For most people, the amount of salt they eat is not harmful, according to a new controversial study.
Health guidelines in the United States and the United Kingdom say that more than 0.75 teaspoons a day increase your risk of having a heart attack.
But the new study from McMaster University in Ontario found that any amount less than two and a half tablespoons (five grams), which is standard for most people, is safe.
And for those who eat too much, they can balance the health risk if they eat lots of fruits, vegetables and other foods rich in potassium.
The authors suggest that public health campaigns that urge people to reduce their sodium intake may be necessary in countries such as China that consume more salty foods, but may be unnecessary in most of Europe and North America.
The guidelines say do not eat more than 0.75 teaspoons of salt per day. But a study from McMaster University found that anything below two and a half teaspoons, which is standard for most people, is safe.
"There is no convincing evidence that people with moderate or average sodium intake need to reduce their sodium intake for the prevention of heart disease and stroke," said lead author Martin O & Donnell, associate professor of clinical medicine. .
The study conducted by the Population Health Research Institute (PHRI) of McMaster University in Ontario followed 94,378 people, aged 35 to 70, for an average of eight years in 18 countries.
He discovered that there was an associated risk of cardiovascular disease and stroke only when the average intake is greater than five grams of sodium per day.
Those who consumed more than 7 g per day had an increased risk of cardiovascular events and mortality in people with high blood pressure.
And the low sodium content below 3 g per day was associated with an increased risk of cardiovascular events and mortality in people with or without hypertension.
But there is good news even for those who consume large amounts of salt, since any health risk from sodium intake is virtually eliminated if they improve the quality of their diet by adding fruits, vegetables, dairy products, potatoes and other rich foods. in potassium
In China, more than four fifths exceeded this, but in other countries most had an average sodium intake of three to five grams per day.
The study found that the highest sodium intake was associated with an increase in blood pressure and a higher incidence of stroke, but this was found mainly in countries like China with a very high sodium intake and not in others.
Higher sodium intake was associated with lower rates of myocardial infarction and total mortality.
"The World Health Organization recommends consuming less than two grams of sodium, that is, one teaspoon of salt, per day as a preventive measure against cardiovascular diseases, but there is little evidence as to better health outcomes that individuals achieve at this time. low level, level, "said associate professor Andrew Mente.
"Only in the communities with the highest sodium intake (those of more than five grams per day of sodium), mainly in China, do we find a direct link between sodium intake and the main cardiovascular events such as myocardial infarction and stroke.
"In the communities that consumed less than five grams of sodium a day, the opposite happened.
"Sodium intake was inversely associated with myocardial infarction or heart attacks and total mortality, and stroke did not increase."
In addition, the rates of stroke, cardiovascular death, and total mortality decreased with increasing potassium intake in these communities.
Diets rich in fruits and vegetables are rich in potassium, but it is not known if potassium itself is protective, or if it could simply be a marker of a healthy diet.
Dr. Mente said: "We found that all the major cardiovascular problems, including death, decrease in communities and countries where there is an increased consumption of potassium found in foods such as fruits, vegetables, dairy products, potatoes, nuts and beans. .
"Our study adds to the growing evidence to suggest that, with a moderate intake, sodium may have a beneficial role in cardiovascular health, but a potentially more harmful role when intake is very high or very low.
& # 39; This is the relationship we would expect for any nutrient and essential health.
"Our bodies need essential nutrients like sodium, but the question is how much."
"The recommendation to reduce sodium intake to 2 g / day is based on short-term tests of sodium intake and blood pressure, and the assumption that any approach to reduce blood pressure will necessarily translate into lower risk of cardiovascular disease without unforeseen consequences.
"While low sodium intake lowers blood pressure, at very low levels it can also have other effects, including adverse elevations of certain hormones associated with an increased risk of death and cardiovascular disease."
The study was published in The Lancet.
Commenting on the study, Franz Messerli and Louis Hofstetter of University Hospital, Bern and Sripal Bangalore of the Faculty of Medicine of the University of New York said that two years ago Dr. Mente and his colleagues said that salt restriction reduced the risk of heart disease, stroke or death alone in patients had high blood pressure and salt restriction could be harmful if the consumption of salt was too low. But his critics called it "bad science."
The new study added that "there is little doubt that, with the notable exception of the benefits of increased potassium intake, the findings of Mente and his colleagues will again generate controversy."