IOM report questions steep cuts in salt intake

Maintaining moderation in sodium consumption is key, according to a new Institute of Medicine report (PDF) that supported past research and reiterated that high salt intake could cause heart disease, but which also warned that reducing salt intake below recommended dietary guidelines could be harmful.

The average American adult consumes 3,400 mg of sodium a day, while current dietary guidelines recommend Americans consume 2,300 mg a day. Researchers said Tuesday that their evidence reiterated that high sodium intake increases the risk of cardiovascular disease. However, researchers also said there isn't enough evidence to conclude that lowering sodium consumption to less than 2,300 mg would positively or negatively affect the risk of suffering a stroke or dying from heart disease.

Some have advised groups susceptible to heart problems—including people 51 or older, diabetes sufferers, and African Americans—to decrease their salt intake to 1,500 mg a day, which is the suggestion for the general public from the American Heart Association. Researchers said Tuesday that their work does not support that these subgroups should be treated any differently than the general population.

“Thus, the committee concluded that the evidence on direct health outcomes does not support recommendations to lower sodium intake within these subgroups to, or even below, 1,500 mg,” according to the report.

The report's conclusion is two-fold, said Brian Strom, chair of the IOM's research committee and a professor at the University Of Pennsylvania Perelman School Of Medicine. The committee supports a reduction in high-salt diets but lacks definitive answers, as more research is needed.

“Changes in diet are more complex than simply changing a single mineral. More research is needed to understand these pathways,” Strom said in a news release.

A low-sodium diet could be harmful to those with mid- to late-stage heart failure who are undergoing aggressive treatment. The research didn't include a recommendation for salt intake, as the IOM didn't charge them with coming up with a suggestion.

The report, released Tuesday, calls for additional research and revisits an IOM report from eight years ago. In 2005, researchers said adults should consume 1,500 mg of salt for an “adequate diet,” Strom recalled.

Critics have attacked the restaurant and food industry for serving salty foods and loading processed products with sodium. A study released Monday in JAMA Internal Medicine logged the sodium levels in foods from 2005 to 2011 and cited that 80% of sodium consumed by Americans was via food manufacturers and restaurants. That study concluded that sodium levels stayed the same over those six years.

“Based on our sample, reductions in sodium levels in processed and restaurant foods are inconsistent and slow,” according to the JAMA Internal Medicine study.

Strom said he hopes hospital executives—and the general public—have a good understanding of the science in which researchers used to base their conclusions.

“All the prior recommendations have been based on blood pressure,” he said. “Our focus was on heart outcomes rather than blood pressure.”

The Salt Institute has kept a close eye on the report, as the lobby group has blasted past research calling for sodium reductions. The group has asked for better research in the past, and on Tuesday said it welcomed the IOM's conclusions: “We hope (the report) will be a first step in an extended process correcting much of the one-sided myth-information on the subject of salt and health,” Morton Satin, the Salt Institute's vice president of science and research, said in a statement.

Follow Ashok Selvam on Twitter: @MH_aselvam