Iron, zinc, Vitamin A and selenium status in a cohort of Indonesian infants after adjusting for inflammation using several different approaches

Abstract

Inflammation confounds the interpretation of several micronutrient biomarkers resulting in estimates that may not reflect the true burden of deficiency. We aimed to assess and compare the micronutrient status of a cohort of Indonesian infants (n 230) at aged 6, 9 and 12 months by ignoring inflammation (unadjusted) and adjusting four micronutrient biomarkers for inflammation with C-reactive protein (CRP) and α-1-glycoprotein (AGP) using the following methods: (1) arithmetic correction factors with the use of a four-stage inflammation model; and (2) regression modelling. Prevalence of infants with any inflammation (CRP>5 mg/l and/or AGP>1 g/l) was about 25% at each age. Compared with unadjusted values, regression adjustment at 6, 9 and 12 months generated the lowest (P<0·001) geometric mean (GM) for serum ferritin (26·5, 14·7, 10·8 μg/l) and the highest GM for serum retinol-binding protein (0·95, 1·00, 1·01 μmol/l) and Zn (11·8, 11·0, 11·5 μmol/l). As a consequence, at 6, 9 and 12 months regression adjustment yielded the highest prevalence of Fe deficiency (20·3, 37·8, 59·5 %) and the lowest prevalence of Vitamin A (26·4,16·6, 17·3 %) and Zn (16·9, 20·6, 11·0 %) deficiency, respectively. For serum Se, irrespective of adjustment, GM were low (regression: 0·73, 0·78, 0·81 μmol/l) with prevalence of deficiency >50 % across all ages. In conclusion, without inflammation adjustment, Fe deficiency was grossly under-estimated and Vitamin A and Zn deficiency over-estimated, highlighting the importance of correcting for the influence of such, before implementing programmes to alleviate micronutrient malnutrition. However, further work is needed to validate the proposed approaches with a particular focus on assessing the influence of varying degrees of inflammation (i.e. recurrent acute infections and low-grade chronic inflammation) on each affected nutrient biomarker.