Eleven RCTs were included (485 patients).
Studies were conducted in Australia, USA, UK and Germany. The authors considered the mean BP changes in normotensive and hypertensive subject to be comparable and hence the studies suitable for combining in a meta-analysis. 92.8% of subject completed the trials. Sample sizes ranged from 7 to 111. The average trial quality score was 73 (range 58 to 86).
A chronic high NaCl diet significantly increased the mean SBP and DBP by 5.58 (95% CI: 4.31, 6.85) and 3.5 mmHg (95% CI: 2.62, 4.38) respectively.
There was a significant association between the level of NaCl intake and SBP (P = 0.05, r squared = 0. 37) but not DBP (P =0.76, r squared = 0.01).
A chronic high NaCl diet increased the mean SBP and DBP more for trials with only patients >= 60 years compared to trials with a mean age close to 60 years:
>= 60 years (5 RCTs): Trials with mean age close to 60 years (4 RCTs): A chronic high NaCl diet significantly increased the mean SBP and DBP by 3.27 (95% CI: 1.23, 5.31) and 2.69 mmHg (95% CI: 1.44, 3.94) respectively.