Cadmium affects blood pressure and negatively interacts with obesity: Findings from NHANES 1999-2014

Inconsistencies are noted regarding the association between cadmium exposure and blood pressure/hypertension and the interaction between cadmium and body mass index (BMI). This study aims to clarify these inconsistencies in a large sample (n = 32,791) of adults age ≥20 years from eight cycles of the US National Health Examination and Nutrition Survey (NHANES, 1999-2014). The cadmium levels in blood (BCd) and urine (UCd) were used as exposure biomarker. Multiple-linear/logistic regression models were built and stratified by sex, ethnicity and BMI category. The interaction between BCd and BMI was assessed on additive and multiplicative scales. A twofold increase in BCd was associated with 0.54 mm Hg (95% CI: 0.49, 0.58) and 0.05 mm Hg (95% CI: 0.04, 0.06) increases in the systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively, in black women. The SBP and DBP increased by 0.92 mm Hg (95% CI: 0.73, 1.11) and 0.85 mm Hg (95% CI: 0.65, 1.05), respectively, in Mexican-Am women. Significant associations were found between BCd and hypertension in them (systolic risk per twofold BCd, OR = 1.31; 95% CI: 1.07, 1.61; and diastolic risk per twofold BCd, OR = 1.55; 95% CI: 1.17, 2.05). UCd was significantly associated with hypertension in all individuals (OR = 1.14 per twofold; 95% CI: 1.07, 1.21). The associations between cadmium exposure and blood pressure/hypertension showed some discrepancies across BMI categories. A negative interaction was observed between BCd and obesity with regard to their effects on systolic hypertension (RERI = -0.30; 95% CI: -0.56, -0.03; ratio of ORs = 0.55; 95% CI: 0.35, 0.89). Our findings provided evidence for the effect of cadmium on blood pressure and the prevalence of hypertension in American adults. The associations showed discrepancies by sex and ethnicity. The negative interaction between cadmium exposure and obesity influenced systolic hypertension risk.