Looking for a natural way to lower blood pressure? Whole grains might be the answer

By Hugo Francisco de SouzaReviewed by Susha Cheriyedath, M.Sc.Jul 2 2025

Replacing refined grains with whole grains could be a simple yet powerful step to reduce your risk of hypertension, according to the largest analysis of its kind to date.

Study: Whole grain and refined grain consumption and the risk of hypertension: a systematic review and meta-analysis of prospective studies. Image Credit: marilyn barbone / Shutterstock

In a recent systematic review and meta-analysis published in the journal Scientific Reports, researchers investigated the associations between the dose-dependent consumption of grain subtypes (whole grain versus refined grain) and the subsequent risk of hypertension.

Their study leveraged data from nine cohort studies, which were compiled across two online scientific repositories (PubMed and Embase), comprising data from over 182,000 individuals. Review findings revealed several beneficial associations between whole-grain consumption and hypertension risk.

Notably, individuals in the highest strata of whole-grain intake were 26% less likely to develop hypertension than their counterparts in the lowest strata. This association was found to be linear and dose-dependent. Every additional 90 g of whole grains consumed daily (equivalent to three slices of whole-grain bread or one bowl of whole-grain cereal) reduced the risk of hypertension by a further 14%. In contrast, no clear association was demonstrated between refined grain intake and hypertension.

These findings support dietary guidelines that advocate for whole-grain substitutions in the prevention of hypertension.

Background

Colloquially termed ‘high blood pressure’, hypertension is a non-communicable cardiovascular condition characterised by the higher-than-normal force of blood pushing against a patient’s artery walls. While independently medically alarming, untreated or poorly treated hypertension can quickly exacerbate into heart disease, stroke, kidney failure, and other potentially lethal comorbidities.

Unfortunately, hypertension is a silent pandemic estimated to impact more than 1.28 billion adults globally, almost half of whom remain unaware of their condition. The disease is assumed to claim more than 10 million lives annually, with predictions painting an even grimmer future picture.

Evidence suggests that modifiable health behaviors (diet, physical activity, sleep quality, etc.) are strongly associated with hypertension outcomes. While weight, salt intake, and physical activity are well-known risk modifiers, the role of specific food choices remains under scrutiny.

Epidemiologists have long suspected that whole grains (cereals containing all three kernel parts), rich sources of fiber, vitamins, minerals, and phytochemicals, may help regulate blood pressure. However, individual cohort studies have produced mixed results, and a comprehensive assessment of the effects of refined versus whole grain on hypertension was needed.

About the study

The present systematic review addresses this knowledge gap by conducting a timely meta-analysis of prospective studies examining grain intake and the incidence of hypertension. Its methodology and outcome reporting adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Publications with the potential for review and meta-analysis inclusion were obtained from the PubMed and Embase repositories from the database's initiation until July 2024. All case-cohort, within-cohort, nested case-cohort, and prospective cohort studies reporting relative risk estimates (aRRs) for associations between grain consumption (whole-grain and/or refined) and hypertension outcomes were included in the downstream review and analyses.

Statistical analyses included relative risks (RRs), sample demographic and medical data, and publication details meta-data extraction, comparing highest-versus-lowest intakes of grains subtypes, and conducted dose-response analyses (Greenland and Longnecker’s protocol) per 90 g/day increments.

The Newcastle-Ottawa Scale and the World Cancer Research Fund grading criteria were used to assess publication quality and the strength of evidence, respectively. Using the latter, the authors graded the evidence for whole grains as supportive of a 'probably causal' relationship, while the evidence for refined grains was deemed 'limited-no conclusion.'

Random-effects models (DerSimonian and Laird) were used to account for between-study variability. Heterogeneity and publication bias were assessed via I2 and funnel plots. The authors noted that, although there was no indication of publication bias, the analysis for whole grains revealed very high heterogeneity, suggesting significant variability in the results of the included studies.

Furthermore, they acknowledged that a high intake of whole grains may be associated with a generally healthy lifestyle, which could potentially confound the results. However, significant risk factors were adjusted for in the analysis. Refined grains included white bread, white rice, and pastries, while whole grains were defined as foods containing all grain parts--bran, germ, and endosperm.

Sensitivity analyses excluded single studies to test robustness. Authors also explored whether overall dietary quality, adjustment for various confounders, or differences in demographic factors affected the associations. All models were adjusted for potential statistical confounds.

Study findings

Of the 6,360 publications identified during the keyword search, sequential screening of the publication titles, abstracts, and full texts identified nine publications for meta-analysis. Analyses have unequivocally demonstrated that whole-grain intake reduces the risk of hypertension. Participants in the highest whole-grain consumption group had a 26% lower risk of hypertension (RR = 0.74, p < 0.001, n = 9) compared to their counterparts in the lowest consumption group.

This relationship followed a linear, dose-dependent pattern: consuming 90g of whole grains daily reduced the risk of hypertension by 14% (RR = 0.86, p = 0.008, n = 8). The paper discusses several plausible biological mechanisms for this effect, including the high dietary fiber content in whole grains, which improves insulin sensitivity and endothelial function, as well as the potential benefits of antioxidants and their impact on the gut microbiome.

In contrast, refined grain showed no statistically meaningful association with hypertension.

Conclusions

This meta-analysis supports dietary guidelines urging the replacement of refined grains with healthier whole-grain alternatives. It demonstrates how even modest increases can reduce the risk of hypertension by approximately 14% or more. With hypertension claiming more than 10 million lives each year, population-level grain shifts may offer meaningful public health benefits.

Clinicians and policymakers should promote the consumption of high-quality whole grains for comprehensive cardiovascular health. Future research is warranted to confirm these findings through additional studies, particularly with sex-stratified analyses and data from regions outside North America.