TOO much salt is bad for you, but not eating enough might actually increase the risk of heart-related deaths.
A new Canadian study has found people with heart disease who consume low levels of salt -- the levels recommended in current sodium guidelines -- appear to be at higher risk of death from heart attacks, strokes and other cardiovascular causes than people who consume more moderate amounts of salt.
High sodium intake was associated with a higher risk of cardiovascular death compared to those with moderate salt intakes -- but only at levels higher than most Canadians eat.
Moderate salt intake, meanwhile -- amounts closer to Canadians' average daily consumption --was associated with the lowest risk.
The findings, published in the Journal of the American Medical Association, emphasize "the urgent need" to determine a safe range for sodium intakes, the team reports.
"The recommendations are almost that everybody should go down," said lead author Dr. Martin O'Donnell, an associate clinical professor of medicine at McMaster University in Hamilton, Ont.
Other studies have shown lowering salt intake from moderate levels leads to "modest reductions" in blood pressure, he said. "But there are no large randomized trials showing that it definitively prevents heart attacks and strokes.
"When you take people at more moderate intake levels, there is emerging uncertainty as to whether there are long-term benefits of reducing sodium intake further."
O'Donnell's team analyzed data from 28,880 people, including Canadians, who participated in two large trials conducted between 2001 and 2008 studying the effectiveness of high-blood pressure drugs. All were at high risk for heart attack, stroke or heart failure; most had coronary heart disease, diabetes or a cluster of other risk factors.
One of the challenges of any study looking at the risk of salt is how to measure sodium intake. Researchers can do it by asking people what they ate, but people might under- or over-report or forget something. It can also be difficult to estimate the sodium content of a person's diet.
An alternative is to measure how much sodium people excrete in their urine, because most of what we ingest is excreted in urine.
The researchers estimated 24-hour urinary sodium and potassium secretion based on an early morning fasting urine sample collected from patients at the start of the trials. After a median follow-up of 56 months, researchers looked at how many patients had had a heart attack, stroke, were admitted to hospital for heart failure or died from a cardiovascular cause. In all, more than 4,500 "cardiovascular events" occurred over the follow-up period.
-- Postmedia News