-04-30.zip
  11. Foundation Foods Documentation · USDA Agricultural Research ServiceReference databaseSource details in the Atlas: Foundation Foods Documentationhttps://fdc.nal.usda.gov/Foundation_Foods_Documentation/

The nutrition and biological information on this site is provided for educational purposes and is not a substitute for individualized medical advice.