Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This systematic review and meta-analysis evaluated the association between whole grain and refined grain consumption and the risk of developing hypertension, focusing on prospective cohort studies. Given the growing public health burden of hypertension globally, understanding dietary factors such as whole grain intake is essential for both individual and regulatory decision-making. The review included studies identified through comprehensive searches in PubMed and Embase up to July 2024, adhering to PRISMA guidelines. Both high versus low consumption and dose-response relationships were analyzed using random effects models, with additional analyses for nonlinearity and subgroup effects. The strength of evidence was graded using established criteria, and extensive sensitivity and subgroup analyses were performed to assess robustness and sources of heterogeneity.
Who was reviewed?
The meta-analysis synthesized data from nine prospective cohort studies on whole grains (182,617 participants, 33,582 hypertension cases) and five studies on refined grains (58,590 participants, 16,074 cases), spanning the US, Europe, and Asia. Seven studies included both sexes, two focused on men, and one on women, with participants aged 18 to 85.9 years. The studies varied in whole grain and refined grain definitions, intake measurement methods, and degree of adjustment for confounders such as BMI, physical activity, and education. The quality of included studies ranged from medium to high, as assessed by a modified Newcastle Ottawa Scale.
Most important findings
| Critical Point | Details |
|---|---|
| Whole grain intake and hypertension | High whole grain consumption was linked to a 26% lower risk of hypertension (RR 0.74, 95% CI 0.59–0.93). |
| Dose-response for whole grains | Each additional 90 g/day of whole grain intake (about 3 slices of bread) reduced hypertension risk by 14%. |
| Linear relationship for whole grains | The association was linear; a 22% reduction in hypertension risk was seen at 200 g/day versus none. |
| Heterogeneity | High in high vs. low analysis (I²=97%), but lower in dose-response; differences were mainly in magnitude. |
| Confounding & robustness | Association persisted after adjusting for BMI, alcohol, physical activity, and dietary factors. |
| Subgroup consistency | No significant heterogeneity by sex, geography, study quality, or confounder adjustment. |
| Refined grain intake and hypertension | No significant association observed (RR 0.94, 95% CI 0.88–1.01 per high vs. low intake). |
| Publication bias | No evidence of publication bias detected with Egger’s or Begg’s tests. |
| Biological plausibility | Whole grains’ fiber content may reduce obesity and improve endothelial function and blood pressure. |
| Evidence grading | Evidence for whole grains: probable causal relationship; refined grains: limited, inconclusive. |
Key implications
The findings strongly support increasing whole grain intake as part of public health recommendations to reduce hypertension risk. For heavy metal certification programs, promoting whole grain consumption aligns with cardiovascular risk reduction, but attention to potential heavy metal content in whole grains remains important for regulatory oversight and industry compliance.
Citation
Aune D, Metoudi M, Sadler I, Kassam S. Whole grain and refined grain consumption and the risk of hypertension: a systematic review and meta-analysis of prospective studies. Sci Rep. 2025;15:21447. doi:10.1038/s41598-025-05197-5
