In a recent study published in Current hypertension reports Journal, researchers conducted a systematic review to evaluate the effect of eating plant foods on an individual’s blood pressure (BP).
High blood pressure, or high blood pressure, increases the risk of cardiovascular diseases such as heart attack and stroke.
Diet is a modifiable factor that can be adapted to lower blood pressure, and therefore, research needs to be done to determine which foods would benefit hypertensive patients the most.
Large-scale studies such as the EPIC-Oxford Trial and Adventist Health Study-2 (AHS-2) with nearly 10,000 participants have reported lower BP readings among vegetarian food eaters than meat eaters.
Similar observations were reported in Phase I and II of the Nurses’ Health Study (NHS-I and II), the Health Professionals Follow-up Study (HPFS), and the Coronary Artery Risk Development Among Young People (CARDIA) study.
Assessing the effect of diet on blood pressure can aid in decision-making and improve standard of care for individuals with hypertension.
In the current systematic review, researchers evaluated the effect of plant foods on BP.
Databases such as PubMed, Scopus, and the Web of Science were searched for randomized controlled trials (RCTs) on the effects of plant-based diets on blood pressure. Only studies published in English from 2020 onwards were included in the analysis.
Search terms such as “vegetarian diet,” “hypertension,” “Mediterranean diet,” and “blood pressure” were used with Boolean operators such as “OR” and “AND” among the search terms.
Data search was based on the guidelines for systematic reviews and meta-analyses (PRISMA). Data on essential blood pressure-lowering components of plant-based diets were also analyzed.
The team excluded articles related to the design, rationale, and essential variables of an ongoing or future study, reviews, book chapters, conference papers, and clinical practice data.
In addition, basic cross-sectional studies; Studies in which diet was not the only study exposure; animal studies; Non-randomized controlled studies Studies of diets that were not specifically from plant sources; Studies in which diets from plant sources were not the primary exposure studied; Studies in which results were not distinguished between groups; Studies for which diet was not the main exposure were excluded from the analysis.
Initially, 8422 records were identified, of which only 39 eligible studies were considered for the final analysis.
Plant-based diets included various diets high in whole grains, vegetables, and fruits, including the vegetarian diet and its modifications (including vegan, lacto-, and vegan diets); Mediterranean diet (Med); The Scandinavian Healthy Diet. and the Dietary Approaches to Stop Hypertension (DASH) Diet [including the Japanese cuisine-based DASH (J-DASH)].
Most randomized controlled trials reported that plant-based diets lower blood pressure values more than animal-based diets. A recent meta-analysis, including 32.0 cross-sectional design studies and >20,000 individuals, showed lower mean BP values among individuals consuming plant foods compared to omnivores.
Similarly, a recently published meta-analysis including 187.0 individuals from five randomized controlled trials documented reductions in systolic blood pressure (SBP) and diastolic BP (DBP) of 5.47 mmHg and 2.3 mmHg, respectively, among individuals consuming a vegetarian diet. lacto- and ovo-type, with high and medium quality of evidence for changes in SBP and DBP values, respectively.
Another meta-analysis including 856 individuals from 15 randomized controlled trials showed significant reductions in SBP and DBP of 2.7 and 1.7 mm Hg, respectively, for vegetarian diets compared to plant and animal-based diets. Vegetarians showed a greater decrease in SBP (3.1 mmHg) than lacto-ovo vegetarians (1.8 mmHg). Similarly, among vegetarians, DBP values were reduced by 1.9 mmHg.
DASH diets also lowered blood pressure compared to control diets, particularly among hypertensive patients and African American individuals, with lower SBP and DBP values of 5.5 and 3.8 mmHg, respectively, and significant certainty of evidence.
In a meta-analysis of four prospective, eight cross-sectional studies including more than 30 000 individuals and 6342 patients with the metabolic syndrome (MetS), BP showed a significant but inverse relationship with Mediterranean diets consumed (relative risk, 0.9). Similar results were obtained in three meta-analyses with moderate quality evidence.
Moreover, a meta-analysis, which included 420 participants from three randomized controlled trials, showed that the Scandinavian diets lowered SBP and DBP values by 4.5 and 2.3 mmHg, respectively, compared to the comparison diets.
Recent trials such as PREDIMED and PREDIMED-Plus reported that adherence to Mediterranean diets reduced the need for escalation of antihypertensive treatment among individuals consuming two antihypertensive drugs and showed cardioprotective effects.
Vitamin C (ascorbic acid) increases levels of tetrahydrobiopterin, a critical cofactor for endothelial nitric oxide synthase (eNOS) activity to stimulate endothelial-derived nitric oxide (EDNO) synthesis.
Potassium may exert antihypertensive effects by altering sodium and potassium adenine triphosphate (ATPase) activity, stimulating cellular hyperpolarization, decreasing calcium ion concentration, promoting vasoconstriction, and inhibiting sodium reabsorption.
Polyphenols found in foods such as thyme, olives, artichokes, and beets increase vasoconstriction, maintain endothelial redox status, and promote eNOS hydroxylation.
Omega-3 fatty acids, particularly docosahexaenoic acid (DHA) and alpha-linolenic acid (ALA), inhibit cyclooxygenase and nicotinamide adenine dinucleotide oxidase 4 (Nox 4) activity, reduce superoxide production, and improve vasodilator responses.
Based on the study findings, plant-based diets, particularly the DASH and Med diets, which favor the intake of vegetables, fruits, and whole grains and limit intake of sodium, sugar, processed meat, and red meat, can lower blood pressure and produce better cardio-metabolic outcomes than established diets. on animals.