The findings from a team at the US Centers for Disease Control and Prevention are a counterpoint to a fiercely-debated study released last week that found no evidence that small cuts in salt intake lower the risk of heart disease and premature death.
"Salt is still bad for you," said Dr Thomas Farley, Health Commissioner for New York City, which is leading a campaign to reduce salt in restaurant and packaged foods by 25% over five years.
Most health experts agree with him.
High salt diet 'risky'
The CDC study, published in the Archives of Internal Medicine, specifically focused on growing research that shows that a diet high in salt and low in potassium is especially risky. Dr Farley, who wrote an editorial on the CDC study, said it was one of the best yet to look at the long-term effects of eating too much salt.
"It is entirely consistent with what we've said all along about sodium intake," Dr Farley said.
For the study, researchers looked at the long-term effects of sodium and potassium intake as part of the Third National Health and Nutrition Examination Survey (NHANES), a 15-year study of more than 12,000 people.
People who had a high salt intake and a low potassium intake were most at risk.
That group had a 50% increased risk of death from any cause, and about a 200% increase in risk of cardiac death, said Dr Elena Kuklina of the CDC.
She said consumers need to increase the levels of potassium in their diet by adding more servings of fresh fruits and vegetables, such as spinach, grapes, carrots, sweet potatoes, and low fat milk and yoghurt.
Confusion about salt guidelines
The Salt Institute, an industry group, challenged the findings, pointing out that the CDC study found that the link between salt intake and heart disease was statistically insignificant.
"This is a highly flawed publication that reveals more about the anti-salt agenda being pursued by the CDC than about any relationship between salt and health," said Mort Satin, the Salt Institute's Director of Science and Research.
"The only significance is between low potassium and mortality," Satin said in a statement.
Dr Robert Briss, director of the National Center for Chronic Disease Prevention and Health Promotion at the CDC, said the findings support the general weight of evidence and suggests that higher doses of sodium are linked with poor health consequences.
Dr Kuklina said potassium often counteracts the effects of salt in the diet. This equilibrium is affected when people eat highly processed foods, which tend to increase sodium levels and decrease potassium content.
Instead of focusing only on salt, Dr Kuklina said researchers should focus on the balance between potassium and salt.
"We need to strive to do both – decrease your sodium intake and increase your potassium intake," she said.
(Reuters Health, Julie Steenhuysen, July 2011)