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Cardiovascular Disease  |  Type 2 Diabetes  |  HIV+  |  Weight Loss and Maintenance

Mutivitamins and Hypertension

Introduction

The most convincing evidence supporting the use of multivitamins in reducing elevated blood pressure comes from a single large intervention study conducted in a micronutrient deficient population.

Intervention studies

In the Linxian Intervention Trial, a six year randomized, placebo controlled trial conducted in a rural population of Chinese adults with a micronutrient-poor diet, Mark et al. [1] found that taking two 100% DV multivitamin/mineral supplements per day reduced the prevalence of elevated blood pressure (both systolic and diastolic).  The effects of this supplement regimen were more pronounced in men. 

Observational studies

In a more recent study of women enrolled in the Nurses’ Health Study I (1990-1998) and Study II (1991-1999) by Forman et al. [2], the use of folate-containing supplements, including multivitamins, was associated with a decreased risk of incident hypertension, particularly among the younger cohort (Study II).  The association between supplemental folic acid and the risk of incident hypertension was examined by restricting the populations to those who consumed < 200 μg/d of folate from diet alone.  In this subgroup, the women in the highest total folate category (≥ 800 μg/d), i.e., those who derived most of their folate from supplements, were compared to those in the lowest category of intake (< 200 μg/d).  No independent association between multivitamin use and risk of hypertension was found in either cohort when compared to the women who did not take multivitamins.

Multivitamin supplements formulated to support normal blood pressure

The Dietary Approaches to Stop Hypertension (DASH) diet has a demonstrated effect on significantly reducing elevated blood pressure levels in adults [3,4].  The hypotensive effects of this diet are attributable in some degree to the presence (or absence) of specific nutrients.  The low fat dairy foods and the increased number of fruit and vegetable servings recommended in the DASH diet provide plenty of calcium, magnesium, vitamin C and potassium (and very little sodium).  Multivitamin preparations formulated to support blood pressure often include the beneficial micronutrients provided by the DASH diet.  Interestingly, the micronutrient dosages provided by these multivitamin preparations often do not reach the same levels provided by the DASH diet. 

Critical Thinking Questions:

• Would the multivitamin dosage provided in the Linxian Trial be appropriate for most Americans?

• How is blood pressure evaluated in these studies, and are these methods reliable?

• Can a single multivitamin pill be formulated to contain all of the same micronutrients at the same levels as the DASH diet?

• Why are potassium and calcium present at < RDA levels in most standard multivitamins?

• Could the micronutrient requirements for hypertensive patients be higher than RDA levels?

• Could a standard multivitamin supplement interfere with any of the drugs commonly prescribed for high blood pressure?

Professional Societies, Agencies, and Government Organizations:

• National Heart, Lung, and Blood Institute

• DASH Eating Plan - http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/

• Primary Prevention of Hypertension - http://www.nhlbi.nih.gov/health/prof/heart/hbp/pphbp.pdf