Relatively little information is available on the nutritional situation of indigenous children in Latin American countries. A recent compilation by the Pan American Health Organization of findings regarding the nutritional situation of indigenous children, based on the reference curves proposed by the World Health Organization , identified levels of undernutrition varying from 35 to 60% among Quechua and Aymara children in Bolivia and Peru, about 55% in indigenous children in Ecuador, and approximately 75% in indigenous children in Guatemala . Thus, in many Latin American countries, rates of undernutrition among indigenous children tend to be much higher than those of non-indigenous children.
During the last two decades in Brazil there have been marked public policy improvements for indigenous peoples with implications for public health. For example, beginning in the 1990’s, the decennial national census included “indigenous” to the list of possible responses for the question on race or skin color . During the same period, a distinct healthcare subsystem was implemented for indigenous peoples . These policies aimed at improving the availability of health information, which demonstrated empirically that large inequalities exist between indigenous peoples and other segments of Brazilian society, particularly in relation to morbidity and mortality, which are part of a pernicious cycle marked by persistent poverty, exclusion, and disease.
Prior to the National Survey, the great majority of available information on the nutritional status of indigenous children in Brazil came from case studies carried out over the past two decades in specific communities and local populations, most located in Amazonia [14, 22, 23, 47–50]. These case studies found levels of stunting well above those reported for non-indigenous children (see Leite et al.  for a review).
The results of the National Survey also reveal a very unfavorable nutritional scenario for indigenous children in the country. As compared to non-indigenous Brazilian children nationally, the present rate of stunting in indigenous children in Brazil (25.7%) is substantially higher than the current rate but comparatively close to that reported four decades ago [13, 52]. The results of national household surveys since the 1970s show stunting (following the WHO growth curves ) in non-indigenous children < 5 years of age decreased sharply from 37.1% in 1974/1975 to 7.1% in 2006 .
Considered by major geopolitical region, the rates of stunting in indigenous children in Brazil ranged from two to five times higher than those observed for non-indigenous children. As reported by the Brazilian Ministry of Health , the rates of stunting among non-indigenous children in this age group were 5.5% in the Central-West, 5.6% in the Southeast, 5.8% in the Northeast, 8.5% in the South, and 14.7% in the North, the latter region presenting the highest index of poverty and the worse indicators of general health in the country.
A combination of factors is likely to be acting to increase the prevalence of undernutrition among indigenous children in Brazil. Stunting and underweight are closely related to chronic exposure to unfavorable socioeconomic and environmental conditions, poor energy and nutrient intake, and recurrent infectious and parasitic disease [53, 54]. Previous studies have explained unfavorable rates of undernutrition among indigenous peoples in Brazil in terms of the impacts of increased participation in the market economy, reduced access to natural resources and land, sedentarization, and increased environmental contamination due to poor sanitary conditions, among other factors [14, 20, 55–58]. Consistent with these interpretations, in the multivariate analysis, we observed that such social determinants as household environmental characteristics, hospitalization, and socioeconomic condition were associated with higher prevalence of stunting and underweight.
Alternative explanations for the elevated prevalence rates of low height-for-age observed among indigenous children may be found in the human biology literature. For example, some lines of investigation draw on genetic-evolutionary hypotheses that populations in tropical forested environments tend to present smaller adult body size as an adaptive response to alleged environmental pressures (e.g., food restriction and high temperatures and humidity) [59, 60]. According to such perspectives, the standard growth reference curves used in our analyses would not be applicable to some ethnic populations (such as indigenous peoples in the Amazon region of Brazil) due to a distinct genetic growth potential. However, in the field of public health nutrition, the relative weight of genetics is considered to be greater on final height achieved at the end of the growth period than on growth rates during infancy. Until at least the seventh year of life, human growth potential is essentially uniform worldwide, independent of region or ethnic group. During this phase of life, environmental factors (e.g., living conditions, sanitation, socioeconomic and education levels, diet, food security, coinfection, and access to health services) are considered to play a more dominant role in determining the distinct growth achievements observed among children in different populations [61–66]. It is now widely accepted that undernutrition is a multifaceted condition that cannot be fully understood on the basis of its immediate biological determinants – socioeconomic and ethnic disparities are at the root of the problem, particularly in countries that show sharp inequalities with regards to income, education, and access to health care [2, 67–71].
Our data show an increase in the prevalence of stunting in the first 3 years of life. Indeed, among children less than 6 months of age the prevalence was 9.2%, whereas for those aged 24–35 months the prevalence was 32.7%. A small decrease in the prevalence of stunting was observed among children older than 36 months. These data suggests that there is no cohort effect in the studied population. Such increments in the prevalence of stunting reported in case studies of South American indigenous peoples were found to be strongly related to poor environmental conditions and weaning practices [14–17].
