Could a low sodium diet sometimes do more harm than good?
People with heart failure have been told to pay special attention to their sodium intake.
ISLAMABAD, (Online) - Salt is composed of about 40% sodium and 60% chloride. A small quantity of sodium is needed by the body to conduct nerve impulses, contract and relax muscles, and maintain the proper balance of water and minerals.
However, eating too much sodium is linked with an increased risk of developing high blood pressure, which is a leading cause of stroke and heart disease.
The Dietary Guidelines for Americans recommend that adults consume less than 2,300 mg of sodium per day, which is equal to about 1 teaspoon of table salt.
However, according to the CDC, Americans consume more than 3,400 mg of sodium each day, on average. Many people unknowingly consume high quantities of salt through processed foods, particularly bread, meats and sauces.
Historically, people with heart failure have been told to pay special attention to their sodium intake to manage their condition. In 2010, the Heart Failure Society of America recommended a daily sodium intake lower than 2,000 mg for patients with moderate to severe heart failure symptoms.
Yet there is an ongoing debate on the usefulness of dietary sodium restriction in heart failure.
A clinical trial published in 2013 found that a low-sodium diet may protect against disease progression in those diagnosed with heart failure.
However, a more recent clinical trial in heart failure patients (the Sodium-HF trial), found that reducing sodium intake did not reduce clinical events.
The 2022 guidelines from the American Heart Association/American College of Cardiology/Heart Failure Society of America recommend “avoiding excessive sodium intake” to reduce symptoms in patients with stage C heart failure, but they do not suggest a specific restriction.
Now, Anirudh Palicherla, MBBS, and his coworkers at Creighton University School of Medicine, carried out a meta-analysis of randomized clinical trials comparing low dietary sodium to usual care in heart failure patients.
The meta-analysis was presented at the American College of Cardiology Congress.
Is too little salt a thing?
Dr. Palicherla’s team searched multiple databases for randomized clinical trials comparing low dietary sodium to usual care in heart failure patients.
The meta-analysis included a total of nine studies with 3,499 patients. Compared to usual care, the sodium restriction group showed a significant increase in in-hospital mortality (risk ratio [RR] 1.84; 95% confidence interval [CI] 1.46-2.31; P<0.001), while there was no significant difference in hospitalization between the two groups (RR 1.45,95%CI; 0.99-2.11; P=0.05).
Based on the results of the meta-analysis, the researchers concluded that sodium restriction in patients with heart failure resulted in increased mortality.
“In absence of benefit of salt restriction and increased harm, there should be a reconsideration of such recommendations,” they note.
Verifying previous research
Several experts expressed their criticism of the review to Medical News Today because it included studies that had been withdrawn for lack of verification.
Dr. Lawrence J. Appel, the C. David Molina professor of medicine and director of the Welch Center for Prevention, Epidemiology and Clinical Research at Johns Hopkins University, told MNT:
“There is a huge problem with this meta-analysis [because] it relies on four trials done by a single group in Italy (the Paterna and Parrinello studies) [t]here has been substantial concern about [their] research integrity, with numerous irregularities as well as manuscript retractions.”
“Note that another meta-analysis of these studies was retracted [because] the raw data from the investigators could not be produced. By no means should the results of this [meta-analysis] guide policy,” he said.
Dr. Frank M. Sacks, professor of cardiovascular disease prevention at Harvard T.H. Chan School of Public Health, expressed the same concerns:
“Problem is that a meta-analysis is only as good as its component studies. There are serious problems with some of the individual studies, such as [the] Paterna [study]. What’s more, Paterna had the large majority of events, so the results of the meta-analysis are largely produced by Paterna.”
Some patients may benefit more
Graham MacGregor, CBE, professor of cardiovascular medicine at the Wolfson Institute, Queen Mary University of London, was also critical of the inclusion of retracted studies in the meta-analysis.
“Heart failure patients are on diuretics that deplete patients of sodium, so you need to be very careful,” he noted.
Last year, Justin A. Ezekowitz, MBBCH, cardiology professor and director of cardiovascular research at the University of Alberta, published a similar meta-analysisTrusted Source together with his coworkers.
They concluded that sodium restriction was not associated with fewer deaths or hospitalizations in patients with heart failure, but may be associated with improvements in symptoms and quality of life.
When asked to comment about the new meta-analysis by Dr. Palicherla, Dr. Ezekowitz told MNT that “it is a very complex area” and he would need to look closer at the methods of the meta-analysis in order to establish the validity of their findings.
“Nevertheless, the area is in need of further [randomized clinical trials] to outline which patients may benefit more (or less) from a strategy of dietary sodium restriction. Either way, the U.S. and international guidelines will need to take our meta-analysis and the SODIUM-HF trial into account when updating the guidelines,” Dr. Ezekowitz added.
Tips for a heart-healthy diet
Experts recommend the following suggestions to monitor salt intake in people with heart disease:
• Keep an eye on sodium on nutritional labelsTrusted Source
• Consider using potassium chloride instead of sodium chloride: Substituting common salt with potassium chloride offers flavor and reduces sodium intake. According to FDA guidanceTrusted Source, “this may help to reduce the intake of sodium, which is over-consumed by the US population, while increasing potassium, which is under-consumed.”
• Follow the DASH diet: The DASH (Dietary Approaches to Stop Hypertension) diet is an eating plan that focuses on the consumption of a variety of nutrient-rich foods, including fruits, vegetables, whole grains and low-fat dairy products, and limits the intake of salt, sugar and high-fat products. The DASH diet was designed to help treat or prevent high blood pressure (hypertension) but has also shown other benefits.