Too little salt may also pose health risk, second major study

Posted by AFN Staff Writers on 23rd November 2011

For years doctors have warned that too much salt is bad for your heart. Now, new research from the McMaster University, in Canada, suggests that both high and low levels of salt intake may put people with heart disease or diabetes at increased risk of cardiovascular complications.

This is the second major scientific study this month that has questioned the health benefits of reducing the dietary intake of sodium.

The study, published in the Journal of the American Medical Association (JAMA) today, found that moderate salt intake was associated with the lowest risk of cardiovascular events, while a higher intake of sodium was associated with an increased risk of stroke, heart attack and other cardiovascular events and a low intake was associated with an increased risk of cardiovascular death and hospitalisation for congestive heart failure.

The findings call into question current guidelines for salt intake, which recommend less than 2.3 grams (or 2,300 mg) per day.

The research was co-led by Dr. Martin O’Donnell, an associate clinical professor of medicine, and Dr. Salim Yusuf, a professor of medicine.

Dr O’Donnell said, “Our study is the first to report a J-shaped association between sodium intake and cardiovascular disease, which may explain why previous studies have found different results.”

For the McMaster study, the researchers examined 28,880 people at increased risk of heart disease from clinical trials conducted between 2001 and 2008.

The researchers estimated 24-hour urinary sodium and potassium excretion from a morning fasting urine sample. Follow-up found more than 4,500 cardiovascular events occurred, making this one of the largest studies examining the relationship between sodium excretion, as well as potassium excretion and cardiovascular events.

Dr O’Donnell added, “The current sodium intake guidelines are mostly based on previous clinical trials that found blood pressure is lowered modestly when sodium intake is reduced to this level (which was also found in the present study). However, there are no large studies looking at whether such low levels of sodium intake reduce the incidence of heart attacks and stroke.”