A team of researchers from Bar-Ilan University examined 20 years of electronic health records from more than 407,000 healthy adults enrolled in Leumit Healthcare Services, one of Israel’s largest health providers. Their findings, published in the peer-reviewed European Journal of Preventive Cardiology, suggest that individuals with sodium levels at the higher end of the normal range face significantly elevated risks for high blood pressure and heart failure.

Till now, the 135–146 mmol/L sodium range was broadly accepted as “normal,” with little clinical concern unless levels were outside this band. But the Bar-Ilan study found that otherwise healthy individuals with sodium levels between 140–146 mmol/L still face measurably higher risks of developing chronic cardiovascular conditions.

For those with levels above 143 mmol/L, the risk jumped to 29% for hypertension and 20% for heart failure.

“Our findings point to hydration as a critical and overlooked part of chronic disease prevention,” said Prof. Jonathan Rabinowitz of the Weisfeld School of Social Work at Bar-Ilan University, who led the study. “A simple blood test might flag people who could benefit from basic lifestyle adjustments—like drinking more water, which reduces sodium levels.”

The researchers tied in hydration by using blood sodium levels as an indirect marker of a person’s hydration status. Sodium concentration in the blood rises when the body is underhydrated because there’s not enough water to dilute the sodium.

Nearly 60% of participants had sodium levels falling within the risk-associated range, underscoring how widespread the issue may be even among healthy populations. The associations held firm even after accounting for variables such as age, sex, body mass index, smoking, potassium levels, and blood pressure. To ensure the data accurately reflected hydration-related risks, individuals with conditions affecting water balance were excluded from the analysis.

“Hydration is often overlooked in chronic disease prevention,” Rabinowitz added. “This study adds compelling evidence that staying well-hydrated may help reduce the long-term risk of serious conditions like hypertension and heart failure.”

The US National Academies of Sciences, Engineering, and Medicine recommends a daily fluid intake of approximately 3.7 liters for adult men and 2.7 liters for adult women. However, individual hydration needs can vary based on factors such as age, activity level, climate, and health status.

PHOTO: Use according to Section 27 A