Iron deficiency is the most widespread nutrition problem in the world today. According to the WHO the incidence of iron deficiency in developing countries is 26% for men, 42% for women, 46% for school-age children and 51% for children 0 to 4 years of age.6 Iron is essential for the formation of haemoglobin and shortages will lead to anaemia. Iron, together with zinc and copper is also essential for maintaining immunocompetence. Deficiencies in either of these minerals will lead to increased susceptibility to infectious illnesses.15 An early symptom of iron deficiency is chronic tiredness, whereas dizziness, breathlessness, interference with body temperature regulation and constipation are further warning signs. In infants, iron-deficiency anaemia has been shown to delay psychomotor development and impair the cognitive performance, and deficiency in mothers during pregnancy increases maternal mortality, prenatal and perinatal infant loss and premerturity.6
Iron can enter into the body in two forms, nonhaeme iron and haeme iron. All the iron in plant foods is in the form of nonhaeme iron, whereas in animal tissues three fifths of the iron is in the form of nonhaeme iron and two fifths is in the form of haeme iron. Haeme iron is more readily absorbed than nonhaeme iron, and this has prompted the concern that vegetarians may suffer from iron deficiency. The RDA for iron is 10 mg/day for men and 18 mg/day for women in their childbearing years. In a recent survey of the relevant literature it was found that adult menstruating women need to absorb 2,84 mg/day of iron and, as only a fraction of the dietary iron is absorbed, this would require a dietary intake of 18,9 mg/day. Teen-age girls would require a somewhat higher intake of 21,4 mg/day. However, many factors, such as the type of contraceptive used and the type of diet consumed, impacted on iron requirements.16
Most vegetarians living in Western countries have less iron deficiencies than might be expected from the type of iron which they consume. One of the reasons for this phenomenon is that nonhaeme iron absorption is enhanced by other factors in the vegetarian diet. Vitamin C intake in vegetarians is normally high, and this enhances the uptake of iron, and can counteract the effect of absorption inhibitors such as phytate which acts as a chelator of iron. The mineral content of plant foods is often high, and this can also offset the effects of inhibitors. Black tea also contains high concentrations of inhibitors, which impact negatively on iron absorption and avoidance of this beverage is thus advisable. A further factor which can lead to inadequate iron absorption is a high calcium level in the diet.17 Finally it can be said that a vegetarian whole-food diet can supply all the iron requirements, provided a varied diet is followed, which includes a regular consumption of iron-rich foods as outlined in chapter 7.