High blood pressure is a leading risk factor for mortality and a major preventable cause of disability worldwide. Nutritional and lifestyle factors are key determinants of blood pressure across populations, and lifestyle modifications—including weight reduction if overweight or obese, reduced dietary sodium intake, increased dietary potassium intake, moderation of alcohol consumption, adoption of the DASH (dietary approaches to stop hypertension) diet, and regular aerobic exercise—are effective at reducing blood pressure.1

In the linked study (doi: 10.1136/bmj.a258), Tzoulaki and colleagues assess the association between iron and red meat intake and blood pressure using data from the international collaborative study of macro-/micronutrients and blood pressure (INTERMAP), a large cross sectional study of the nutritional determinants of blood pressure across 17 population samples from Japan, China, the United Kingdom, and the United States.2 The authors found significant inverse associations between intake of total iron and non-haem iron and systolic blood pressure. Conversely, intake of red meat was significantly associated with increased systolic blood pressure, but the association …