Reference Number: 687
Year: 2025
Link: Link to original paper
Health: Blood pressure
Nutrition: Whole grain
Summary
Abstract
A high intake of whole grains has been associated with a reduced risk of hypertension, however, studies have not been entirely consistent. Findings regarding refined grains and hypertension have also been inconsistent. We conducted a systematic review and meta-analysis of prospective cohort studies on whole grain and refined grain consumption and hypertension risk. PubMed and Embase databases were searched up to 25th of July 2024. Random effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs) for the association between whole grain and refined grain intake and hypertension. Restricted cubic splines were used to investigate potential nonlinear associations. Nine cohort studies were included in the meta-analysis. The summary RR (95% CI) for high vs. low whole grain intake was 0.74 (0.59–0.93, I2 = 97%, pheterogeneity<0.001, n=9) and per 90 g/d was 0.86 (0.82–0.90, I2=63%, pheterogeneity=0.008, n=8). The summary RR (95% CI) for high vs. low refined grain intake was 0.94 (0.88–1.01, I2=7.9%, pheterogeneity=0.36, n=5) and per 90 g/d was 0.97 (0.93–1.02, I2=0%, pheterogeneity=0.42, n=4). There was no indication of publication bias in either analysis, although the number of studies was low for refined grains. There was no evidence of nonlinearity for whole grains (pnonlinearity=0.31) or refined grains (pnonlinearity=0.21), and for whole grains there was a 22% reduction in risk at 200 vs. 0 g/d. These findings provide further support for a beneficial role of whole grain consumption in relation to hypertension risk and support recommendations to increase whole grain intake in the general population. No clear association was observed between refined grains and risk of hypertension.
Summary of Findings
This study examined whether eating more wholegrain foods is linked to a lower risk of developing hypertension (high blood pressure), and whether eating refined grains has the opposite effect. Instead of running a new experiment, the researchers combined and analysed results from many long term population studies. This type of research is called a systematic review and meta?analysis, and it provides a clearer picture than any single study alone.
The team searched the scientific literature for prospective cohort studies, studies that follow people over time, record what they eat, and track who develops hypertension later. They included nine studies, covering more than 182,000 adults from different countries. These studies typically followed participants for several years.
They then used statistical methods to combine the results and examine dose–response relationships—that is, whether eating more whole grains leads to progressively lower risk.
Key findings
The results were consistent and showed a clear pattern:
1. Higher whole?grain intake was linked to a significantly lower risk of developing hypertension.
- People who ate the most whole grains had a 26% lower risk of hypertension compared with those who ate the least.
- There was a dose?response effect: Every additional 90 grams per day of whole grains (roughly 3 servings) was associated with a 14% reduction in hypertension risk.
This means that even moderate increases in wholegrain intake could meaningfully reduce long?term blood pressure risk.
2. Refined grains did not show a protective effect.
- Across the included studies, refined?grain consumption was not associated with lower hypertension risk.
- In some analyses, higher refined?grain intake even showed a trend toward higher risk, although results were not consistent enough to be conclusive.
The authors discuss several possible mechanisms of why whole grains may help:
- Whole grains contain more fibre, which may improve blood vessel function and reduce inflammation.
- They have a lower glycaemic impact than refined grains, helping stabilise blood sugar and insulin.
- Whole grains provide magnesium, potassium, antioxidants, and phytochemicals, all of which support healthy blood pressure regulation.
Significance for the baker
The study provides strong, up?to?date evidence that eating more whole grains can help prevent hypertension, while refined grains offer no such benefit. The findings support the BALM protocol that encourages replacing refined grains with whole grain alternatives as part of a long term strategy for cardiovascular health.
