Exploring the interplay between blood pressure, blood pressure variability, dietary minerals, and vascular health

Abstract

Background: Hypertension (HT) is the leading cause of cardiovascular diseases (CVD) and premature mortality worldwide, with its prevalence rising while awareness remains consistently low. Dietary factors such as sodium and potassium intake play a crucial role in blood pressure (BP) regulation and thus are strongly linked to the development of HT. Beyond conventional BP measurements, BP variability (BPV) is also an emerging risk factor for CVD which is also affected by dietary intake. Indeed, BPV has been shown to be associated with target organ damage and the occurrence of subclinical atherosclerosis as detected by increased carotid intima-media thickness (CIMT). Nevertheless, the detail relationships between dietary nutrients, BP, BPV, and vascular health in healthy populations remain unclear. Objectives: This study examines relationships between BP, BPV, CIMT, dietary sodium, potassium, sodium-to-potassium ratio (Na/K), and urinary sodium excretion (a biomarker of sodium intake) in middle-aged Chinese adults without symptomatic CVD. Subclinical carotid atherosclerosis is defined as CIMT above the study population’s 75th percentile. Methods: From July 2018 to January 2022, 268 Chinese adults aged 40–65 years, without HT, hyperlipidaemia, diabetes, or known CVD, were recruited. Participants underwent office BP measurements, 24-hour ambulatory BP monitoring (ABPM) to assess BP and short-term BPV (standard deviation [SD]; coefficient of variation [CV]), CIMT evaluation via carotid Doppler ultrasonography, 3-day food diary analysis for dietary sodium and potassium using FoodWorks software, and spot urine collection for urinary sodium excretion. Results: Participants had a mean age was 53.8±6.7 years and 43% of them were men. Among them, 67 had increased CIMT (>75th percentile of the study population). Participants with increased CIMT exhibited higher office systolic BP [SBP] (118.8±10.9 vs. 115.6 11.2 mmHg, P<0.05), day-time SBP (126.6±11.8 vs. 121.8±12 mmHg, P<0.01), and night-time SBP (115.9±12.1 vs. 111.0±11.6 mmHg, P<0.01) than those with normal CIMT. Nevertheless, after adjusting of confounding variables, logistic regression only revealed significant negative association between CIMT with day-time SBP SD (Odd Ratio [OR]=0.93, 95% confidential interval [CI] 0.86-0.99, P<0.05) and CV (OR=0.88, 95%CI 0.79-0.97, P<0.05). Further analysis of the relationships between the dietary intake of sodium and potassium, and spot urine sodium secretion demonstrated that only urine sodium excretion has significant negative correlation with CIMT (OR=0.93, 95% CI 0.87-0.99, P<0.05), but no dietary intake of sodium, potassium, and sodium/potassium (Na/K) ratio (All P>0.05). Subsequent analysis of the effects of spot urine sodium excretion on different BP parameters showed that urine sodium only inversely correlated with day-time SBP (β=-0.35, P<0.05) and day-time BPV (SBP SD: β=-0.21, P<0.01; diastolic BP [DBP] SD: β=-0.18, P<0.05; SBP CV: β=-0.14, P<0.05; DBP CV: β=-0.16, P<0.05). Conclusions: In this study, both increased day-time SBP BPV and increased urine sodium excretion are associated with protective effects against atherosclerosis in healthy Chinese adults. Moreover, the results also revealed that decreased urine sodium excretion was linked with increased both SBP and DBP BPV. These results provide important novel insights on the independent mechanisms by increasing sodium intake or increasing day-time SBP BPV to prevent the development of subclinical atherosclerosis.