19/10/2025
How iron, folate, and vitamin B12 sustain red blood cell formation
Iron, folate, and vitamin B12 are essential nutrients that work together to make and mature red blood cells. Their metabolism is tightly controlled because even small deficiencies can impair oxygen delivery and DNA synthesis, leading to anemia.
1️⃣ Iron intake and absorption
Most adults need 10–20 mg of dietary iron per day, but only 3–15% is absorbed in the small intestine. Iron from meat (heme iron) is absorbed more efficiently than iron from plants (non-heme iron). Stomach acid helps convert ferric iron (Fe³⁺) to its absorbable ferrous form (Fe²⁺).
🟢 Example: Vitamin C enhances absorption by reducing Fe³⁺ to Fe²⁺, while phytates in grains or excess calcium reduce uptake.
2️⃣ Iron transport and storage
Once absorbed, iron binds to transferrin, the blood’s transport protein, and is delivered to tissues like the bone marrow for red blood cell production. Surplus iron is stored in the liver as ferritin and hemosiderin. The hormone hepcidin from the liver regulates iron export—high levels block release, preventing overload.
🟢 Example: In chronic inflammation, hepcidin rises, trapping iron in macrophages and leading to “anemia of chronic disease.”
3️⃣ Iron recycling
When red blood cells break down, macrophages in the spleen and liver recover the iron from hemoglobin and return it to circulation. This recycling process supplies most of the daily iron needed for new red blood cell formation.
🟢 Example: The body recycles about 25 mg of iron each day, far exceeding the amount absorbed from food.
4️⃣ Folate and vitamin B12 absorption
Folate is absorbed in the small intestine, while vitamin B12 requires intrinsic factor from the stomach for uptake in the ileum. Both nutrients are stored in the liver and used for DNA synthesis in developing red blood cells.
🟢 Example: Vitamin B12 intake averages just 1 microgram daily, but liver stores (≈2–5 mg) can last for years, while folate stores deplete within months if intake falls.
5️⃣ Shared role in erythropoiesis and DNA synthesis
Inside bone marrow, folate and B12 cooperate to generate tetrahydrofolate, a cofactor for DNA and red cell production. Without them, cells enlarge without dividing properly, producing megaloblastic anemia.
🟢 Example: B12 deficiency traps folate in its inactive form (“methyl-folate trap”), halting DNA replication and leading to fatigue, pale skin, and neurological symptoms.
Efficient red blood cell production depends on the seamless interaction between iron supply, folate metabolism, and vitamin B12 activation. When any link in this triad breaks, oxygen transport falters and anemia develops—a sign that cellular energy and repair are being starved at the molecular level. #
