Plant-Based Diet for Hypertension: Should You Change Now for Success?

Hypertension, or high blood pressure, increases the risk of developing cardiovascular diseases like heart attacks and stroke.

Diet is a modifiable factor that can be tailored to lower blood pressure, and therefore, research must be conducted to identify foods that would maximally benefit hypertensive patients.

Large-scale studies such as the EPIC-Oxford trial and the Adventist Health Study-2 (AHS-2) with nearly 10,000 participants reported lower BP readings among plant-based food consumers than meat-eaters. 

Is the data strong enough to support shifting to a diet of whole plant foods to lower your blood pressure? A recent review set out to analyze that. 

Purpose of Review

Accumulating data on the consumption of plant-based diets and their impact on blood pressure indicate a consensus that plant-based diets are linked to reduced blood pressure. The suggested mechanisms of action are manifold, and, in this systematic review, we provide a summary of the most recent findings on plant-based diets and their impact on blood pressure, along with an analysis of the molecules accountable for the observed effects.

Recent Findings

The overwhelming majority of intervention studies demonstrate that plant-based diets result in lower blood pressure readings when compared to diets that are based on animal products. The various mechanisms of action are being clarified.

Results of Review

Overall, 39 studies were analyzed. Plant-origin diets included different diets with a high content of whole grains, vegetables, and fruits, including the vegetarian diet and its modifications (including lacto-ovo-vegetarian and lacto-vegetarian diets); the Mediterranean (Med) diet; the healthy Nordic diet; and the Dietary Approach to Stop Hypertension (DASH) diet [including the Japanese cuisine-based DASH (J-DASH)].

Most RCTs reported that plant-based diets lowered BP values more than animal-based diets. A recent meta-analysis, including 32.0 cross-sectional design studies and >20,000 individuals, showed lower average BP values among individuals consuming vegetarian foods than omnivorous foods.

Likewise, a recently published meta-analysis including 187.0 individuals from five RCTs documented a lowering of systolic BP (SBP) and diastolic BP (DBP) by 5.47 mmHg and 2.3 mmHg, respectively, among individuals consuming lacto-ovo-type vegetarian diets, with high and moderate quality of evidence for the changes in SBP and DBP values, respectively.

Another meta-analysis, including 856 individuals from 15 RCTs, showed a significant reduction in SBP and DBP of 2.7 and 1.7 mmHg, respectively, related to vegetarian diets than plant- and animal-based diets. Vegans demonstrated a greater reduction in SBP  (3.1 mmHg) than lacto-ovo-vegetarians (1.8 mmHg). Similarly, among vegans, DBP values were reduced by 1.9 mmHg.

DASH diets also lowered BP compared to control diets, particularly among hypertensive patients and African American individuals, with reductions in SBP and DBP values of 5.5 and 3.8 mmHg, respectively, and high certainty of evidence.

In a meta-analysis of four prospective, eight cross-sectional studies involving >30,000 individuals and 6,342 patients with metabolic syndrome (MetS), BP showed a significant but inverse relationship with consuming Mediterranean diets (relative risk, 0.9). Similar results were obtained in ≥three meta-analyses with moderate-quality evidence.

Further, a meta-analysis, including 420 participants from three RCTs, showed that Nordic diets lowered SBP and DBP values by 4.5 and 2.3 mmHg, respectively, compared to the comparator diets.

Recent trials such as PREDIMED and PREDIMED-Plus reported that adhering to Mediterranean diets decreased the need to escalate antihypertensive treatment among individuals consuming two antihypertensive drugs and showed cardioprotective effects.

Vitamin C (ascorbic acid) increases the levels of tetrahydrobiopterin, a critical cofactor for endothelial nitric oxide synthase (eNOS) activity to stimulate stimulates endothelium-derived nitric oxide (EDNO) synthesis.

Potassium may exert antihypertensive effects. Polyphenols in foods such as thyme, olive, artichoke, and beetroot increase vasomotion, preserve endothelial function.  Omega-3 fatty acids, particularly docosahexaenoic acid (DHA) and alpha-linolenic acid (ALA), improve vasodilator responses.

Summary

The data in this systematic review support the concept that plant-based diets are associated with lower blood pressure and overall better health outcomes (namely, on the cardiovascular system) when compared to animal-based diets. 

The data indicate that plant-based diets, particularly the Dash and Med diets, favoring vegetable, fruit, and whole grain consumption and limiting sodium, sugar, processed, and red meat intake, can lower blood pressure and have better cardiometabolic outcomes than animal-based diets.