Iron is one of 14 essential trace elements present in hormones, vitamins, enzymes and other proteins which have distinct biological role. In addition, numerous other elements occur in the human body and their physiological roles have not yet been determined.
A deficiency in the essential trace elements results in metabolic disorders that are primarily associated with the absence or decreased activity of metabolic enzymes.
The iron content of the body is 4-5 g. Most is present in the hemoglobin (blood) and myoglobin (muscle tissue) pigments. The metal is also present in a number of enzymes, hence it is an essential ingredient of the daily diet.
The iron requirement depends on the age and sex of the individual, but it is about 1-2.8 mg/day. Iron supplied in the diet must be in the range of 5-28 mg/day in order to meet this daily requirement.
The large variation in intake can be explained by different extents of absorption of the various forms of iron present in food (organic iron compound vs simple salts). The most utilizable source is iron in meat, for which the extent of absorption is 20-30%. The absorption is much less from liver (6.3%) and fish (5.9%), or from cereals, vegetables and milk, from which iron absorption is the lowest (1.0-1.5%). Eggs decrease and ascorbic acid increases the extent of absorption. Bran interferes with iron absorption due to the high content of phytate.
Apparently, the absorption of iron present in food is, in a healthy organism, regulated by the requirement of the organism. Nevertheless, in order to provide a sufficient supply of iron to persons who require higher amounts (children, women before menopause and pregnant or nursing women), cereals, (bread, flour, rice, pasta products) fortified with iron to the extent of 55-130 mg/kg are recommended.
Extensive feeding tests with chickens and rats have shown that FeeSO4 is the most suitable form of iron, but ferrous gluconate and ferrous glycerol phosphate are also absorbed.
Two food processing problems arising from mineral fortification are the increased probability that oxidation will occur and, in the case of wheat flour, decreased baking quality.
Generally, iron is an undesirable element in food processing; for example, iron catalyzes the the oxidation of fat or oil, increases turbidity of wine and, as a constituent of drinking water, it supports the growth of iron-requiring bacteria.
