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BIOCHEMICALLY IMPORTANT MINERAL ELEMENTS 



distributed in both plant and animal cells, and in the various lower forms 

 of life, where they are concerned with biological oxidation processes (see 

 Chap. 13). A good daily allowance of iron for human beings has been 

 estimated by the Food and Nutrition Board to be as follows: normal 

 adult, 12 mg.; woman during pregnancy and lactation, 15 mg.; infants, 

 6 mg.; children 1 to 12 years old, 7 to 12 mg.; and adolescents 13 to 15 

 years old, 15 mg. The need for iron is, of course, greatest whenever 

 hemoglobin is being formed in the body in relatively large amounts, as 

 during rapid growth and after the loss of blood. For this reason women 

 should have more iron than men to compensate for blood lost during 

 menstruation. In fact, there is evidence that adult men, and women 

 after the menopause, get along quite satisfactorily even when they receive 

 much less than the above amounts of iron. 



An adequate copper intake is provided by an amount equal to about 

 one-tenth that of iron. For adults, this is in the range of 1 to 2 mg. per 

 day. A good diet containing enough of the other essential food factors 

 may be depended upon to contain sufficient copper, except in a few areas 

 where the copper content of the soil is abnormally low. Such copper- 

 deficient areas have been reported in Holland, Florida, New Zealand, 

 and parts of Great Britain and Australia. 



Iron, on the other hand, is one of the mineral elements which is apt to 

 be supplied in too small amounts by ordinary dietaries. This is partly 

 due to the modern process of refining cereals, which removes much of 

 the iron (see Table 8-1 ) , and partly to the fact that the iron contained 

 in many foods is not well assimilated by the body. Thus the iron in 

 the iron-porphyrin substances listed above is not utilized, although most 

 simple, inorganic iron salts, and even metallic iron itself if finely divided, 

 are able to meet bodily needs very well. It is important, therefore, to 

 consider not only the total iron content of various foods, but also the 

 proportion of it which is physiologically available. The best food sources 

 of iron are liver and egg yolk. Muscle meats, fish, green leafy vegetables, 

 and dried peas and beans are also good sources, since they are high in 

 total iron, and about half of it is available. White flour is low in iron, 

 but is now being enriched approximately to whole grain levels so that 

 it probably contributes materially to the total intake. Milk is deficient 

 not only in iron, but also in copper and manganese. 



Cobalt. That cobalt also plays a role in hemoglobin formation is 

 evidenced by the fact that cattle and sheep in certain areas of New 

 Zealand, Australia, and Florida sometimes suffer from a nutritional 

 anemia that can be cured only by administration of small amounts of 

 this element. Cobalt deficient areas have also been reported in Wisconsin, 

 Michigan, New Hampshire, North Carolina, Great Britain, and Scotland. 

 The occurrence of deficiency symptoms is limited to cows, sheep, and 

 other ruminants. Feeding trials with cobalt-low rations have failed to 



