Moderate salt intake appears to be linked to the lowest risk of heart disease, while high sodium levels were associated with increased risk of heart attack and stroke, and low levels were linked to cardiovascular death and hospitalization for congestive heart failure.
"Consume less than 1,500 mg of sodium daily unless your doctor suggests otherwise."
Dr. Martin O'Donnell, an associate clinical professor of medicine at McMaster University in Canada, noted that previous observational studies had found a link between sodium and heart disease and stroke, and said that the research had proved controversial. He said his study is the first to fine a J-shaped association between sodium intake and cardiovascular disease, possibly explain why previous studies indicated different findings.
During the study researchers examined 28,880 patients at increased risk of heart disease from clinical trials conducted between 2001 and 2008. Using a fasting urine sample, investigators estimated 24-hour urinary sodium and potassium excretion.
They found during follow up that 4,500 cardiovascular events had occurred. Statistical analysis was utilized to calculate the association between urinary sodium and potassium with cardiovascular events.
As compared to moderate sodium excretion of between 4,000 to 5,990 milligrams daily, investigators discovered that sodium excretion of more than 7,000 milligrams a day was associated with an increased risk of all cardiovascular events, while excretion of less than 3,000 milligrams daily was linked to increased risk of cardiovascular death or congestive heart failure hospitalization.
The finding calls into question Canada's current daily sodium recommendations of less than 2,300 milligrams daily. The American Heart Association suggests that most Americans, especially those with high blood pressure, consume less than 1,500 milligrams of sodium daily.
Investigators clarifying the optimal daily intake is especially important for patients with existing heart disease since they could be vulnerable to sodium levels that are too low or too high. They suggested that large clinical trials will be needed to determine whether individuals who consume moderate amounts of sodium would benefit from consuming less.
The study was recently published in the Journal of the American Medical Association.