Food and nutrition.pdf

Function of Food 107with need. Menstrual loss of iron has been estimated to average a littleless than 1 mg per day during an entire year. It is recommended thatwomen of child-bearing age have a dietary intake of 18 mg per day.During pregnancy, the body requires on average about 1.5 mg of irondaily to develop the foetus and supportive tissues and to expand thematernal blood supply. Most of this additional iron is required in thesecond and third trimesters of pregnancy.Breastfeeding women use iron to provide the approximately 2 mg ofiron per litre of breastmilk. However, during the first six to 15 months ofintensive breastfeeding they may not menstruate, so they do not lose ironin menstrual blood.Newborn infants are born with very high haemoglobin levels (a highred blood cell count), termed polycythaemia, which provides an extra storeof iron. This iron, together with that present in breastmilk, is usuallysufficient for the first four to six months of life, after which iron from otherfoods becomes necessary.Premature and other low-birth-weight infants may have lower ironstores and be at greater risk than other infants.An excess intake of iron over long periods can lead to the diseasesiderosis or haemachromatosis. This disease is reported to occur mostcommonly where beer or other alcoholic beverages are brewed in ironcooking pots, particularly in South Africa. In alcoholics siderosis leadingto iron deposits in the liver may be associated with cirrhosis.Average safe levels of iron intake are provided in Annex 1.Deficiency StatesConsideration of the iron requirements and the iron content ofcommonly eaten foods might suggest that iron deficiency is rare, but thisis not the case. Food iron is poorly absorbed. Iron is not readily excretedinto the urine or the gastro-intestinal tract; thus severe iron deficiency isusually associated with an increased need for iron resulting fromconditions such as pregnancy, blood loss or expansion of the total bodymass during growth. Iron deficiency is most common in young children,in women of child-bearing age and in persons with chronic blood loss.The end result of iron deficiency is anaemia.Hookworm infections, which are extremely prevalent in manycountries, result in loss of blood which may cause iron deficiency anaemia.In some parts of the tropics schistosomiasis is also common, and thisdisease also causes blood loss.IodineThe body of an average adult contains about 20 to 50 mg of iodine,