A new international study has found that sodium levels long considered “normal” may still increase the risk of high blood pressure and heart failure, especially in older adults.
Researchers analyzed health records from over 400,000 adults and found that even sodium levels considered “normal” by current medical standards may significantly increase the risk of two of the most common chronic conditions in older Americans: high blood pressure and heart failure.
The study, published in the European Journal of Preventive Cardiology, tracked participants for up to 20 years. It found that individuals with serum sodium levels between 140 and 142 mmol/L faced a 13% higher risk of developing hypertension. Those with levels above 143 mmol/L saw that risk jump to 29%—and a 20% increase in heart failure risk as well.
To put that in context, a “normal” sodium range is defined as 135–146 mmol/L. But these new findings suggest the upper half of that range may not be as safe as previously thought.
This isn’t just about salt in the diet. The research highlights hydration as a key factor. According to the scientists, many people may be living in a state of chronic, mild dehydration, which pushes sodium levels higher. When that happens, the body triggers biological responses—like the release of antidiuretic hormone and activation of the sympathetic nervous system—that can raise blood pressure over time.
“This study adds compelling evidence that staying well-hydrated may help reduce the long-term risk of serious conditions like hypertension and heart failure,” said Professor Jonathan Rabinowitz of Bar-Ilan University, one of the lead researchers. He collaborated with scientists from Israel’s Leumit Healthcare Services and the U.S. National Institutes of Health.
Importantly, the study only included healthy adults with no pre-existing heart or kidney conditions, diabetes, or other chronic diseases. That means these findings apply even to those who otherwise consider themselves in good health.
More than half of those studied had sodium levels above 140 mmol/L. Specifically, 39% were in the 140–142 mmol/L bracket, and another 19% were in the 143–146 mmol/L range—meaning nearly 60% of participants fell into categories now linked to heightened risk.
The authors suggest a simple solution: drink more water. While dietary salt adjustments have only a modest impact on serum sodium, drinking an extra liter of water can reduce sodium levels by about 3 mmol/L. That could be enough to move someone out of the risk zone.
“Hydration is often overlooked in chronic disease prevention,” Rabinowitz noted. “A simple blood test might flag people who could benefit from basic lifestyle adjustments.”
Heart disease and high blood pressure are two of the most common chronic conditions affecting older adults in the U.S. This study offers a timely warning: even “normal” sodium levels might quietly contribute to those risks.
Doctors may soon begin advising patients to not only check whether their sodium levels fall within range, but where exactly in that range they are. For many, a glass of water might be a small step toward avoiding serious heart trouble down the road.