Magnesium supplements were found to help lower blood pressure in 11 trials compared with placebo.

Daniel T Dibaba, Pengcheng Xun, Yiqing Song, Andrea Rosanoff, Michael Shechter, Ka He The effect of magnesium supplementation on blood pressure in individuals with insulin resistance, prediabetes, or noncommunicable chronic diseases: a meta-analysis of randomized controlled trials. First published July 19, 2017, doi: 10.3945/​ajcn.117.155291 Am J Clin Nutr

ajcn155291 http://ajcn.nutrition.org/content/early/2017/07/19/ajcn.117.155291.abstract?papetoc