PURE-Sodium: Benefits of Sodium Restriction Dependent on Sodium Consumption, BP and Age

"An important part of this study also was the ability to convert a single urine sample of sodium into an estimated daily intake, which is a very convenient tool for a large population study," said Alfred Bove, MD, MACC.
The benefits of dietary sodium restrictions are more strongly associated with initial blood pressure levels in older individuals who are hypertensive and consume high levels of sodium than in younger people who are not hypertensive and consume less sodium, according to results from the PURE-Sodium Study released on Sept. 3 at the ESC Congress 2013 in Amsterdam.

The study, based on 99,114 men and women ages 35 to 70 years from 628 rural and urban communities in 17 countries, estimated participants' 24-hour urinary sodium and potassium excretion from a single morning fasting specimen using the Kawasaki formula, measured participants' blood pressure levels and assessed the association between urinary sodium levels and blood pressure levels.

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Mean sodium excretion levels ranged from 3.8 g per day in Malaysia to 5.5 g per day in China. Each 1 gm (43.5 mmol) increase in sodium excretion was associated with a 2.56 mmHg increase in systolic blood pressure and a 1.05 mmHg increase in diastolic blood pressure (p < 0.001). The investigators found no association between sodium excretion levels less than 3 g per day and blood pressure levels; a weak to modest association between sodium excretion levels of 3 to 5 g per day and blood pressure levels; and a strong association between sodium excretion levels greater than 5 g per day and blood pressure levels.

They also found a stronger association between high sodium excretion levels and blood pressure levels in participants with hypertension than in those without hypertension (p < 0.001) and in people age 55 years or older than in younger individuals (p < 0.001).

"Sodium excretion is more strongly related to blood pressure in those with high sodium excretion levels, high blood pressure and older individuals," said the study's presenter, Andrew Mente, PhD, assistant professor of clinical epidemiology and biostatistics at McMaster University and the Population Health Research Institute in Hamilton, Canada.

"The benefits of sodium reduction will depend on the level of sodium consumption and the individual's initial blood pressure and age. Dietary sodium is more strongly related to blood pressure in those with high sodium consumption and high blood pressure, with little association in those with sodium consumption below 3 grams per day," he said. "Our findings have implications for international guidelines and public health strategies."

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