Iron is needed in the body to prevent iron-deficiency anaemia,
for the immune system,
for carrying oxygen throughout the body as Haemoglobin
and for helping with energy production as Cytochromes
RDA for women under 50 years of age is 18 mgr. and 10 mgr. after age 51
Iron Deficiency
Iron deficiency affects 50% women under age 45.
Rare in men
It can be caused by
menstrual loss, poor absorption,
and/or a poor diet.
Its symptoms are
fatigue,
cold hands and feet
loss of appetite,
increased irritability,
poor quality fingernails, headaches, and paleness.
Haemoglobin.
is the most abundant iron compoundin the body
It is the carrier of oxygen in the blood.
The body contains 0.750 Kg of haemoglobin and this is replaced every 3
months
Normal turnover requires 6-8 grams of new haemoglobin daily
Cytochromes & Catalase.
Cytochromes
Are present in the mitochondria and in the endoplasmic reticulum.
They participate in ATP synthesis as part of the Electron transport system
Half of them are replaced 132 hours.
Catalase and peroxidase remove hydrogen
peroxide.
Protect the body against oxidation by peroxide.
Half of these are replaced every 20 hours.
Iron in the Body
A most men contain about 3.7 grams of iron each.
Most of this, (70%) is present in haemoglobin.
Some (28%) is stored as ferritin.
The remainder is in
myoglobin,
the cytochromes,
other haemoproteins, etc.
There is no mechanism for excreting excesses iron that accumulates in the
body.
Chemical activity of Iron.
Binds non-specifically to many proteins and destroys their structures.
Acts catalytically in oxidation of unsaturated lipids in cellular membranes.
Because of this it is always found in bound form.
There is very little free iron in blood plasma
This stops bacteria growing in blood.
Because it is bound iron is NOT get excreted.
Loss of Iron from the body:
Only by:
bleeding
sloughing off of cells (lining of gut)
menstrual flow
transfer to a developing fetus.
Regulation of The body's iron content is only by controlling
absorption.
How to Increasing Iron Uptake
Eat lean meat, skinless poultry, and fish
high in absorbable iron.
Meat fish and poultry effect
increases uptake from other sources
Vitamin C-rich fruits and vegetables
It can almost double absorption.
Eat lactose-containing food.
Avoid tea and coffee 1 hr. before or 2 hr after meals
Tannin decreases iron absorption up to one-third.
Iron metabolism disorders:
Iron deficiency and iron overload diseases:
Afflict more than a billion people worldwide.
Iron overload,
Haemochromatosis is the most common human genetic disorder
Affecting up to 1 in 200 Caucasian Americans,
Causes diabetes, impotence, arrhythmia and liver failure
Absorption Control
Is done in the intestinal mucosal cells
These cells make an iron-binding protein, apoferritin.
When blood iron is low:
little apoferritin is made
This allows iron to passes through the cells freely into the plasma.
When blood iron is high
more apoferritin is made.
This apoferritin traps iron the cells as ferritin;
Bound iron is lost into the intestine with dead cells and no absorption
occurs
Oxidation changes during digestion
and absorption.
In the stomach.
Iron III (Fe+++) is reduced to iron II (Fe++).
the low pH & Reducing agents,
such as ascorbic acid & lactose
iron (II) freed from complexes
In the duodenum.
An alkaline environment
Haem is absorbed directly by the mucosal cells.
Free iron (II) ions are oxidised to iron (III)
taken up by the mucosal cells.
Dietary Iron
There are two major forms of dietary iron.
Haem iron,
found primarily in red meats, is the most easily absorbed form.
Other forms of iron are tightly bound .
Cooking increase iron availability.
In some iron-rich foods it is non-absorbable.
eg spinach. Has oxalate, -->> non-absorbable.
Phytates, present in unleavened bread
Iron Transport
Iron that is stored in intestinal mucosal cells or in the liver may be
transferred into the blood for transport to other tissues.
The iron (III) storage form must be reduced to iron (II) in order to cross
the plasma membrane.
In the blood, iron (II) is reoxidised to iron (III) by ferroxidase II.
Iron Transport in Blood
Iron (III) is carried by the serum protein, transferrin.
Normally.
transferrin is only about 1/3 saturated
An increased of iron can be handled easily.
The iron binding capacity of serum is almost entirely provided by transferrin.
Iron Storage
Ferritin is main storage compound
Mostly in the liver,
Hemosiderin
If ferritin is saturated, iron forms hemosiderin
hemosiderin is deposited in the liver and heart.
Their function can be damaged
can causes death.
Cause of Excess Body Iron.
Idiopathic hemochromatosis
excess iron is absorption.
Multiple transfusions
beta-thalassemia, needs haem supplied by blood transfusion
Treatment of Excess Iron Storage
Involves artificial removal of iron from the body.
Bleeding is the treatment of choice for idiopathic hemochromatosis.
Blood donation
Bleeding is No good for beta-thalassemia
chelators are administered which bind iron.
Chelated iron is excreted in the urine.
The End
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