The American Heart Association (AHA) criticized a pooled analysis of prospective studies that found that low sodium intake was associated with an increased risk of death and major cardiovascular events in participants with or without hypertension.
The researchers said that high sodium intake was associated with an increased risk of cardiovascular events and death in participants with hypertension. However, there was no association for participants without hypertension.
Lead researcher Andrew Mente, PhD, of the Population Health Research Institute of McMaster University and Hamilton Health Sciences in Ontario, Canada, and colleagues published their results in The Lancet on May 20.
“These are extremely important findings for those who are suffering from high blood pressure,” Mente said in a news release. “While our data highlights the importance of reducing high salt intake in people with hypertension, it does not support reducing salt intake to low levels. Our findings are important because they show that lowering sodium is best targeted at those with hypertension who also consume high sodium diets.”
The AHA disputed the findings in a news release, writing that “the link between excessive sodium and high blood pressure – as well as higher risks of heart disease, stroke, heart failure and kidney disease – is indisputable.”
“The findings in this study are not valid, and you shouldn’t use it to inform yourself about how you’re going to eat,” AHA president Mark A. Creager, MD, said in a news release. “The large body of science clearly shows how excessive amounts of sodium in the American diet can cause high blood pressure, which can lead to heart disease, stroke, and even death.”
The researchers examined 133,118 people from 49 countries who enrolled in four prospective studies. Of the participants, 63,559 had hypertension and 69,559 did not have hypertension.
They found there was a 2.08 mm Hg increase in systolic blood pressure per 1 g sodium intake increase in participants with hypertension and a 1.22 mm Hg increase in systolic blood pressure per 1 g sodium intake increase in participants who did not have hypertension. The difference was statistically significant.
Of the participants with hypertension, sodium excretion of 7 g per day or more and less than 3 g per day were associated with an increased risk of death and major cardiovascular disease events compared with a sodium excretion of 4 to 5 g per day.
Of the participants without hypertension, higher sodium excretion was not associated with risk of the primary composite outcome compared with sodium excretion of 4 to 5 g per day. However, a sodium excretion of less than 3 g per day was associated with a significantly increased risk of death and major cardiovascular disease events.
“Low sodium intake reduces blood pressure modestly, compared to average intake, but low sodium intake also has other effects, including adverse elevations of certain hormones which may outweigh any benefits,” Mente said. “The key question is not whether blood pressure is lower with very low salt intake, instead it is whether it improves health.”