Anemia refers to a condition in which the hemoglobin content of the blood is lower than normal as a result of a deficiency of one or more essential nutrients [1], heavy blood loss, parasitic infections such as hookworm infestations, acute and chronic [2] infections, and congenital hemolytic diseases [2–5]. At least half of anemia worldwide is due to iron deficiency [6]. Iron deficiency is due primarily to a lack of bio-available dietary iron [7, 8] or increased requirements such as during childhood and pregnancy [2]. Anemia increases risk for maternal and child mortality and has negative consequences on the cognitive and physical development of children, and on work productivity in adults [2]. Clinical signs of anemia include breathlessness, dizziness, and perceived paleness or change of skin color [9]. Because of the economic, social, and other negative consequences, anemia is a priority nutritional problem in most of the developing world [2, 10–12].

The World Health Organization (WHO) estimates that the highest proportion of individuals affected by anemia are in Africa and that in Ethiopia anemia is a severe problem for both pregnant (62.7%: 95% CI 30.1-86.7) and non-pregnant women of childbearing age (52.3%: 95% CI 24.9-78.4) [2]. A few reports among the rural and urban communities in Ethiopia recognize anemia, particularly iron deficiency anemia, as a moderate public health problem in the country [13–17]. However, despite some available evidence [15, 16, 18–22], iron deficiency anemia was documented as a rarity in Ethiopia by some investigators who based their conclusion on small samples [23–25]. These investigators suggested that because of exposure to high iron intake [24, 25] combined with hypoxia due to high altitude [24] and infestations with intestinal parasites or other illness [23] anemia was not due to malnutrition. The idea of the problem being rare persists among some researchers despite the age of the previous research and provides motivation for this study.

Given the fact that Ethiopia is among the poorest country in Africa with high rates of food insecurity and malnutrition [26, 27] one may assume problems with iron deficiency anemia. Although Ethiopia has a wide range of agro-climatic conditions and grows a variety of cereals, root crops and vegetables, some of these are not fully utilized. There appears to be dependency on a single food crop by region although the specific crop varies in the different regions. The staple crops consumed in the North and Central part of Ethiopia are teff (Eragrostis tef) and cereals; in the South and Southwest staple crops are enset (Ensete ventricosum), cassava (Manihot esculenta), maize (Zea mays), cereals and root crops; and in the East staple crops are sorghum and maize. The lack of dietary diversity results in a shortage of minerals and vitamins which suggests that the bio-availability of much of the iron in the average Ethiopian diet is restricted and this restriction presumably affects the iron status [13]. The purpose of this study was to determine the prevalence of anemia, iron deficiency, and iron deficiency anemia in Ethiopian women of childbearing age using a large sample of the population.

The criteria for determining the presence of anemia, as recommended by the World Health Organization (WHO), are based on hemoglobin cut-off values for age and sex with an additional epidemiological criterion for assessing the severity and magnitude of the problem in populations [1, 2, 6, 7]. Ideally, prevalence studies should be based on a representative sample composed of every segment of population but when this is not feasible, the prevalence in high-risk group could be a valid indication for the magnitude of the problem [5]. Based on such premises, in Ethiopia a few studies with small sample size conducted at different times documented the existence [9, 13–22, 33] of iron deficiency anemia while other studies reported it as being rare in the country [23–25] despite the fact that iron deficiency anemia remains a widespread public health problem in most developing countries and even developed countries, a considerable number of women tend to have inadequate reserve to meet the requirement of pregnancy. [34]

Estimates of iron deficiency anemia (IDA) in our study, 18.0%, were based on two measures, hemoglobin and serum ferritin, and indicate a moderate public health problem according to WHO standards [7]. This is similar to a prevalence of IDA of 22.3% in a group of 197 lactating women in Addis Ababa, Ethiopia [18] and 18.4% in a group of 1134 pregnant and lactating women in Ethiopia [35] based on these same measures. Additionally prevalence of anemia was 15.1% based on low hemoglobin in a cross-sectional survey of 403 pregnant women attending an urban health centre in Awassa, (Southern Ethiopia) [9], and 13% of a group of 99 women in late pregnancy from Sidama (Southern Ethiopia) based on mean cell hemoglobin concentrations and mean corpuscular volumes [17]. The concordance of these relatively recent estimates points to the need to recognize and address iron deficiency anemia in women of childbearing ages in Ethiopia. While it is possible that some of the approximately 11% of women with anemia that does not appear to be from iron deficiency might have elevated ferritin levels as an acute phase protein or hemoglobinopathy, it is more likely that other micronutrient deficiencies are the problem. Vitamin A is a major public health problem in both preschoolers (prevalence of 1.5 Bitot's spots) and mother (night blindness of 2 - 15%) in Ethiopia. Furthermore, folic acid is another nutrient deficiency observed among women of reproductive age [6, 11, 26, 33].

