Iron: the deficiency a food log actually catches

Iron deficiency is the most common nutritional deficiency in the world, and it is quietly common in wealthy countries too, particularly in menstruating women, endurance athletes, vegetarians, and anyone who has recently donated blood.

The symptoms are unhelpfully ordinary: tired, cold, short of breath on stairs, foggy. Which describes most people's Tuesday.

The targets

That last multiplier is not a rounding, it reflects a real difference in how the iron is absorbed.

Two kinds of iron, absorbed very differently

Heme iron comes from animal flesh, red meat, poultry, fish. Absorbed at roughly 15–35%: and relatively unbothered by what else is on the plate.

Non-heme iron comes from plants, eggs and fortified grains. Absorbed at roughly 2–20%: and that tenfold range depends almost entirely on what you eat it with.

This is why the milligrams on a label understate the situation for plant sources. A cup of spinach lists 6 mg and delivers a fraction of it.

What moves absorption

Up: - Vitamin C in the same meal. The biggest single lever; it can multiply non-heme absorption several times over. Lemon on lentils, peppers in a bean chili, an orange with fortified cereal. - A little meat alongside plants. Improves absorption of the plant iron in the same meal. - Cast iron cookware. Genuinely transfers iron into acidic foods.

Down: - Tea and coffee. Tannins bind iron. A cup with a meal can cut absorption substantially, move it to an hour either side. - Calcium. Competes directly. Iron and dairy in the same sitting is a poor pairing. - Phytates in whole grains and legumes. Soaking, sprouting and fermenting reduce them.

A worked example

Lentils with lemon and peppers, no tea: good iron meal.

The same lentils with a glass of milk and a cup of tea: the same milligram figure on paper, a fraction of the iron delivered.

No food database captures this, because the interaction is between foods rather than inside one.

Do not supplement on a hunch

Iron is one of the few nutrients where more is actively risky. The body has no efficient route to excrete excess, and overload damages the liver and heart, and hereditary hemochromatosis is more common than most people assume.

Test before supplementing. Ferritin plus a full blood count. If you are tired, the answer might be iron, and it might be sleep, thyroid, or B12, and guessing wrong costs you months.

Tracking iron intake tells you whether a deficiency is plausible from diet, which is a useful thing to bring to a blood test. It does not tell you your iron status, and nothing you can photograph will.