Population-wide Sodium Guidance 'Makes No Sense' in Most Countries

Shelley Wood

Sep 04, 2013AMSTERDAM — A new analysis from the large internationalPURE trial should intensify the ongoing debate over the link between sodium and blood pressure. Presenting PURE SODIUM here at the European Society of Cardiology (ESC) 2013 Congress, Dr Andrew Mente (McMaster University, Hamilton, ON) and colleagues found that only certain subgroups will actually experience blood-pressure benefits from restricting their sodium consumption. As such, sweeping recommendations for daily sodium limits are likely pointless in many parts of the world.

 "A targeted approach would be more appropriate for populations that consume a moderate amount of sodium in the 3-to-5-g/day range, because there would be very little benefit or a modest benefit of getting them down to low levels," Mente told heartwire . "For people who consume high amounts of sodium, it's important to get them down to moderate levels, so . . . a population-based approach would be more effective: you'd get better bang for the buck."

In one of the most striking findings in their study of almost 100 000 subjects, Mente and colleagues found that none of the populations surveyed had a "usual intake" of sodium that fell at or below the 2.3 g/day recommended in most guidelines.

A Dash of Data

Looking first at sodium and potassium intake, authors report that sodium intake was lowest in Malay; ranged from 4200 to 4800 mg/day in North America, Europe, South Asia, Africa, and South America; and spiked to more than 5500 mg/day in China. Potassium intake was highest in North America, Europe, and the Middle East and lowest in South Asia and Malay. Higher potassium consumption leads to greater excretion of sodium in the urine.

Next Mente and colleagues looked at the proportion of study participants whose sodium consumption fell within the recommended guidelines. Here, just 3.1% of subjects had observed sodium-intake levels below 2.3 g/day and less than 1% had levels below the recommended 1.5 g/day. When "usual intake was calculated, zero percent of subjects consumed less than 2.3 g/day and less than 1.5 g/day."

In line with previous observations, PURE SODIUM investigators found a linear relationship between BP and sodium levels, with both rising in parallel with one another. Potassium showed the inverse.

But critically, when the group looked at systolic blood pressure changes in response to 1-g increases in sodium consumption, they found that response to sodium was important only in certain groups: hypertensive subjects, the elderly, and people consuming more than 5 g/day of sodium.