Iron requirements also tend to be difficult tomeet, and replenishment remains challenging forthose severely deficient. Low bioavailability ofiron in cereal- and tuber-based diets is one of themain causes of iron deficiency anemia in lowincome countries, as they contain high amounts ofpolyphenols (tannins) and phytates that inhibitiron absorption. A number of practical actions andinterventions that can reduce these effects are presented below.A number of potential dietary sources need tobe urgently promoted including many leafy vegetables and legumes that contain important quantities of iron, with special emphasis on increasingthe consumption of animal products that are highin bioavailable iron and in iron absorptionenhancers. In Kenya, a study showed that meatintake in children under 3 years of age was positively related to hemoglobin, suggesting low meatintakes are an important cause of anemia in thisage group (11).The addition of small quantities of particularfoods to a cereal- or tuber-based diet increases thenutrient density considerably. The addition oflegumes can slightly improve the iron content ofcereal- and tuber-based diets. However, thebioavailability of this non-heme iron source islow. Therefore, it is not possible to meet the recommended levels of iron from staple-based dietsunless some meat, poultry, or fish is included.Adding 50 g of meat, poultry, or fish increasestotal iron content as well as the amount ofbioavailable iron. Variations in bioavailability ofiron (mg/1000 kcal) with meal composition foreach of the four basic staple diets of white rice,corn tortilla, refined couscous, and potato havebeen calculated and are presented in Table 21.2.Under ideal conditions of food access andavailability, food diversity should satisfy micronutrient and energy needs of the general population. Unfortunately, for many people in the world,access to a variety of micronutrient rich foods isnot possible. As demonstrated in the analysis oftypical staple-based diets, micronutrient richfoods including small amount of flesh foods and avariety of plant foods (vegetables and fruits) areneeded daily. This may not be realistic at presentfor many communities living under conditions ofpoverty. Food fortification and food supplementation are important alternatives that complementfood-based approaches to satisfy the nutritionalneeds of people in developing and developedcountries.Poor monotonous diets deficient in one micronutrient are also likely to be deficient in othermicronutrients, as well as in other importantfoods such as fat and protein that further reduceabsorption of what nutrients have been ingested,and of energy.Population groups consuming suchdiets are known to have multiple micronutrientdeficiencies.At the same time, increasing the consumptionof a greater variety of plant foods, especially offruits and vegetables, will provide most of themissing vitamins and minerals. In addition, anumber of plant-based nutrients or phytochemicals will be consumed and there is emerging evidence on the health benefits from food phytochemicals. This double benefit of consuming avariety of foods could play a major role in offsetting what is called the double burden of malnutrition.
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