This finding is important because it raises questions about whether someone with an average American intake of about 3,000 milligrams of sodium a day would benefit from making any reduction, Nissen said. More and better investigations should be done to determine if someone with high blood pressure would be helped or harmed by the current recommendation, he added.
It could be that subjects with low sodium intake in studies have health problems that skewed the results in the Irish study and others, according to Alice H. Lichtenstein, the director of the Cardiovascular Nutrition Laboratory at Tufts University and an AHA spokeswoman.
“When we looked at studies for the National Institutes of Medicine, we couldn’t rule out the strong possibility that people with lower sodium intake were sicker subjects and had a greatly diminished food intake in general, and might have been misreporting their intake,” she said.
But Lichtenstein admitted that, while the data supports lowering sodium intake down to about 2,300 milligrams daily, there isn't yet much evidence for going down to 1,500. Like Nissen, she said there needs to be more research to get a definitive answer.
The consumer advocacy group, Center for Science in the Public Interest, said in a statement it believes there is not enough evidence to change the current salt recommendations.
"There is a near-global scientific consensus that most people consume too much salt, largely from packaged and restaurant foods," said Bonnie Liebman, CSPI's director of nutrition. "Given that two out of three American adults has either hypertension or prehypertension, it would be foolish to reverse that advice based on recent flawed studies."
Those sodium intake guidelines, followed by millions of Americans, were recently scrutinized by a panel of health and nutrition experts known as the “2015 Dietary Guideline Advisory Committee” with an eye towards possible revision.
But Nissen said he doesn’t expect the recommendations to change any time soon.
“These ideas are so entrenched it will be difficult to get people to let go of such long held beliefs,” he said.