A large international study questions the conventional wisdom that most people should cut back on salt, suggesting that the amount most folks consume is OK for heart health – and too little may be as bad as too much.
The findings came under immediate attack by other scientists.
Limiting salt is still important for people with high blood pressure – and in fact, a second study estimates that too much sodium contributes to up to 1.65 million deaths each year.
Both studies have strengths and weaknesses, and they come as the U.S. government prepares to nudge industry to trim sodium in processed and restaurant foods.
The first study’s leader, Dr. Salim Yusuf of McMaster University’s Population Health Research Institute in Hamilton, Ontario, urged keeping an open mind.
There are those, who have made a career out of promoting extreme sodium reduction, that will attack us, he said. It’s better to focus on healthy lifestyles and overall diets instead of a single element, and that is something everyone can rally around.
No one should view this as permission to eat more salt, he said, adding that most people should stay where they are.
The studies are in today’s New England Journal of Medicine.
Yusuf’s study is observational, rather than a strict experiment, and has big limitations in its methods. But its size lends strength – more than 100,000 people in 17 countries, the largest on this topic. It’s also from a general population, not just people at high risk of heart disease, as many past studies have been.
Sodium levels generally correlate with the risk of high blood pressure. The link is strongest when sodium intake is high and wasn’t seen at all when consumption is low. The link is stronger as people age.
Potassium, found in vegetables and fruits, seems to lower blood pressure and heart risks and offsets sodium’s effect.
People who consume 3 to 6 grams of sodium a day (about 8 to 15 grams of salt) had the lowest risk of heart problems or death from any cause. More or less sodium raised risk. Americans average roughly 4 grams a day.
Dr. Martin O’Donnell of McMaster University, one of the researchers, said potatoes, bananas, avocados, leafy greens, nuts, apricots, salmon and mushrooms are high in potassium, and it’s easier for people to add things to their diet than to take away salt.
The Food and Drug Administration is preparing voluntary guidelines asking industry to trim sodium in processed foods, the main source in the diet.
The totality of the evidence strongly supports limiting sodium, said Dr. Elliott Antman, a Brigham and Women’s Hospital cardiologist and president of the Heart Association.
He says his organization feels now is the time for action and not hesitation anymore.