Effects of a Mediterranean diet on blood pressure: a systematic review and meta-analysis of randomized controlled trials and observational studies

Abstract

Objective: To conduct a systematic review and meta-analysis investigating effects of MedDiet on blood pressure in randomised controlled trials (RCTs) and associations of MedDiet with risk of hypertension in observational studies.Methods: PubMed, The Cochrane Library and EBSCOhost were searched from inception until January 2020 for studies that met the following criteria: 1) participants aged ≥18 years, 2) RCTs investigating effects of a MedDiet versus control on BP, 3) Observational studies exploring associations between MedDiet adherence and risk of hypertension. Random-effects metaanalyses were conducted. Meta-regression and subgroup analyses were performed for RCTs to identify potential effect moderators.Results: Nineteen RCTs reporting data on 4137 participants and 16 observational studies reporting data on 59,001 participants were included in the meta-analysis. MedDiet interventions reduced systolic and diastolic BP by a mean -1.4 mmHg (95% CI: -2.40 to -0.39 mmHg, p=0.007, I 2 =53.5%, Q=44.7, τ 2 =1.65, df=19) and -1.5 mmHg (95% CI: -2.74 to -0.32 mmHg, p=0.013, I 2 =71.5%, Q=51.6, τ 2 =4.72, df=19) versus control, respectively. Metaregression revealed that longer study duration and higher baseline systolic BP was associated with a greater decrease in BP, in response to a MedDiet (p<0.05). In observational studies, odds of developing hypertension were 13% lower with higher versus lower MedDiet adherence (95% CI: 0.78 to 0.98, p=0.017, I 2 =69.6%, Q=41.1, τ 2 =0.03, df=17).Conclusions: Data suggest that MedDiet is an effective dietary strategy to aid BP control, which may contribute towards the lower risk of CVD reported with this dietary pattern. This study was registered with PROSPERO: CRD42019125073.

Impact of the Level of Adherence to Mediterranean Diet on the Parameters of Metabolic Syndrome: A Systematic Review and Meta-Analysis of Observational Studies

“…This conclusion is in accordance with existing data from previously published studies that have reported a significant inverse correlation between adherence of MD and BP [ 131 , 132 ]. Moreover, two recent meta-analyses showed that MD could significantly reduce BP when compared to control diets [ 133 , 134 ]. In addition, a greater decrease in BP was recorded for subjects presented with higher BP at baseline and in studies with a longer duration of the intervention [ 133 ].…”

“…Moreover, two recent meta-analyses showed that MD could significantly reduce BP when compared to control diets [ 133 , 134 ]. In addition, a greater decrease in BP was recorded for subjects presented with higher BP at baseline and in studies with a longer duration of the intervention [ 133 ]. Various nutrients included in MD exerted beneficial effects through improved vasodilation and endothelial function such as nitric oxides, flavonoids and minerals [ 135 ].…”

Dietary nitrate and population health: a narrative review of the translational potential of existing laboratory studies

“…After the study by Larsen et al [10] in 2006, which first demonstrated a BP lowering effect of sodium NO 3 − , there was a rapid surge in research testing the effects of dietary NO 3 − on health outcomes [89]. However, the research strategy in the last decade has almost taken an inverse approach to that typically adopted in nutritional science as the conduction of clinical trials have surpassed epidemiological investigations, which are generally considered as a first step to validate research hypotheses [90][91][92]. One of the primary reasons for the inverse trend is the lack of reliable and representative food databases of NO 3 − content to support an accurate dietary assessment [93].…”

Feasibility and acceptability of a multi-domain intervention to increase Mediterranean diet adherence and physical activity in older UK adults at risk of dementia: protocol for the MedEx-UK randomised controlled trial

“…However, in a recent analysis of over 8000 participants from the EPIC-Norfolk cohort (UK), we demonstrated that a 3 point increase in MedDiet score on a 14-point or 15-point scale was equivalent to between 1.5 and 5 fewer years of ageing on global cognition, with effects particularly evident in individuals at higher cardiovascular disease (CVD) risk. 16 Potential mechanisms of action for the MedDiet include improved cardiovascular health [17][18][19] and modulation of the gut microbiota 20 along with direct effects on brain glucose utilisation and β-amyloid load. 21 22 Increased PA has also been shown to reduce age-related cognitive decline and dementia risk.…”