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Micronutrients – Major Minerals

Iron Absorption

Process of intestinal uptake of dietary iron for oxygen transport.

Definition

Iron absorption is the process by which dietary iron is taken up by intestinal cells and transported into circulation for oxygen transport and metabolic functions.

How it works

Iron exists in two dietary forms: heme iron from animal products (10-30% absorption rate) and non-heme iron from plant sources (2-20% absorption rate). Absorption occurs primarily in the duodenum and upper jejunum, with heme iron being more readily absorbed due to its direct receptor pathway. Non-heme iron absorption is highly dependent on the chemical environment; vitamin C, citric acid, and animal proteins enhance absorption, while calcium, tannins, phytates, and polyphenols inhibit it. The body regulates iron absorption through hepcidin, a hormone that increases iron absorption when stores are low and decreases it when stores are adequate. Individual factors including stomach acid, digestive health, menstrual status, and concurrent nutrient status significantly influence iron bioavailability.

Role

Iron absorption provides the iron necessary for hemoglobin formation and cellular respiration.

Examples

  • Vitamin C with meals
  • Meat consumption
  • Acidic stomach
  • Iron deficiency state
  • Avoiding tea with meals
  • Young age
  • Female menstruating

Recommendations

Pair iron-rich plant foods with vitamin C sources such as citrus, berries, or tomatoes to enhance non-heme iron absorption. Consume iron supplements on an empty stomach or with vitamin C for optimal absorption, but separated from calcium and polyphenol-rich beverages. Avoid tea and coffee with iron-rich meals, as tannins significantly inhibit iron absorption.

Key takeaway

Iron absorption efficiency depends greatly on iron type and dietary context, with vitamin C significantly enhancing non-heme iron bioavailability.

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