LAUSR

Objectives Determine if children (6 to 23 mo) who received daily preventive zinc (PZ; 7 mg/d), daily high-zinc, low-iron micronutrient powder (MNP; 10 mg/d zinc, 6 mg/d iron) or therapeutic zinc during episodes of diarrhea (TZ; 20 mg/d for 10 d per episode) have improved markers of innate and adaptive immune function, compared to placebo (PL). Methods Rural Laotian children were recruited into a double-blind, randomized, controlled intervention trial for 9 mo. Venous blood was collected at baseline (BL) and endline (EL) for analysis. Primary outcomes included T-cell subsets (naïve and memory CD4, CD8, Tregs) measured by flow cytometry and production of T-cell cytokines (IL-2, IL-10, IL-13, IL-17A, INF-γ) and LPS-induced cytokines (IL-1β, IL-6, IL-10, TNF-α by whole blood cultures. Blood leukocytes (including lymphocytes, neutrophils, monocytes and eosinophils) were measured as secondary outcome variables. Group means at EL were compared by analysis of covariance (controlling for BL values of the outcome, sex, child age, district, month of enrollment and plasma zinc concentration). If an interaction with BL plasma zinc (above/below median) was observed, group means were compared separately in children above and below the median. Results Mean BL plasma zinc in all children (N = 574) was 0.55 ± 0.12 mg/L. No significant group differences were seen at EL in the primary outcomes. For secondary outcomes, the counts (^103/μL) of lymphocytes from the PZ group (5.02 ± 0.16) were significantly lower than the PL group (5.64 ± 0.16; P = 0.032). The EL counts (^103/μL) of from the PZ group (0.144 ± 0.026) were significantly lower than in the PL (0.279 ± 0.048; P = 0.036) and TZ (0.285 ± 0.047; P = 0.025) groups among children with baseline zinc below the median. Conclusions Primary outcomes (T-cell subsets, and cytokine production) were not affected by the zinc intervention. Lymphocyte and eosinophil concentrations may be affected by zinc treatment but this result requires confirmation. Funding Sources ARS Project 2032-53000-001-00-D, Mathile Institute for the Advancement of Human Nutrition.