For the past century people with weak hearts have been told to lower their salt intake, but until now there has been little scientific evidence behind the recommendation.
Results from the largest randomized clinical trial, called SODIUM-HF, to look at sodium reduction and heart failure, conducted by researchers from the University of Alberta, were mixed.
Though reducing salt intake did not lead to fewer emergency visits, hospitalizations or deaths for patients with heart failure, the researchers did find an improvement in symptoms such as swelling, fatigue and coughing, as well as better overall quality of life.
“We can no longer put a blanket recommendation across all patients and say that limiting sodium intake is going to reduce your chances of either dying or being in hospital, but I can say comfortably that it could improve people's quality of life overall,” said the study’s lead author.
About the trial
The researchers followed 806 patients at 26 medical centers in Canada, the United States, Columbia, Chile, Mexico and New Zealand. All were suffering from heart failure, a condition in which the heart becomes too weak to pump blood effectively.
Half of the study participants were randomly assigned to receive usual care, while the rest received nutritional counseling on how to reduce their dietary salt intake.
Patients in the nutritional counseling arm of the trial were given dietitian-designed menu suggestions using foods from their own region and were encouraged to cook at home without adding salt and to avoid high-salt ingredients. Most dietary sodium comes from processed foods and restaurant meal, not the salt-shaker.
The target sodium intake was 1,500 milligrams per day — or the equivalent of about two-thirds of a teaspoon of salt — which is daily requirement for adults ages 19 to 50.
Before the study, patients consumed an average of 2,217 mg per day, or just under one teaspoon.
After one year of study, the usual care group consumed an average of 2,072 mg of sodium daily, while those who received dietitian counselling consumed 1,658 mg per day.
The researchers compared rates of death from any cause, cardiovascular hospitalization and cardiovascular emergency department visits in the two study groups but found no statistically significant difference.
They did find consistent improvements for the low-sodium group using three different quality of life assessment tools, as well as a measure of heart failure severity.
The lead researcher said that he will continue to advise heart failure patients to cut back on salt, but now he will be clearer about the expected benefits.
Source: The Lancet, April 2, 2022.
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