HAMILTON, ONT. — A study that appeared online Aug. 9 in The Lancet questions current recommended sodium intake limits. Heart health risk increased in people who ate more than 5 grams a day, but fewer than 5% of people in developed countries exceed that level, according to the study.

Five grams a day is more than twice as much as the daily sodium limits recommended by the World Health Organization (2 grams) and the Dietary Guidelines for Americans 2015-2020 (2.3 grams). The American Heart Association recommends no more than 2.3 grams per day with an ideal limit of 1.5 grams per day for most adults, especially those with high blood pressure.

 “The World Health Organization recommends consumption of less than 2 grams of sodium — that’s one teaspoon of salt — a day as a preventative measure against cardiovascular disease, but there is little evidence in terms of improved health outcomes that individuals ever achieve at such a low level,” said Andrew Mente, Ph.D., an author of the study and a researcher at the Population Health Research Institute of McMaster University in Hamilton.

Scientists from the P.H.R.I. of McMaster University and Hamilton Health Sciences carried out the research along with other researchers from 21 countries.

The study followed 94,000 people from the ages of 35 to 70 for an average of eight years in communities from 18 countries. An associated risk of cardiovascular disease and strokes was found only when the average intake was greater than 5 grams of sodium per person per day. China was the only country in the study where 80% of communities had a sodium intake of greater than 5 grams a day. An average sodium consumption of 3 to 5 grams per day was found in a majority of communities.

“Only in the communities with the most sodium intake, those over 5 grams a day of sodium, which is mainly in China, did we find a direct link between sodium intake and major cardiovascular events like heart attack and stroke,” Dr. Mente said. “In communities that consumed less than 5 grams of sodium a day, the opposite was the case. Sodium consumption was inversely associated with myocardial infarction or heart attacks and total mortality, and no increase in stroke.”

Any health risk of sodium intake virtually is eliminated if people improve their diet by adding fruit, vegetables, dairy foods, potatoes and other potassium-rich foods, according to the study.

The study was funded by the P.H.R.I., the Canadian Institutes of Health Research, the Heart and Stroke Foundation of Ontario and the European Research Council as well as unrestricted grants from several pharmaceutical companies and grants from health agencies or ministries of 18 countries.

The information for the research came from the international Prospective Urban Rural Epidemiology study run by the P.H.R.I. The research involved individual and community information from Argentina, Bangladesh, Brazil, Chile, China, Colombia, India, Iran, Malaysia, occupied Palestinian territory, Pakistan, Philippines, Poland, Saudi Arabia, South Africa, Sweden, Tanzania, Turkey, United Arab Emirates and Zimbabwe.