We observed substantially higher prevalence rates of stunting and underweight in the North region of the country as compared with all other regions. After controlling for maternal age, maternal schooling, the household goods index, presence of trash collection service in the village, maternal anemia, and birth weight, the prevalence ratio of stunting among children living in the North decreased from 1.83 to 1.58 (CI 95%: 1.07-2.34), whereas for underweight the prevalence ratio decreased from 2.87 to 1.91 (CI 95%: 1.04-3.51). These results demonstrate the close relationship between the higher rates of undernutrition observed in the North region and socioeconomic conditions, which have undergone major changes for indigenous populations in recent decades due to the rapid pace of economic development and environmental transformation in the region.
As we reported previously , the findings of the National Survey highlight major gaps in the availability of public services to indigenous villages in Brazil, such as education, basic sanitation, safe drinking water, and solid waste management. These are conditions that favor the occurrence of high levels of undernutrition in children, as was observed in the present study. With regard to the management of human waste, the most typical infrastructure observed was that of a simple pit latrine, with sewage rarely being collected or receiving any kind of treatment. Even in more developed regions of the country, such as the South/Southeast, nearly 40% of households in the sample reported defecating in the open. Only 5.9% of the households reported possessing any kind of sewage system. The management of household waste was also found to be precarious, with trash most commonly being discarded, burned, or buried in the peridomicile or elsewhere in the village.
Unfortunately, considering these inadequate sanitary conditions, it is unsurprising that children also present elevated levels of morbidity due to infectious and parasitic diseases. As previously reported, the National Survey found the proportion of reported hospitalizations of children during the prior 12 months to be elevated, with 19.3% of children being hospitalized during this period . Diarrhea and respiratory infection were frequent causes of hospitalization. With respect to referred morbidity during the prior week, about one in four children (23.6%) presented diarrhea. Additionally, 51.2% of indigenous children nationally were found to be anemic. The health scenario outlined here for indigenous children facilitates the interaction between undernutrition and infection, widely described and characterized in the literature as cyclical and mutually reinforcing, not only because undernutrition contributes to increasing the severity and duration of infection, but also because recurrent infections tend to worsen the nutritional status of children [72–75].
Among infants younger than six months, those who were breastfed were less likely to be underweight or stunted, but the confidence intervals included the unity. Because breastfeeding was almost universal among infants younger than 6 months, with only 5.2% of infants in this age group not being breastfed at the time of the interview, the precision of the estimate on the effect of breastfeeding in this age group was low. On the other hand, breastfeeding did not protect children older than 12 months against stunting or underweight. Among older children, the benefits of breastfeeding may be overwhelmed by weaning foods with lower energy and nutrient content or contamination with microorganisms in situations of poverty or inadequate sanitation .
The results presented here regarding the nutritional status of indigenous children from the First National Survey of Indigenous People’s Health and Nutrition in Brazil reveal striking health inequities involving a diverse set of socioeconomic and environmental factors. High prevalence rates of undernutrition were shown to be associated with socioeconomic variables including income, household goods, schooling, and access to sanitation services. They were also shown to be associated with breastfeeding, which is a highly cultural dimension of child dietary practices among many indigenous societies. Whereas the National Survey was the first study to address child nutrition among the indigenous peoples in Brazil on a national scale, providing important baseline data for future comparison, these findings further suggest the relevance of social, economic, and environmental factors at different scales (local, regional, and national) for the nutritional status of indigenous peoples.
Although the Brazilian Unified Health System (Sistema Único de Saúde – SUS) prioritizes the promotion of social and economic equity as part of public health research and promotion formulations, the findings reported here indicate that the full potential benefits of this policy orientation are not yet observable in the health and nutrition profile of the indigenous child population at a national scale. The worrying nutritional health profile of indigenous children in Brazil underscores the need for greater attention to this population segment by the Brazilian government.
Food and nutrition policies and interventions designed for indigenous peoples in Brazil must be tailored for consonance with the cultural lifestyles and food perceptions of target communities, going beyond the generalized distribution of energy-rich food items, typical of both governmental and non-governmental food relief initiatives. Measures aimed at improving childhood nutrition may potentially have immediate results, particularly with regards to stimulating child weight gain and improving child survival. Any intervention aimed at indigenous peoples in Brazil, however, must take into consideration this country’s enormous sociocultural diversity, with as many as 300 indigenous ethnic groups and over 200 indigenous languages living in diverse environmental settings. With so many distinctive societies within the Brazilian borders, it is all the more important to implement public health policies and measures aimed at reducing child undernutrition that incorporate sociocultural, economic, environmental, and biomedical dimensions of the problem (see Caldas and Santos  for a recent review of the development of nutrition policies aimed at indigenous peoples in Brazil).
Public policies must also address the need for more research on factors that remain understudied in indigenous populations despite being considered important underlying determinants of child nutritional status in accordance with the United Nations Children’s Fund’s framework for the causes of undernutrition [78, 79]. For instance, research into cultural factors influencing childcare practices, including breastfeeding, weaning, and pregnancy, has the potential to help disentangle many of the complexities subsumed by standardly used variables that do not have uniform meaning in cross-cultural contexts, such as income, wealth, and maternal education.