August 13, 2014 - Blog
While too much salt in the diet has long been recognized as a serious health risk, new research has found eating too little may also pose health risks.
Two reports from a global collaborative study involving hundreds of investigators from 18 countries published in the New England Journal of Medicine are shaking up conventional wisdom around salt consumption.
The Prospective Urban & Rural Epidemiological (PURE) study, led by investigators from the Population Health Research Institute, McMaster University and Hamilton Health Sciences, followed more than 100,000 people for nearly four years. The study assessed sodium and potassium intake and related them to blood pressure as well as to deaths, heart disease and strokes.
Lead author of one report, Martin O’Donnell, suggests that what is now generally recommended as a healthy daily ceiling for salt consumption appears to be set too low.
“Low sodium intake does reduce blood pressure modestly, compared to moderate (or average) intake, but low sodium intake also has other effects, including adverse elevations of certain hormones that are associated with an increase in risk of death and cardiovascular diseases. The key question is whether these competing physiologic effects result in net clinical benefit or not," O’Donnell said, an associate clinical professor at McMaster University and National University of Ireland Galway.
“In the PURE study, we found the lowest risk of death and cardiovascular events in those who consumed moderate amounts of sodium intake (3 to 6 grams per day), with an increased risk above and below that range. While this finding has been reported in previous smaller studies, PURE is the largest international study to study sodium intake and health outcomes, and adds considerable strength to the contention that moderate sodium intake is optimal," he said.
Nevertheless, sodium consumption is still well above recommended amounts around the globe. In the United States, the average daily sodium intake for Americans ages 2 years and older is more than 3,400 mg—a number considerably high than the cap of 2,300 mg recommended for adults by the 2010 U.S. Dietary Guidelines for Americans.
Most of the sodium consumed comes from processed foods or foods prepared in restaurants. In fact, according to the Centers for Disease Control and Prevention (CDC), more than 40 percent of sodium intake comes from 10 types of foods, including breads, meat products, pizza, soups and sandwiches, among others. Add FDA’s recent announcement to set voluntary guidelines to reduce sodium in the food supply, and food and beverage manufacturers are feeling the heat to reduce sodium in their products. (For a closer look at sodium in the food supply, check out this free FoodTech Toolbox report, “Reducing Sodium in the Food Supply: A Journey in Progress.")
This is, of course, is because high-sodium diets are associated with adverse health effects, such as heart disease and stroke.
Researchers have shown that the effects of increasing sodium intake on raising blood pressure—a risk factor for heart attack, heart failure, stroke and other problems—become dramatically worse as intake rises above 5 grams per day, especially among people who already have high blood pressure, or who are older than 55, or both.
But the blood-pressure effects are more modest at average levels of sodium consumption (3 to 5 grams per day) and not evident at low levels of intake below 3 grams of sodium per day (a level that is higher than the maximum currently recommended by many guidelines), said Andrew Mente, lead author of another report, and an assistant professor of clinical epidemiology and biostatistics.
“While there has been much focus on reducing salt in the diet, an important and ignored approach to lowering blood pressure is increasing the amount of potassium consumed. A balanced approach is what is likely to have the greatest benefit in lowering blood pressure," Mente said. “This can be achieved by moderation in salt intake, combined with eating lots of fruits and vegetables."
Taken together, the papers show there is a “sweet spot" for sodium consumption, where too much or too little can be damaging, while a moderate amount between 3 and 6 grams is optimal.
“The findings of both studies are robust, globally applicable and collectively question established dogma and recommended policies. This also means that salt reduction should be primarily targeted at those who have high BP and those who consume a lot of salt." said Salim Yusuf, principal investigator, PURE study, senior author of both reports, and director, Population Health Research Institute, which designed and coordinated the study.
While too much salt in the diet has long been recognized as a serious health risk, new research has found eating too little may also pose health risks.
Two reports from a global collaborative study involving hundreds of investigators from 18 countries published in the New England Journal of Medicine are shaking up conventional wisdom around salt consumption.
The Prospective Urban & Rural Epidemiological (PURE) study, led by investigators from the Population Health Research Institute, McMaster University and Hamilton Health Sciences, followed more than 100,000 people for nearly four years. The study assessed sodium and potassium intake and related them to blood pressure as well as to deaths, heart disease and strokes.
Lead author of one report, Martin O’Donnell, suggests that what is now generally recommended as a healthy daily ceiling for salt consumption appears to be set too low.
“Low sodium intake does reduce blood pressure modestly, compared to moderate (or average) intake, but low sodium intake also has other effects, including adverse elevations of certain hormones that are associated with an increase in risk of death and cardiovascular diseases. The key question is whether these competing physiologic effects result in net clinical benefit or not," O’Donnell said, an associate clinical professor at McMaster University and National University of Ireland Galway.
“In the PURE study, we found the lowest risk of death and cardiovascular events in those who consumed moderate amounts of sodium intake (3 to 6 grams per day), with an increased risk above and below that range. While this finding has been reported in previous smaller studies, PURE is the largest international study to study sodium intake and health outcomes, and adds considerable strength to the contention that moderate sodium intake is optimal," he said.
Nevertheless, sodium consumption is still well above recommended amounts around the globe. In the United States, the average daily sodium intake for Americans ages 2 years and older is more than 3,400 mg—a number considerably high than the cap of 2,300 mg recommended for adults by the 2010 U.S. Dietary Guidelines for Americans.
Most of the sodium consumed comes from processed foods or foods prepared in restaurants. In fact, according to the Centers for Disease Control and Prevention (CDC), more than 40 percent of sodium intake comes from 10 types of foods, including breads, meat products, pizza, soups and sandwiches, among others. Add FDA’s recent announcement to set voluntary guidelines to reduce sodium in the food supply, and food and beverage manufacturers are feeling the heat to reduce sodium in their products. (For a closer look at sodium in the food supply, check out this free FoodTech Toolbox report, “Reducing Sodium in the Food Supply: A Journey in Progress.")
This is, of course, is because high-sodium diets are associated with adverse health effects, such as heart disease and stroke.
Researchers have shown that the effects of increasing sodium intake on raising blood pressure—a risk factor for heart attack, heart failure, stroke and other problems—become dramatically worse as intake rises above 5 grams per day, especially among people who already have high blood pressure, or who are older than 55, or both.
But the blood-pressure effects are more modest at average levels of sodium consumption (3 to 5 grams per day) and not evident at low levels of intake below 3 grams of sodium per day (a level that is higher than the maximum currently recommended by many guidelines), said Andrew Mente, lead author of another report, and an assistant professor of clinical epidemiology and biostatistics.
“While there has been much focus on reducing salt in the diet, an important and ignored approach to lowering blood pressure is increasing the amount of potassium consumed. A balanced approach is what is likely to have the greatest benefit in lowering blood pressure," Mente said. “This can be achieved by moderation in salt intake, combined with eating lots of fruits and vegetables."
Taken together, the papers show there is a “sweet spot" for sodium consumption, where too much or too little can be damaging, while a moderate amount between 3 and 6 grams is optimal.
“The findings of both studies are robust, globally applicable and collectively question established dogma and recommended policies. This also means that salt reduction should be primarily targeted at those who have high BP and those who consume a lot of salt." said Salim Yusuf, principal investigator, PURE study, senior author of both reports, and director, Population Health Research Institute, which designed and coordinated the study.
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