Background/Aims: Improved flow mediated dilatation (FMD) has been reported in some but not all weight loss studies. Restricting sodium is known to improve FMD. It is unclear whether weight loss combined with reduced sodium will have a greater benefit on FMD. This study aimed to determine the effects of weight loss and reduced sodium intake on FMD.
Methods: Participants were randomly assigned to two groups, in a parallel design. All participants reduced sodium intake by 50mmol for one week. Group1 (weight loss) then used low sodium meal replacements for weight loss, and Group2 (control, no weight loss) continued their usual diet for 8 weeks. Adherence was assessed using 24hr urinary sodium excretion. FMD, blood pressure (BP), and 24hr urinalysis were measured at baseline and at completion of each intervention phase.
Results: 25 participants (14 women; BMI:34.7±5.9kg/m2; age: 42±16y) were enrolled and 23 participants completed the protocol. FMD (2.3±1.1%, p=0.04, n=25) and DBP (-2.7±10mmHg, p=0.01, n=25) improved after the sodium reduction. During the weight loss phase, mean weight change was -3.0±3.3kg Group1 (n=13) and +1.1±1.2kg Group2 (n=10) (p=0.02). There were no between group differences in FMD during the weight loss phase. Urinary sodium decreased in Group1 (-87±18mmol/d, p<0.01) and Group2 (-95±25mmol/d, p<0.01) during sodium restriction, and remained lower (Group1: -67±20mmol/d, p=0.01; Group 2: -69±24mmol/d, p=0.02) during the weight loss phase.
Conclusion: These results suggest reducing sodium intake improves FMD but the combination of modest weight loss does not provide additional benefit.
Funding source: Heart Foundation and Government of South Australia