Zinc status of riverside populations of the rivers Solimoes and Negro in the state of Amazonas, Brazil

Abstract

Zinc nutrition has been shown to be critically limiting among urban populations of the central Amazon valley, but no information on the zinc status of rural populations has been published. Nutrition surveys were carried out on the river Solimoes and the river Negro in years 1976/7. Hair samples collected at that time were analysed for their zinc content, by Atomic Absorption Spectrophotometry. The mean hair zinc value of children aged under seven years from the river Negro (140 µg/g) was about one third lower than hair values from the river Solimoes (204 µg/g) with high statistical significance (p< 0.001). Hair zinc levels were influenced by a variety of non-dietary conditions in these riverine children populations, including anthropometric classifications and gastrointestinal parasites, and these are discussed. The significantly lower hair zinc levels in children on the river Negro than in children on the river Solimoes may be part of the reason why young child stunting rates are higher on the river Negro. The importance of zinc status for reproduction is also discussed, especially the evidence for relationships to still teratogenesis and still births, the latter being six times more common among mothers on the river Negro than among those on the Solimoes at that time. Although no indicators of maternal zinc status were measured, the findings of zinc deficiency in their young children support the hypothesis that these mothers were also suffering from zinc deficiency. It also suggests poor zinc status may be associated with the lower population densities found along the banks of the river Negro as compared to that of the river Solimoes. The situation seems unlikely to have improved in the forty years since these observations were made and may even be getting worse. Interventions are suggested that would allow this type of situation to be remedied.