SummaryPrevious studies conducted to investigate the relationship between sodium intake and blood pressure in our African population have yielded contradictory results. With the high prevalence of obesity in this population, it is possible that these contradictory findings are due to the masking effects of obesity on this relationship. We measured 24–hour ambulatory blood pressure and 24–hour urine excretion on 547 South Africans of African ancestry. A multivariate regression analysis revealed no independent relationship between 24–hour sodium excretion and blood pressure in the total population sample, but when participants were stratified according to body mass index (BMI) status, there was a significant association between 24–hour sodium excretion and blood pressure in the normal–BMI participants but not in the overweight/obese participants. We concluded that dietary salt intake, indexed by 24–hour urinary sodium excretion, was associated with increased ambulatory blood pressure but this relationship was masked because of a high proportion of overweight/obese individuals in this population.

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Background. A non-dipping blood pressure profile (NDP) is associated with increased arterial stiffness and other cardiovascular target organ damage. Serum lipid profiles have been shown to be important determinants of arterial stiffness. Objective. The aim of the research was to assess serum lipid profiles and arterial stiffness in non-dippers. Methods. This cross-sectional study was conducted involving 796 (288 males and 508 females) participants of black African origin. A twenty-four-hour ambulatory BP monitoring was done using a Spacelabs 90207 (Spacelabs Inc., Redmond, Washington, USA) monitor. Carotid-Femoral pulse wave velocity measurements were performed using a high fidelity SPC-301 micromanometer (Millar instruments Inc., Houston, TX). Results. Of the 288 males, 140 were classified as non-dippers. Of the 508 females, 273 were classified as non-dippers. In the general population, males had higher triglycerides when compared with females 1.46±0.96 vs 1.13±1.02, p<0.0001. Additionally, dipper males had higher serum TRGL when compared with dipper females 1.32±0.98 vs 1.06±0.58, p = 0.0012. Non-dipper males also had higher serum TRGL when compared with non-dipper females 1.61±2.05 vs 1.19±1.14, p=0.0078. Serum HDLc was lower in the non-dipper male group when compared to the non-dipper female group (p=0.008). In both male and female groups, non-dippers had higher CFPWV when compared with dippers; 7.53±3.60 vs 5.74±2.47, p<0.0001 and 6.64±2.52 vs 5.98±2.23, p=0.0021 respectively. However, non-dipper males had significantly higher CFPWV when compared with non-dipper females (7.53±3.60 vs 6.64±2.52, p=0.0031). Conclusions. Therapies targeting a reduction of serum triglycerides levels might be beneficial in improving arterial compliance with or without the presence of non-dipping.

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