Conflicting Associations among Bioelectrical Impedance and Cardiometabolic Health Parameters in Young White and Black Adults

Abstract

Purpose The purpose of this cross-sectional evaluation was to determine the associations between raw bioelectrical impedance and cardiometabolic health parameters in a sample of young non-Hispanic White and African-American adults. Methods A total of 96 (F: 52, M: 44) non-Hispanic White (n = 45) and African-American adults (n = 51) between the ages of 19 and 37 (22.7 ± 3.83 y) completed several fasted assessments including resting systolic blood pressure (rSBP), blood glucose (FBG), blood lipids, and bioelectrical impedance spectroscopy (BIS). BIS derived measurements included phase angle (PhA), bioimpedance index (BI), impedance ratio (IR), reactance index (XCi), fat-free mass (FFM), FFM index (FFMi), and absolute (a) and relative (%) total body water (TBW) and extra- (ECF) and intracellular fluid (ICF). All bioelectric variables were collected at 50 kHz other than IR (250 kHz/5 kHz). Multiple regressions were conducted and adjusted for sex, age, and BMI. Results rSBP was positively, and HDL was inversely, associated with all bioelectrical impedance and absolute hydration variables (all p ≤ 0.050) other than XCi for rSBP and XCi and FFMi for HDL. rSBP (p < 0.001) was inversely, and HDL (p = 0.034) was positively, associated with IR. FBG was positively associated with BI, XCi, FFM, TBWa, and ECFa (all p < 0.050). Metabolic syndrome severity was positively associated with BI, FFM, TBWa, and ECFa for females (all p ≤ 0.050) and with ICFa for African-American females (p = 0.016). Conclusions Given the rapid increase in the prevalence of cardiometabolic health risks among young adults and the broad use of bioelectrical impedance in practice, the conflicting associations we observed in this age group suggest that bioelectrical impedance parameters should be used with caution in the context of cardiometabolic health risks and age.