People who ate the most nuts had a 16% lower relative risk of developing high blood pressure than those who ate the least, according to a review published in the British Journal of Nutrition. It combined eight studies involving 143,380 people and 20,665 cases of high blood pressure, also called hypertension. British Journal of Nutrition (source, opens in new tab)British Journal of NutritionNut consumption and the risk of hypertension: a systematic review and dose–response meta-analysis of prospective studiesOpen source (opens in new tab) Imperial College London (source, opens in new tab)
Imperial College LondonNut consumption and the risk of hypertension: a systematic review and dose–response meta-analysis of prospective studiesOpen source (opens in new tab)
The studies followed people’s usual diets over time, comparing their reported nut consumption with later diagnoses. This observational approach leaves room for other explanations: people who ate more nuts may also have differed in diet, lifestyle or socioeconomic circumstances that affected their risk.
The researchers also examined how risk varied with the amount eaten. Their model suggested that the association was strongest at around 25–30 g a day, with little further difference above that amount. That amount describes where the observed association levelled off, rather than a proven preventive portion.
The 16% figure compares the risk of a later hypertension diagnosis in the highest and lowest intake groups, rather than changes in blood-pressure readings. It measures a proportional difference between those groups; the corresponding difference in cases per 100 people depends on how common hypertension was in the comparison group.
To examine daily amounts more closely, the researchers combined the intake data in statistical models. One analysis estimated a 20% lower relative risk for each additional 28 g of nuts a day. Another allowed the relationship to curve rather than assuming that risk kept falling at the same rate. It estimated a 26% lower risk at 30 g a day compared with eating no nuts, with the curve flattening around 25–30 g.
The estimates answer different questions: how the highest and lowest intake groups compared, and how risk varied with daily amounts. Results varied substantially between studies in the analysis of daily amounts, adding uncertainty to the size of the estimated association.
The review assessed overall nut consumption. Its findings apply to nuts considered together: the included studies provided no separate results for individual types, such as walnuts and almonds, or for salted and unsalted nuts.
- British Journal of Nutrition · Peer-reviewed studyNut consumption and the risk of hypertension: a systematic review and dose–response meta-analysis of prospective studiescambridge.org · opens in new tab
- Imperial College London · InstitutionNut consumption and the risk of hypertension: a systematic review and dose–response meta-analysis of prospective studiesspiral.imperial.ac.uk · opens in new tab
