The daily sodium intake guidelines offered by the US Centers for Disease Control and Prevention are "excessively and unrealistically low," according to a new study from researchers at the University of Copenhagen Hospital in Denmark and published in the American Journal of Hypertension.
Currently, the Centers for Disease Control and Prevention (CDC) suggest a sodium intake of less than 2,300 mg per day for people under 50 years old, and less than 1,500 mg per day for people over 50 years old.
Doubt was first cast on the CDC recommendations in a 2013 report from the Institute of Medicine (IOM) - of which lead author of the new study, Dr. Niels Graudal, is a member. That report, however, was unable to offer its own recommendations for sodium intake.
The new analysis combines the results of 25 individual studies on health risks associated with sodium intake, assessing 274,683 people in total.
"Our results are in line with the IOM's concern that lower levels could produce harm," says Dr. Graudal, "and they provide a concrete basis for revising the recommended range in the best interest of public health."
"The good news," he continues, "is that around 95% of the global population already consumes within the range we've found to generate the least instances of mortality and cardiovascular disease."
Average American's sodium intake is 'more healthy' than CDC recommendations
The analysis did not find that a low-sodium intake is associated with beneficial effects on cardiovascular disease or improved mortality.
The "vast majority" of Americans consume between 2,645 mg and 4,945 mg of sodium each day. Dr. Graudal and colleagues find that, despite that intake being much higher than the CDC recommendations, it is actually healthier than the intake range suggested by the CDC.
The study recorded "a U-shaped correlation between sodium intake and health outcomes." The researchers found that when consumption of sodium fell outside the range of 2,645-4,945 mg per day, there was an increase in mortality. This means that both excessively high and excessively low intakes of sodium were linked to an increased risk of death.
In their conclusion, Dr. Graudal and colleagues assert that in none of the studies covered by the analysis was a low-sodium intake associated with beneficial effects on cardiovascular disease or improved mortality.
Why are the CDC guidelines and the findings of this study so at odds?
Medical News Today asked Dr. Graudal for his opinion on why the CDC's sodium intake recommendations are at odds with his findings.
"If you ask the CDC, they would tell you that there is massive evidence for sodium reduction in blood pressure trials showing very significant effects of sodium reduction on blood pressure and that this blood pressure reduction 'inevitably' would lead to a reduction in mortality," he responded.
"Then they would mention a few of these blood pressure studies, for instance DASH [Dietary Approaches to Hypertension] and TOHP [Trials of Hypertension Prevention], which to some degree support their claims, but they would 'forget' to mention the many blood pressure studies, which do not support their position.
They would not be able to support the claim that a blood pressure reduction by sodium reduction would lead to a decreased mortality, because such studies do not exist."
"They would also tell you that the results of the population studies included in our meta-analyses could be explained by confounders," Dr. Graudal continued, "and if you tell them that almost all of these studies were corrected for confounders, they would tell you that the results were due to residual confounding."
Dr. Graudal admitted that argument can never be excluded, but insisted that the CDC have no data to support this view. "In spite of this," he added, "I do not think that the CDC would consider the possibility that the CDC might be wrong."
Medical News Today also asked Dr. Graudal whether he considered there to be any resistance from the CDC in adopting his research.
"I think that sodium reduction has become an ideology for the CDC," he explained. "As long as the present key persons in the CDC take the decisions, there is no chance that they would accept the results of our analysis. They will explain the results away. A change in the position of the CDC would demand a change of the personnel."