Salt in drinking water may affect heart health: study

(Web Desk) - Salt often appears in health advice about food. Chips, packaged meals, and fast food get most of the blame. Drinking water rarely enters public discussion.

Many people assume water stays neutral and harmless. New scientific evidence challenges that idea and shows salt in drinking water can affect heart health.

A large global study now links salty drinking water with higher blood pressure and a greater risk of hypertension. Coastal regions face stronger effects because underground freshwater sources often mix with seawater.

Climate change and rising sea levels increase that mixing, raising salt levels in water used for daily drinking.

A team of scientists reviewed existing evidence from around the world. Rajiv Chowdhury led the work as chair of the Department of Global Health at Florida International University.

The analysis combined the results of 27 population-based studies involving more than 74,000 participants.

Data came from the United States, Bangladesh, Vietnam, Kenya, Australia, Israel, and several European countries.

Many studies focused on coastal communities where salty groundwater often supplies drinking water.

Blood pressure shows how strongly blood pushes against artery walls. Doctors measure pressure using an inflatable cuff placed around the upper arm. The readings appear as two numbers, such as 120 over 80 millimeters of mercury.

The top number rises when the heart pumps blood. The bottom number reflects pressure during rest between beats. Higher values increase risk for heart disease, stroke, and kidney damage.

Salt plays a key role in controlling blood volume and vessel tension. Extra sodium causes water retention inside the body. More retained fluid raises blood volume, which increases pressure inside blood vessels.

The analysis found that people drinking more saline water showed higher average blood pressure. Systolic pressure increased by about 3.2 mm Hg. Diastolic pressure rose by nearly 2.8 mm Hg.

A 26 percent higher risk of hypertension also appeared among groups exposed to saltier water. Coastal populations showed stronger and more consistent effects.

“These are modest increases at the individual level,” Chowdhury said. “But when large populations are exposed, even small shifts in blood pressure can have significant public health effects.”

“To put it in perspective, the risk level observed in this study for water salinity is like other established cardiovascular risk factors, such as low physical activity, which increases hypertension risk by approximately 15 to 25%.”

Several biological processes help explain the findings. Higher sodium intake changes small arteries and increases resistance to blood flow.