There are dietary practices which affect iron absorption. For example, tea, probably on
its tannin, decreases the iron absorption from food. On he other hand some people eat more
than others and this increases the absorption of iron, even from plant foods. Various nutrition
surveys show that the quantities of both beverages and meat consumed by men and women
Alcoholic beverages, either because of the iron they contain or as an effect of alcohol itself,
increase iron absorption and thus can contribute to differences in iron needs between the
Iron absorption is altered by some other foods as well.
Iron metabolism is probably much the same between the sexes, allowing for body size. Losses through skin and gut are about 14 micrograms (0.014 milligrams) per kilogram of body weight per day - this is about one milligram in a 70 kilogram man and 0.8 milligrams in a 55 kilogram woman. Menstrual loss is the biggest distinguishing factor in iron requirements between the sexes. The menstrual loss of iron in one woman is relatively constant but varies considerably between women. It averages 09 milligram per day, but in 10 per cent of women it is greater than 2.2 milligrams per day. In general women in the reproductive phase of life do need more iron than men and therefore the current RDI (see appendix 2) for iron for Australian men
is 7 milligrams and for women is 5 to 16 milligrams per day.
Bleeding through injury or disease increases the need for iron in both sexes. In such
circumstances, the mechanism for iron absorption adjusts so that relatively more of the iron in
food and drink is absorbed.
Iron is needed for haemoglobin in red blood cells, myoglobin in muscle and for respiratory
enzymes (cytochromes) inside all body cells. Iron is also stored in liver, spleen and bone
As an example, the amount of iron in different forms in a 70 kg man is distributed as shown:
|IRON IN DIFFERENT FORMS||
haemoglobin (blood pigment)
myoglobin (muscle pigment)
iron in the process of transport around the body (as transferrin)
The total iron requirements during pregnancy amount to about 1000 milligrams, so that the better a woman's iron stores before pregnancy, the more certain it is that this requirement will be met. During lactation no menstrual iron loss usually occurs, but about 0.25 milligram iron per day goes into breast milk. Some breast-feeding women who eat well do not need iron supplements.