Study: Salt not as harmful to health as previously thought
![Salt substitutes are associated with a reduced risk of high blood pressure without increasing the risk of low blood pressure, according to new findings published in the Journal of the American College of Cardiology.[1]](/sites/default/files/styles/top_stories/public/2018-04/salt-3285024_1920.jpg.webp?itok=cA0aeCky)
Sodium intake is associated with cardiovascular disease (CVD) only in communities where the average intake is more than five grams per day, according to an update of the Prospective Urban Rural Epidemiology (PURE) study published in The Lancet.
The World Health Organization (WHO) recommends a daily intake of less than two grams per day—a target has not been achieved in any country. Currently, the American Heart Association recommends only 1.5 gram of sodium per day.
The PURE study is currently ongoing in 21 countries. The researchers—led by first author Andrew Mente, PhD, of the Population Health Research Institute, Hamilton Health Sciences and McMaster University in Ontario, Canada—analyzed work completed in 18 countries investigating the associations between the average community-level sodium and potassium intake, cardiovascular disease and death.
"Our study adds to growing evidence to suggest that, at 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,” Menthe said in a prepared statement. “This is the relationship we would expect for any essential nutrient and health. Our bodies need essential nutrients like sodium, but the question is how much.”
More than 95,700 individuals from 369 communities were assessed for blood pressure and more than 82,500 individuals were assessed for cardiovascular outcomes (for example, strokes). The researchers utilized morning fasting urine to estimate participants’ 24-hour sodium and potassium excretion to determine their intake and followed up after an average of eight years.
The researchers noted high sodium intake that was greater than five grams per day occurred in 80 percent of communities in China. In other countries, 84 percent of communities had an average intake of three to five grams per day.
They found that average systolic blood pressure readings increased by 2.86 mmHg for every gram of increased sodium intake, but positive association was only seen among communities with the highest sodium intake.
For every gram increase in sodium intake, the study subjects had an average additional 0.73 cardiovascular events per 1,000 years, though this relationship was non-linear. It was more dependent upon the population’s average daily consumption.
“The association between sodium intake and major cardiovascular events showed significant deviation from linearity, having a significant inverse association in the lowest tertile of sodium intake (4.04 grams per day and -1.00 CVD events per 1,000 years), no association in the middle tertile (4.7 grams per day and 0.24 CVD events per 1,000 years), and a non-significant positive association in the highest tertile (5.75 grams per day and 0.37 CVD events per 1,000 years),” Mente and colleagues wrote.
The association between sodium intake and stroke showed a positive association only among communities with an intake of more than 5.08 grams per day. There was no significant association found in the middle or lowest tertiles. A positive association was seen between sodium intake and stroke among the communities in China but not in other countries.
There were inverse associations between low sodium intake and increased rates of myocardial infarction (MI) and death. All major cardiovascular outcomes decreased with an increase in potassium consumption.
“Rather than a population-wide approach, our data suggest that a targeted approach of intervening in communities and countries with high mean sodium intakes (more than five grams per day) might improve reduction of cardiovascular disease (and strokes),” Mente et al. wrote. “Such an approach would avoid diversion of resources to communities with lower sodium intakes, where no correlation with increased rates of clinical events are seen, and those in which associations with blood pressure are small.”
As a senior news writer for TriMed, Subrata covers cardiology, clinical innovation and healthcare business. She has a master’s degree in communication management and 12 years of experience in journalism and public relations.