Endocrinologist responds to study suggesting low sodium intake may increase cardiovascular events

In May, a study in The Lancet suggested that patients who had a low sodium intake had an increased risk of death and major cardiovascular events.

The researchers added that patients with hypertension who had a high sodium intake had an increased risk of those outcomes, but patients without hypertension did not have an increased risk if they had a high sodium intake.

The American Heart Association (AHA) responded by issuing a news release that said evidence had shown that people who have excessive sodium in their diet have an increased risk of high blood pressure, heart disease, stroke, heart failure and kidney disease.

Naomi Fisher, MD, an endocrinologist at Brigham and Women’s Hospital in Boston and an associate professor at Harvard Medical School, agreed with the AHA that The Lancet study had flaws.

Fisher wrote a post on Harvard Medical School’s health blog and noted that the researchers argued moderate intake of sodium, approximately 4 to 5 grams daily, was the ideal amount. However, the FDA sets its upper limit at 2.3 grams of sodium per daily, while the AHA sets its upper limit as 1.5 grams of sodium per day. She noted that the average American eats 4 grams of sodium per day.

Fisher added that The Lancet researchers only examined one 24-hour urine collection from each participant, which she wrote “resulted in a poor estimation of everyone’s daily intake of sodium.” She mentioned that it would be preferable to collect urine for 24 hours on multiple days during an extended period of time.

Further, she noted that the study might have been subject to “reverse causality” bias because participants were at risk for or diagnosed with high blood pressure, diabetes or other conditions. She wrote that the participants might have eaten less sodium or food because of their diagnoses or health concerns.

“Debates are healthy, but this one should not distract us from the reality that only a tiny fraction of our population eats a low sodium diet,” Fisher wrote. “Most of us are eating far too much sodium. It may well be that low sodium diets are harmful for small subsets of people, but for the majority it will take more convincing evidence to change current efforts at salt restriction.”