HTN: Dietary Magnesium 2008
Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.
If magnesium is proposed as a therapy to reduce blood pressure, advise that the effect of magnesium as a single nutrient on blood pressure in healthy or hypertensive adults is unknown. The effect of dietary patterns with magnesium intake above the DRI on blood pressure in healthy or hypertensive adults is minimal. However, some dietary patterns that contain magnesium lower than recommended levels (DRI) may be associated with elevated blood pressure.
Risks/Harms of Implementing This Recommendation
Conditions of Application
This recommendation applies to individuals asking about magnesium as a therapy to reduce blood pressure.
Potential Costs Associated with Application
- Three cross-sectional studies of dietary patterns with magnesium intakes below recommended levels report an association with increased blood pressure, however, it is unclear if this association is confounded by other dietary factors (Liu et al, 2001; Hajjar and Kotchen, 2003; Zhao et al, 2004)
- One randomized controlled trial of 35 patients with essential hypertension receiving combination therapy (potassium and magnesium supplementation 217.2 mg K and 70.8 mg Mg per day) for four weeks showed a significant reduction in blood pressure from baseline, but overall dietary intake of magnesium was not assessed (Wu et al, 2006).
- One cohort study did not report significant differences between hypertensive and normotensive subjects, although both groups reported low magnesium intakes (Lancaster et al, 2004).
- One cross-sectional study with magnesium intakes near recommended levels reported no statistically significant differences in blood pressure between hypertensive patients and controls (Silaste et al, 2000).
- One meta-analysis of 253 studies of dietary patterns with magnesium intakes above recommended levels showed a minimal decrease in blood pressure (Geleijnse et al, 2004).
Recommendation Strength Rationale
- Conclusion Statement is a Grade II
- Risks/Harms of Implementing This Recommendation
The recommendations were created from the evidence analysis on the following questions. To see detail of the evidence analysis, click the blue hyperlinks below (recommendations rated consensus will not have supporting evidence linked).
What is the relationship between magnesium intake and blood pressure in healthy and hypertensive adults?
Geleijnse JM, Kok FJ, Grobbee DE. Impact of dietary and lifestyle factors on the prevalence of hypertension in Western populations. Eur J Public Health. 2004; 14 (3): 235-239.
Hajjar I, Kotchen T. Regional variations of blood pressure in the United States are associated with regional variations in dietary intakes: The NHANES III Data. J Nutr. 2003; 133: 211-214.
Lancaster KJ, Smiciklas-Wright H, Weltzel LB, Mitchell DC, Friedman JM, Jensen GL. Hypertension-related dietary patterns of rural older adults. Preventive Medicine, 2004; 38: 812-818.
Liu L, Liu L, Ding Y, Huang Z, He B, Sun S, Zhao G, Zhang H, Miki T, Mizushima S, Ikeda K, Nara Y, Yamori Y. Ethnic and environmental differences in various markers of dietary intake and blood pressure among Chinese Han and three other minority peoples of China: results from the WHO Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. Hypertens Res. 2001; 24 (3): 315-322.
Silaste M-L, Junes R, Rantala AO, Kauma H, Lilja M, Savolainen MJ, Reunanen A, Kesaniemi YA. Dietary and other non-pharmacological treatments in patients with drug-treated hypertension and control subjects. Journal of Internal Medicine. 2000; 247: 318-324.
Wu G, Tian H, Han K, Xi Y, Yao Y, Ma A. Potassium magnesium supplementation for four weeks improves small distal artery compliance and reduces blood pressure in patients with essential hypertension. Clin Exp Hypertens. 2006; 28 (5): 489-497.
Zhao L, Stamler J, Yan LL, Zhou B, Wu Y, Liu K, Daviglus ML, Dennis BH, Elliott P, Ueshima H, Yang J, Zhu L, Guo D, for the INTERMAP Research Group. Blood pressure differences between northern and southern Chinese: role of dietary factors. The international study on macronutrients and blood pressure. Hypertension, 2004; 43 (6): 1,332-1,337.
References not graded in Academy of Nutrition and Dietetics Evidence Analysis Process
The Dietary Reference Intakes (DRI) and Recommended Dietary Allowances (RDA) are issued by the Food and Nutrition Board of the Institute of Medicine, National Academy of Sciences.