Primary prevention of CVD: modification of diet in people with hypertension

Overview

General background | Focus of the review | Comments on evidence | Search and appraisal summary | Substantive changes at this update | Abstract | Cite as

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General background

Hypertension (persistent diastolic blood pressure of 90 mmHg or greater or systolic blood pressure 140 mmHg or greater) affects 20% to 35% of the world's adult population and increases the risk of cardiovascular disease, end-stage renal disease, and mortality. Dietary modification is important to consider because it has the potential to reduce blood pressure independently from antihypertensive drugs. In patients treated with drugs, successful dietary modification can lead to dose or medication reductions. In addition, dietary modification may have benefits over and above blood pressure reduction, such as improvements in health-related quality of life.[1]

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Focus of the review

Dietary modification is an important potential treatment for hypertension. Dietary modifications that are effective and safe can improve blood pressure control and reduce the need for antihypertensive drugs. If dietary modifications are made as a component of an overall commitment to a healthier lifestyle, improvements beyond blood pressure reduction could potentially be realised. There are many diets that have been considered for people with hypertension, including low fat and low carbohydrate diets, weight-reducing, and vegetarian diets, but we have focused on the following selected dietary modifications for this update: low-salt (including the DASH diet); Mediterranean-style diets; and supplementary calcium, magnesium, or potassium.

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Comments on evidence

RCTs and systematic reviews of RCTs were evaluated in this overview for establishing efficacy of selected dietary interventions. Hard clinical endpoints were preferred. However, there were, overall, few studies examining the effect of dietary modification on cardiovascular disease endpoints and mortality. Thus, the majority of evidence presented here relates to changes in blood pressure, though this is an established surrogate for cardiovascular disease and cardiovascular deaths.

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Search and appraisal summary

The update literature search for this overview was carried out from the date of the last search, December 2007, to October 2013. A back search from 1966 was performed for the new options added to the scope at this update. For more information on the electronic databases searched and criteria applied during assessment of studies for potential relevance to the overview, please see the Methods section. Searching of electronic databases retrieved 669 studies. After deduplication and removal of conference abstracts, 464 records were screened for inclusion. Appraisal of titles and abstracts led to the exclusion of 376 studies and the further review of 88 full publications. Of the 88 full articles evaluated, three systematic reviews and three RCTs were added at this update.

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Substantive changes at this update

Mediterranean-style diet New option. One systematic review added.[25] Categorised as 'likely to be beneficial'.

Low-salt diet (including the DASH diet) One systematic review updated.[29] Two RCTs added.[30][31] Categorisation unchanged as 'likely to be beneficial'.

Magnesium supplementation One systematic review updated.[42] Categorisation unchanged (unknown effectiveness).

Potassium supplementation One RCT added.[46] Categorisation changed from 'unknown effectiveness' to 'likely to be beneficial'.

Abstract

INTRODUCTION: Hypertension (persistent diastolic blood pressure of 90 mmHg or greater or systolic blood pressure 140 mmHg or greater) affects 20% to 35% of the world's adult population and increases the risk of cardiovascular disease, end-stage renal disease, and mortality. METHODS AND OUTCOMES: We conducted a systematic overview, aiming to answer the following clinical question: What are the effects of selected dietary modification for people with hypertension? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2013 (BMJ Clinical Evidence overviews are updated periodically; please check our website for the most up-to-date version of this overview). RESULTS: At this update, searching of electronic databases retrieved 669 studies. After deduplication and removal of conference abstracts, 464 records were screened for inclusion in this overview. Appraisal of titles and abstracts led to the exclusion of 376 studies and the further review of 88 full publications. Of the 88 full articles evaluated, three systematic reviews and three RCTs were added. We performed a GRADE evaluation for eight PICO combinations. CONCLUSIONS: In this systematic overview, we categorised the efficacy for five interventions based on information about the effectiveness and safety of calcium supplements, a low-salt diet (including the DASH diet), magnesium supplements, a Mediterranean diet, and potassium supplements.

Cite as

Padwal R, Hackam D, Khan N, Tobe S. Primary prevention of CVD: modification of diet in people with hypertension. Systematic review 214. BMJ Clinical Evidence. . 2016 January. Accessed [date].

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