Association between blood pressure and dietary factors in the Dietary and Nutritional Survey of British Adults

Objectives: To measure the associations among blood pressure, hypertension, and recorded dietary factors. Methods: Data were analyzed from the computer file of the Dietary and Nutritional Survey of British Adults, in which persons of both sexes aged 16 to 64 years living in private households (excluding pregnant women) had been randomly selected from the United Kingdom Electoral Register. Main outcome measures were systolic blood pressure, diastolic blood pressure, and hypertension (defined as systolic blood pressure of greater than or equal to 140 mm Hg, diastolic blood pressure of greater than or equal to 90 mm Hg, or both, or receiving antihypertensive medication). Results: After controlling for 24-hour urinary potassium excretion, age, obesity, alcohol intake, and season of interview, a single measure of 24-hour urinary sodium excretion was significantly associated with systolic blood pressure (P less than or equal to.001), diastolic blood pressure (P<.05), and hypertension (P=.009). These associations persisted after controlling for many variables of blood chemistry and dietary intake. Conclusions: Sodium is positively associated with blood pressure over a range of sodium excretion rates from 70 to 400 mmol/d. This finding supports the international consensus that the risk of hypertension is lower when salt intake is lower and suggests that a proportion of the British population has a sodium excretion rate that is habitually low enough to have some preventive effect.