Metabolic syndrome and salt sensitivity of blood pressure in non-diabetic people in China: a dietary intervention study

Abstract

Summary Background We aimed to examine the association between the metabolic syndrome and salt-sensitivity of blood pressure (BP). Methods 1,906 Chinese aged ≥16 years without diabetes were fed a low-sodium diet (51.3 mmol/day) for 7 days followed by a high-sodium diet (307.8 mmol/day) for an additional 7 days. BP were measured at baseline and at the end of each intervention period using a random-zero sphygmomanometer. Metabolic syndrome was defined as the presence of ≥3 risk factors: abdominal obesity, high triglyceride, low high-density-lipoprotein-cholesterol, elevated BP, and elevated glucose. Findings Multivariable-adjusted mean changes (95% confidence intervals) in BP (mmHg) were significantly greater (all p<0.0001) among participants with compared to those without the metabolic syndrome: −7.34 (−8.21, −6.46) versus −5.17 (−5.51, −4.83) for systolic BP and −4.56 (−5.28, −3.85) versus −2.47 (−2.74, −2.19) for diastolic BP during the low-sodium intervention; and 6.51 (5.76, 7.26) versus 4.55 (4.26, 4.84) for systolic BP and 3.25 (2.56, 3.94) versus 1.69 (1.42, 1.96) for diastolic BP during the high-sodium intervention. In addition, compared to those with zero, participants with 4 or 5 risk factors for the metabolic syndrome had a 3.54-fold increased odds (2.05, 6.11) of high salt-sensitivity during the low-sodium intervention and a 3.13-fold increased odds (1.80, 5.43) of high salt-sensitivity during the high-sodium intervention. Interpretation These results suggest that the metabolic syndrome significantly enhances BP response to sodium intake. Reduction in sodium intake may be an especially important component in reducing BP among patients with multiple risk factors for the metabolic syndrome.