A new study illustrates how lowering sodium intake can benefit heart failure patients
People with weak hearts have been told to cut back on their salt intake for more than a century, but there has been no scientific evidence to back this up until now.
There were mixed results from the largest randomized clinical trial on sodium reduction and heart failure that was published in The Lancet and presented at the 71st Annual Scientific Session of the American College of Cardiology on Saturday and Sunday, but they were still good news.
Although lowering salt intake did not result in fewer emergency visits, hospitalizations, or deaths in heart failure patients, the researchers did see an improvement in symptoms including edema, weariness, and coughing, as well as a higher overall quality of life.
“We can no longer say that limiting sodium intake will reduce your chances of dying or being hospitalized,” said lead author Justin Ezekowitz, professor in the University of Alberta’s Faculty of Medicine and Dentistry and co-director of the Canadian VIGOUR Centre.
A total of 806 patients were studied at 26 medical centers in Canada, the United States, Columbia, Chile, Mexico, and New Zealand. All of them had heart failure, a condition in which the heart becomes too weak to adequately pump blood. Half of the people who took part in the study were chosen at random to get normal treatment, while the other half got nutritional advice on how to cut back on their salt intake.
Patient-designed menu options using foods from their own region were given to patients in the nutritional counseling arm of the experiment, and they were advised to cook at home without adding salt and to avoid high-salt components. Instead of being shook at the table, most dietary sodium is buried in processed foods or restaurant meals, according to Ezekowitz.
“Anything in a bag, a box, or a can generally has more salt in it than you would expect,” said Ezekowitz, who is also a cardiologist at the Mazankowski Alberta Heart Institute and head of the University of Alberta’s Cardiovascular Research Institute.
The daily sodium intake target was 1,500 milligrams, or about two-thirds of a teaspoon of salt, which is the Health Canada recommended limit for most Canadians, whether or not they have heart failure.
Patients consumed an average of 2,217 mg per day before the trial, or just under one teaspoon. After a year of research, the normal care group ate an average of 2,072 mg of salt a day, while the nutritional guidance group ate 1,658 mg, which is about a quarter teaspoon of salt less a day, on average.
There were no statistically significant differences between the two groups when they looked at their rates of death from any cause, cardiovascular hospitalization, and visits to the emergency room for cardiovascular problems; this was true for both groups.
New York Heart Association heart failure classification, which is a measure of heart failure severity, showed that the low-sodium group had a better quality of life than those who ate more salt.
Ezekowitz said he will continue to counsel heart failure patients to limit their salt intake, but he will be more specific about the benefits. He wants doctors to think about changing their patients’ diets as a way to help them.
The researchers will do additional research to identify a signal in the blood of patients who benefited the most from the low-sodium diet, with the goal of providing more tailored individual diet prescriptions in the future. The researchers will also follow up with the trial subjects at 24 months and five years to see whether there are any long-term advantages.