Available data indicate that
dietary sodium (as
salt) relates directly to blood pressure (BP). Most of these findings are from studies lacking dietary data; hence, it is unclear whether this
sodium-BP relationship is modulated by other dietary factors. With control for multiple nondietary factors, but not body mass index, there were direct relations to BP of 24-hour urinary
sodium excretion and the urinary
sodium/
potassium ratio among 4680 men and women 40 to 59 years of age (17 population samples in China, Japan, United Kingdom, and United States) in the INTERMAP (International Study on Macro/
Micronutrients and Blood Pressure), and among its 2195 American participants, for example, 2 SD higher 24-hour urinary
sodium excretion (118.7 mmol) associated with systolic BP 3.7 mm Hg higher. These
sodium-BP relations persisted with control for 13 macronutrients, 12
vitamins, 7 minerals, and 18
amino acids, for both sex, older and younger, blacks, Hispanics, whites, and socioeconomic strata. With control for body mass index,
sodium-BP-but not
sodium/
potassium-BP-relations were attenuated. Normal weight and obese participants manifested significant positive relations to BP of urinary
sodium; relations were weaker for
overweight people. At lower but not higher levels of 24-hour
sodium excretion,
potassium intake blunted the
sodium-BP relation. The adverse association of
dietary sodium with BP is minimally attenuated by other dietary constituents; these findings underscore the importance of reducing
salt intake for the prevention and control of
prehypertension and
hypertension.
CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00005271.