Iron and infection: An investigation of the optimal iron hypothesis in Lima, Peru.

OBJECTIVES: This article explores the optimal iron hypothesis through secondary data analysis of the association between hemoglobin levels and morbidity among children living in Canto Grande, a peri-urban community located on the outskirts of Lima, Peru.

METHODS: Risk ratios were used to test whether lower iron status, assessed using the HemoCue B-Hemoglobin System, was associated with an increased relative risk of morbidity symptoms compared to iron replete status, controlling for infant age, sex, weight for height z-score, maternal education, and repeated measures in 515 infants aged 6-12 months.

RESULTS: Infants with fewer current respiratory and diarrheal morbidity symptoms had a lower risk of low iron deficiency compared to participants who were iron replete (P < .10). Infants with fewer current respiratory infection symptoms had a statistically significant (P < .05) reduction in risk of moderate iron deficiency compared to infants who were iron replete.

CONCLUSION: In this study, morbidity status was not predictive of iron deficient status over a six-month interval period, but nonreplete iron status was shown to be associated with current morbidity symptoms. These results support investigating iron status as an allostatic system that responds to infection adaptively, rather than expecting an optimal preinfection value.