Everything about Iron totally explained
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For other uses, see Iron (disambiguation).
Nutrition and dietary sources
Good sources of dietary iron include
red meat,
fish,
poultry,
lentils,
beans,
leaf vegetables,
tofu,
chickpeas,
black-eyed peas, potatoes with skin, bread made from completely whole-grain flour,
molasses,
teff and
farina. Iron in meat is more easily absorbed than iron in vegetables, but
heme/
hemoglobin from
red meat increases the likelihood of
colorectal cancer.
Iron provided by
dietary supplements is often found as
iron (II) fumarate, although iron sulfate is cheaper and is absorbed equally well. Elemental iron, despite being absorbed to a much smaller extent (stomach acid is sufficient to convert some of it to ferrous iron), is often added to foods such as breakfast cereals or "enriched" wheat flour (where it's listed as "reduced iron" in the list of ingredients). Iron is most available to the body when
chelated to amino acids - iron in this form is ten to fifteen times more bioavailable than any other, and is also available for use as a common
iron supplement. Often the amino acid chosen for this purpose is the cheapest and most common amino acid, glycine, leading to "iron glycinate" supplements. The
RDA for iron varies considerably based on age, gender, and source of dietary iron (
heme-based iron has higher
bioavailability). Infants will require iron supplements if they're not breast-fed.
Blood donors are at special risk of low iron levels and are often advised to supplement their iron intake.
Regulation of iron uptake
Excessive iron can be toxic, because free ferrous iron reacts with
peroxides to produce
free radicals, which are highly reactive and can damage
DNA,
proteins,
lipids, and other cellular components. Thus, iron toxicity occurs when there's free iron in the cell, which generally occurs when iron levels exceed the capacity of
transferrin to bind the iron.
Iron uptake is tightly regulated by the human body, which has no regulated physiological means of excreting iron. Only small amounts of iron are lost daily due to mucosal and skin epithelial cell sloughing, so control of iron levels is mostly by regulating uptake. However, large amounts of ingested iron can cause excessive levels of iron in the blood because high iron levels can damage the cells of the
gastrointestinal tract, preventing them from regulating iron absorption. High blood concentrations of iron damage cells in the
heart,
liver and elsewhere, which can cause serious problems, including long-term organ damage and even death.
Humans experience iron toxicity above 20 milligrams of iron for every
kilogram of mass, and 60 milligrams per kilogram is a
lethal dose. Over-consumption of iron, often the result of children eating large quantities of
ferrous sulfate tablets intended for adult consumption, is one of the most common toxicological causes of death in children under six.
The medical management of iron toxicity is complex, and can include use of a specific
chelating agent called
deferoxamine to bind and expel excess iron from the body.
Further Information
Get more info on 'Iron'.
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