Minerals- Iron

Question 1

What is the main function of iron in the body?

Answer 1

Oxygen transport in haemoglobin and myoglobin
In cytochromes
DNA synthesis
collagen synthesis
conversion to tyrosine

Question 2

How much iron is taken in and lost in the body? How much is recycled?

Answer 2

1-2mg lost and gained. 25mg recycled
Iron is recycled, only real way to lose copious amounts of iron is through blood loss.
RBC turnover is high so when RBC dies, iron is recycled

Question 3

How is iron recycled?

Answer 3

1) bone marrow incorporates iron into RBCs
2) RBCs are dismantled in the liver, where iron is transferred on to transferrin to go around the body or ferritin to be stored
3) Some iron is lost in sweat, urine, but transferrin carries iron round the body to bone marrrow, Some iron is taken to muscles for myoglobin.

Question 4

How is iron absorbed?

Answer 4

Absorbed in the duodenum, if the body needs iron, is stored in mucoal ferritin, and is handed to mucosal transferrin then transferrin if need be.
If the body does need need iron, stored in mucosal ferritin and the is lost when the mucosa sheds

Question 5

How are the different forms of ingested iron taken up by gut enterocytes?

How is non haem iron reduced and absorbed?

Are there any receptors on the surface facing plasam?

Answer 5

Haem iron (meat) is taken up easily, and haem oxygenase converts it to Fe2+, stored in the labile iron pool and lost to plasma by a IReg1 protein (ferroportin), or stored as ferritin

Non haem iron is reduced by stomach acid and dietary reducing agents. Also cytochrome enzymes on cell. Transported in by DMT-1

Transferrin receptors on plasma surface

Question 6

What regulates cells taking up iron?

Answer 6

Transferrin receptors cause iron to be taken into hepatocyte
When RBC broken down, macopahge ingests iron and ferroportin puts iron onto transferrin?
Master regulator is hepcidin (hormone in liver, haemochromatosis affects this, over storage in liver)

Question 7

What factors enhance no heme iron absorption?

Answer 7

vitamin C; MFP factor; citric and lactic acid

Question 8

What inhibits non heme iron absorption?

Answer 8

tannins, phytates, fibres, calcium, oxalates

Question 9

What are the three stages of iron deficiency?

Answer 9

1. depleted iron storage- low serum ferritin
2. Iron restricted erythropoiesis, low serum transferrin saturation
3. iron deficiency anaemia- low haemoglobin

Question 10

What people often have low iron?

Answer 10

vegetarians, pregnant women, elite female athletes