Assessment of gene–nutrient interactions on inflammatory status of the elderly with the use of a zinc diet score — ZINCAGE study

Although zinc plays an important role in health status of the elderly, their dietary habits in relation to zinc intake are not well documented. The main objective of the current study was the assessment of dietary zinc intake in European old populations and the investigation of its impact on plasma zinc and inflammatory cytokines concentrations, in relation to genetic markers. Within the ZINCAGE study, 819 healthy old Europeans (≥60 years old) were recruited. Plasma zinc, interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured. Genotype data were obtained for the −174G/C polymorphism in the IL-6 gene. Dietary data were collected with a food frequency questionnaire and were used to calculate a zinc diet score. Zinc score was validated using additional dietary data (24-h recalls), in a subsample of 105 subjects. Zinc score was different among most of the European centres (P<.001), while an age-dependent decline was documented (P=4.4×10−12). Plasma zinc concentrations were significantly correlated with the zinc score (standardized β=0.144, P=8.8×10−5). The minor allele frequency for the −174G/C polymorphism was f(C) 0.31. There was a significant interaction of zinc diet score and GG (−174G/C) genotype on higher plasma IL-6 levels (β±S.E.=0.014±0.0, P=.008). The main finding of our study was the detection of gene–nutrient and biochemical–nutrient interactions in a multiethnic cohort based on a common dietary assessment tool.