Lecture #20 - Iron

Question 1

In what two oxidative states can iron be found in the human body and food?

Answer 1

Ferrous (Fe2+) and ferric (Fe3+) states.

Question 2

Where is most of the body’s iron found and what is its role?

Answer 2

About 2/3 of the body’s iron is found within red blood cells (RBCs) as part of hemoglobin, which binds and transports oxygen (O2) to tissues.

Question 3

What is the difference between heme and nonheme iron?

Answer 3

Heme iron is complexed within heme structures such as myoglobin and cytochromes of animal foods,

while nonheme iron is found in plants and plant-derived foods.

Question 4

How efficiently is nonheme iron absorbed compared to heme iron?

Answer 4

Nonheme iron is less efficiently absorbed than heme iron.

Question 5

How is heme iron absorbed in the body?

Answer 5

Heme iron must be liberated from the globin portion of hemoglobin and myoglobin, then the soluble heme, with iron bound to the porphyrin ring, is absorbed intact across the enterocyte by heme carrier protein 1 (hcp1).

Question 6

Name the factors that enhance iron absorption.

Answer 6

Vitamin C, gastric acidity, lactic and tartaric acids, meat, fish, and poultry.

Question 7

What dietary components limit iron absorption?

Answer 7

Phytates, oxalates, tannins, and calcium can reduce iron absorption by binding to it and making it insoluble.

Question 8

What is the primary transporter of iron in the blood?

Answer 8

Transferrin, which has the highest affinity for ferric iron.

Question 9

How is iron stored in the body, and where?

Answer 9

Iron is primarily stored as ferritin in the liver, bone marrow, intestine, and spleen, with hemosiderin being another storage form derived from ferritin breakdown.

Question 10

hemosiderin

Answer 10

another iron-storage protein, which is believed to derive from the breakdown of ferritin

Question 11

How is iron transported in tissues

Answer 11

In tissues, ferrous iron must be oxidized to ferric and it requires copper transport protein

Copper deficiency can cause anemia by reducing circulating ferric iron levels and its delivery to sites of erythropoiesis in bone

Question 12

List the primary functions of iron in the body.

Answer 12

1. acts as an enzyme cofactor
2. vital for oxygen transport and use
3. energy production
4. amino acid metabolism
5. synthesis of carnitine, collagen, and thyroid hormone.

It also participates in the Fenton reaction, producing free radicals.