Dietary Magnesium, C-Reactive Protein and Interleukin-6: The Strong Heart Family Study

Abstract

Background: Recent studies suggest that dietary factors, particularly magnesium (Mg) intake, influence systemic inflammation. Whether these associations are modified by genes associated with Mg metabolism and transport is unknown. Objective: To examine the associations of reported Mg intake, and the interaction of reported Mg intake with single nucleotide polymorphisms (SNPs) related to Mg metabolism and transport, on markers of inflammation (i.e., C-reactive protein (CRP) and interleukin 6 (IL-6)) among American Indians (AIs). Methods: This cross-sectional study included AI participants (n=1,924) from the Strong Heart Family Study. Intake of Mg from foods and dietary supplements was ascertained using a 119-item Block food frequency questionnaire. CRP and IL-6 were measured from blood collected after a 12-hour fast, and candidate SNP (rs3740393) was genotyped using MetaboChip. Generalized estimating equations were used to examine associations of Mg intake, and the interaction of rs3740393 x dietary Mg, on CRP and IL-6. Results: Reported Mg intake was not associated with CRP or IL-6. We observed no interaction of reported Mg intake with rs3740393 on CRP. However, we observed a significant interaction (p-interaction=0.018) of reported Mg intake with rs3740393 on IL-6. Among participants with the G/G genotype, for every 1 SD higher in log-Mg, log-CRP was 0.04 (95% CI: -0.10 to 0.17) mg/l higher. Among participants with the C/G genotype, for every 1 SD higher in log-Mg, log-CRP was 0.08 (95% CI: -0.21 to 0.05) mg/l lower, and among participants with the C/C genotype, for every 1 SD higher in log-Mg, log-CRP was 0.19 (95% CI: -0.38 to -0.01) mg/l lower. Conclusion: Among SHFS participants, dietary intake of Mg is not associated with CRP (irrespective of genotype). However, Mg intake is associated with lower IL-6 among carriers of the C allele at rs3740393. Future research is necessary to replicate this finding, and to examine other Mg-related genes that may influence associations of Mg intake with inflammation.