What is the role of the iron in the body and two factors that influence its absorption?

• A. Iron stores energy and its absorption is increased by caffeine.
• B. Iron is a hormone that regulates metabolism and its absorption is unaffected by vitamin C.
• C. Iron is a component of hemoglobin; absorption is inhibited by phytates and calcium and enhanced by vitamin C.
• D. Iron carries oxygen in hemoglobin; absorption increases with vitamin C and is inhibited by phytates, calcium, and tannins.

Answer: (D)

Iron's job is to carry oxygen in the blood, attached to hemoglobin in red blood cells (and to a similar protein in muscles called myoglobin). The body’s ability to absorb iron depends on its form and the other things present in the meal. Vitamin C helps iron absorption by keeping iron in a soluble, usable state and by reducing ferric iron to ferrous iron, which the intestine can take up more easily. This boosting effect is especially important for non-heme iron from plant foods.

On the flip side, several dietary components can hinder absorption. Phytates found in whole grains and legumes can bind iron, forming insoluble compounds that aren’t absorbed. Calcium—whether from dairy foods or supplements—can compete with iron for absorption. Tannins in tea and coffee can also bind iron and reduce uptake.

So, iron’s role in oxygen transport is clear, and its absorption is increased by vitamin C while being inhibited by phytates, calcium, and tannins. For best absorption, pairing vitamin C-rich foods with iron-containing meals and being mindful of consuming iron with high-phytate, calcium-rich, or tannin-containing beverages can make a difference.