A new study out of Canada's McMaster University suggests that low-salt diets might not be as healthy as we thought and may, in fact, increase the risk of cardiovascular disease (CVD) and death in comparison to diets with average salt intake. Furthermore, the findings suggest that those with high blood pressure are the only individuals that should worry about reducing sodium intake.
The team examined over 130,000 people from 49 countries and focused on the nature of the relationship between salt intake and death, heart disease and stroke in people with both high blood pressure and low blood pressure. The results revealed that in both groups, low-salt diets were connected to more heart attacks, strokes and deaths compared to those with average salt intake in their diet.
"These are extremely important findings for those who are suffering from high blood pressure," said Andrew Mente of McMaster University and lead author of the study. "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," he added.
Although some guidelines recommend that sodium intake should be lowered to 2.3 grams per day from the current standard intake of 3.5 to four grams per day, the new data suggests that consuming less than three grams of salt per day can lead to health risks regardless of a person's blood pressure.
"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."
Interestingly, the team also found that although low salt intake can be unsafe after a certain point, high levels of salt intake only lead to dangers in those with hypertension.
"This study adds to our understanding of the relationship between salt intake and health, and questions the appropriateness of current guidelines that recommend low sodium intake in the entire population," added Martin O'Donnell of McMaster University and co-author of the study.
"An approach that recommends salt in moderation, particularly focused on those with hypertension, appears more in-line with current evidence," he added.
The findings were published in the May 20 issue of the journal The Lancet.