Cardiovascular 'Usual' Sodium Intake Seems to Hit Right Balance
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Friday, April 04, 2014 12:00 AM

A new analysis suggested that most people around the world are consuming just the right amount of sodium, although the American Heart Association questioned the findings.

Compared with an intake of 2,645 to 4,945 mg per day -- the usual sodium intake range for 90% of the world's population -- higher sodium consumption was associated with greater risks of all-cause mortality and cardiovascular disease events, but consuming too little sodium was tied to worse outcomes.   Compared with consuming less than 2,645 mg per day, usual intakes were associated with lower risks of death and cardiovascular disease events.

"The findings here lend support to those who have questioned the scientific basis for sodium reduction [recommendations], which are based primarily on the assumed blood pressure effect obtained in selected intervention studies and a selected meta-analysis of intervention studies," the authors wrote.

"However, the blood pressure effect is proportional to the baseline blood pressure, and because the baseline blood pressure in these intervention studies and the meta-analysis was much higher (approximately 130/85 mm Hg) than the mean blood pressure of the normotensive population (116/69 mm Hg) and the general population (122/71 mm Hg), the association of salt intake with blood pressure is overestimated," they continued. "Furthermore, the meta-analysis downplays other surrogate markers (hormones, lipids), which previously have been shown to increase during sodium reduction and thus have the potential to adversely affect outcomes."

The American Heart Association -- which recommends consuming less than 1,500 mg of sodium each day -- defended its stance.

"Given the abundance we have about excess sodium in diet and its relationship to hypertension and the ability of us as health professionals to recommend to patients that if they lower their blood pressure they will reduce their risk of heart disease and stroke, we are not distracted by these analyses [by the IOM] that have significant methodological flaws," said Elliott Antman, MD, a cardiologist at Brigham and Women's Hospital in Boston and president-elect of the AHA.

"There is a significant body of scientific research that proves a very dangerous association between sodium intake and significant health problems, including in some cases even death. I wish we could say sodium intake does not matter that much to your health, but it does," AHA CEO Nancy Brown said in a statement.

"Millions of Americans consume too much sodium and as a result face increased risk for high blood pressure, stroke, and other very serious conditions. Based on decades of scientifically sound research, we simply cannot minimize the impact of excess sodium in the diet," she continued, pointing out that about 90% of all U.S. adults will develop hypertension at some point.

In this study daily sodium intake was defined as low (less than 2,645 mg), usual (2,645 to 4,945 mg), or high (more than 4,945 mg).

The usual intake was based on prior data showing that sodium consumption fell within that range for 90% of the world's population.  Usual sodium intake was associated with lower risks of all-cause mortality and cardiovascular events compared with low intake, but there were no differences for stroke or heart disease.

High sodium intake was associated with greater risks of all-cause mortality, cardiovascular events, stroke, and heart disease compared with usual intake overall, although the stroke risk was significant only in Japanese populations.

When the researchers restricted their analyses to population-representative samples with adjustment for multiple confounders, the lower risk of all-cause mortality seen with usual versus low sodium intake remained significant. However high sodium intake was no longer associated with all-cause mortality when compared with usual intake.