Patients with elevated blood pressure should follow a weight-reducing diet, take regular exercise, and restrict alcohol and salt intake. Available evidence does not support relaxation therapies, calcium, magnesium or potassium supplements to reduce blood pressure.

This systematic review found no statistically significant effect of potassium supplementation on blood pressure. Because of the small number of participants in the two high quality trials, the short duration of follow-up, and the unexplained heterogeneity between trials, the evidence about the effect of potassium supplementation on blood pressure is not conclusive. Further high quality RCTs of longer duration are required to clarify whether potassium supplementation can reduce blood pressure and improve health outcomes.

In view of the poor quality of included trials and the heterogeneity between trials, the evidence in favour of a causal association between magnesium supplementation and blood pressure reduction is weak and is probably due to bias. This is because poor quality studies generally tend to over-estimate the effects of treatment. Larger, longer duration and better quality double-blind placebo controlled trials are needed to assess the effect of magnesium supplementation on blood pressure and cardiovascular outcomes.

In view of the poor quality of included trials and the heterogeneity between trials, the evidence in favour of causal association between calcium supplementation and blood pressure reduction is weak and is probably due to bias. This is because poor quality studies generally tend to over-estimate the effects of treatment. Larger, longer duration and better quality double-blind placebo controlled trials are needed to assess the effect of calcium supplementation on blood pressure and cardiovascular outcomes.

The results suggest that the routine combined use of a thiazide with a beta-blocker should be questioned in the early management of hypertension, particularly in patients who are at increased risk of developing new-onset diabetes. In such patients, the increased risk of developing diabetes may exceed the benefit of blood pressure lowering.

The objective of this review was to evaluate the effectiveness of relaxation to lower high blood pressure. We searched electronic bibliographic databases and grey literature to identify randomized controlled trials comparing relaxation therapies with no active treatment or sham therapy, enrolling adult participants with raised systolic blood pressure (SBP) X140 mm Hg or diastolic blood pressure (DBP) X85 mm Hg and follow-up X8 weeks. Twenty-five trials with up to 5 years follow-up, assessing 1198 participants, met our inclusion criteria and were metaanalysed. Overall, relaxation resulted in small, statistically significant reductions in SBP (mean difference: À5.5 mm Hg, 95% CI: À8.2 to À2.8) and DBP (mean difference: À3.5 mm Hg, 95% CI: À5.3 to À1.6) compared to the control. Substantial heterogeneity between trials (I 2 470%) was not explained by duration of follow-up, type of control, type of relaxation therapy or baseline blood pressure. The 9 trials that reported blinding of outcome assessors found a nonsignificant net reduction in blood pressure (SBP mean difference: À3.2 mm Hg, 95% CI: À7.7 to 1.4) associated with relaxation, as did the 15 trials comparing relaxation with sham therapy (SBP mean difference: À3.5 mm Hg, 95% CI: À7.1 to 0.2). Adequate randomization was confirmed in only seven trials and concealment of allocation in only one. In view of the poor quality of the included trials and unexplained variation between trials, the evidence in favour of a causal association between relaxation and blood pressure reduction is weak. Some of the apparent benefit of relaxation was probably due to aspects of treatment unrelated to relaxation.

We found no robust evidence that supplements of any combination of potassium, magnesium or calcium reduce mortality, morbidity or BP in adults. More trials are needed to investigate whether the combination of potassium & magnesium is effective.

No abstract