Heme iron comes from animal muscle and blood and absorbs efficiently — roughly 15–35%. Non-heme iron from plants, grains, and legumes absorbs at a lower and more variable rate. Meat also appears to enhance absorption of the non-heme iron eaten alongside it, which is one reason mixed diets cover iron needs more easily.
Who needs more
Requirements diverge sharply by life stage: 8 mg a day for most adults, 18 mg for menstruating women, and 27 mg during pregnancy. Iron deficiency is the world's most common nutritional deficiency; fatigue and cold hands and feet are its familiar early signals.
Inhibitors and promoters
Tea and coffee with meals, and calcium supplements taken at the same time, reduce non-heme iron absorption. Vitamin C increases it. So the timing matters: drink tea between meals rather than during an iron-rich one if your levels run low.
Calcium, zinc, magnesium
Calcium at about 1,000 mg/day supports bone density, with dairy, fortified plant milks, and leafy greens as leading sources. Zinc near 8–11 mg/day supports immune function and wound healing; oysters, red meat, and seeds concentrate it. Magnesium at 310–420 mg/day participates in hundreds of enzyme reactions, with nuts, whole grains, and dark chocolate among the better food sources.
Reading mineral rankings
Mineral leaderboards often feature shellfish, organ meats, seeds, and dark leafy greens. Organ meats top iron lists because the liver stores it — nutritionally real, though portion sizes in practice are small. Compare within food groups for the most actionable reading.