Although some crops, notably teff, are high in iron [26] and fermented enset may increase non-heme iron absorption [36], a marked observation, in slightly more than half of the subjects with anemia, in the present study is the low intake of meat which is a source of heme iron. Heme iron is not only better absorbed than non-heme obtained from plant source food, whose absorption may range from 1-10%, but also has an enhancing effect on absorption. The finding that about one-third of the women with anemia in this study had vegetables less than once a day suggests low consumption of vitamin C and could be another substantiating factor for the existence of iron deficiency anemia. This dietary pattern would also result in low levels of zinc which was found to be a strong predictor for hemoglobin in pregnant women in Southern Ethiopia [17]. A study with children in Ethiopia [15] which included a thorough assessment of dietary intake showed that dietary iron was adequate but bioavailability was restricted because the type of iron was non-heme and there was inadequate vitamin C, additionally, absorption was further reduced due to the presence of inhibitory factors such as tannins, phenols, and fiber [15]. These findings and ours strongly suggest that iron deficiency anemia in Ethiopia can be explained by dietary factors.

Despite the various types of nutrition interventions that have been implemented in Ethiopia, cultural food taboos and religious fasts persist among different ethnic, religious, age and gender groups. Taboos have limited the development and utilization of certain plant and animal food resources, with detrimental effect particularly on mothers and children. Camel meat and milk are avoided by Christians and many pagan people in the south traditionally avoid chicken and eggs while the Oromo, Afar, Somali, and other pastoralist groups avoid fish. The rejection of fish and most wild animals as food has persisted in most pastoralist groups. Aversion to eating ensete (Ensete ventricosum) and the meat of pigs and goats spread with the southward migrations of the northern Ethiopians. In addition, food avoidance in the form of reluctance to eat vegetables and fruit are widespread in grain growing areas [33]. Increasing animal food consumption through poultry rearing and small ruminants [13] and intensification of backyard gardening to ensure availability and increased consumption of vegetables and fruits is recommendation to partly address the problem.

As expected, due to cumulative obstetric conditions and maternal exhaustions, the prevalence of anemia among the age groups between 31-49 years was higher than the age group 15-20 and 21-30 years in descending orders. Such observations are not uncommon to see in most sub-Saharan and African countries [5, 17]. Women frequently enter pregnancy with insufficient nutrient stores, and thus the increased demand associated with pregnancy and later with lactation is reported to cause anemia [7, 34]. This holds true in most African countries and Ethiopia could not be the exception given the high rates of micro and macronutrient deficiencies resulting from the interaction of deficient dietary intake and the deeply entrenched food habits [13, 33].

Although the presence of parasitic infections, particularly hookworm, is associated with bleeding and higher levels of iron deficiency [2] this was not found in our study which again substantiates our assertion that iron deficiency anemia is mainly caused by dietary factors in Ethiopia. Nonetheless, anemia was significantly higher in women with history of illness and the association was retained even when the variable was adjusted for its confounding effect in the logistic regression models signifying that another cause of anemia to some extent is chronic illnesses as well.

A limitation to this study is lack of more precise estimates of nutrient intake due to the methods of dietary assessment. Further any data based on recall such as the food frequency information is subject to bias as well. Also, it is possible that a bias was introduced due to missing data since not all women selected systematically for the biological collections had complete blood data. Limitations such as these are common challenges when doing field work with large samples.

This study is the first of a large sample of women from nine of the eleven regions in Ethiopia and reveals an overall prevalence of iron deficiency anemia that can be considered a health problem. The dependency on a single staple crop results in shortage of minerals and vitamins which may lead to iron deficiency anemia and therefore should be addressed within the country. Additionally, weekly iron-folic acid supplementation in areas where the prevalence of anemia exceeds 20% to vulnerable groups particularly the pregnant and lactating women together with health education is warranted to achieve several of the United Nation's Millennium Development Goals. Although anemia can be caused by non-nutritional factors [3, 4] in our study there was no association between parasitic infestations and anemia. However, chronic illnesses such as TB and probably HIV were found statistically significant in both bi-variate as well as the logistic regression models [13, 17] suggesting that chronic illness could be the second important causes for anemia in women of childbearing ages in Ethiopia.