Existing reports focus on zinc-associated immunity and infection in malnourished children; however, whether zinc also plays an important role in the immune homeostasis of the non-zinc-deficient population remained unknown. This study aimed to investigate the association between zinc status and toll-like receptor (TLR)-related innate immunity and infectious outcome in well-nourished children. A total of 961 blood samples were collected from 1 through 5 years of age. Serum zinc was analyzed, and mononuclear cells isolated to assess TNF-α, IL-6, and IL-10 production by ELISA after stimulation with TLR ligands. Childhood infections were analyzed as binary outcomes with logistic regression. The prevalence of zinc deficiency was 1.4-9.6% throughout the first 5 years. There was significant association between zinc and TLR-stimulated cytokine responses. Higher serum zinc was associated with decreased risk of ever having pneumonia (aOR: 0.94; 95% CI: 0.90, 0.99) at 3 years, and enterocolitis (aOR: 0.96; 95% CI: 0.93, 0.99) at 5 years. Serum zinc was lower in children who have had pneumonia before 3 years of age (72.6 ± 9 vs. 81.9 ± 13 μg/dL), and enterocolitis before 5 years (89.3 ± 12 vs. 95.5 ± 13 μg/dL). We emphasize the importance of maintaining optimal serum zinc in the young population.
Keywords: childhood infection; cytokines; innate immunity; serum zinc; toll-like receptors; zinc deficiency; zinc-sufficient.