Experts have warned of a hidden factor that may be behind high blood pressure in millions of people around the world, beyond the traditional lifestyle-related causes.
People often associate high blood pressure with factors such as excessive salt intake, lack of physical activity, and smoking. However, public health researchers point to a less obvious source of sodium: the salinity of drinking water, especially in coastal areas.
As sea levels rise due to climate change, saltwater is gradually seeping into freshwater sources, leading to an increased concentration of salts—especially sodium—in the water that the population relies on for drinking and cooking.
A scientific review and meta-analysis of 27 studies and more than 74,000 participants from multiple countries revealed that people who consume more salty water have higher blood pressure levels than others. Their risk of developing hypertension also increases by up to 26%.
The results also showed an average increase in systolic blood pressure of approximately 3.22 mmHg and in diastolic blood pressure of approximately 2.82 mmHg among those most exposed to water salinity. While these differences may seem small at the individual level, their impact is amplified when considering large population groups.
This problem is most evident in coastal areas, where the intrusion of seawater into groundwater increases its salinity, given that millions of people—especially in low- and middle-income countries—rely on these sources as their primary source of drinking water.
Researchers warn that sodium consumption is not limited to food; individuals may unknowingly consume additional amounts through water, even if they do not notice the salty taste.
Although global efforts to prevent high blood pressure focus primarily on lifestyle modifications, these findings highlight the importance of environmental factors, which still receive less attention.
The researchers point out that the effect of water salinity may be similar to other known risk factors, such as lack of physical activity, which increase the likelihood of developing high blood pressure by between 15% and 25%.
Conversely, research remains limited on the relationship between drinking water salinity and serious heart conditions, such as heart attacks and strokes, which calls for further studies to determine safe salinity levels and their long-term effects.
It is noteworthy that the World Health Organization has not yet set a specific standard for sodium levels in drinking water, which reflects the need to strengthen scientific evidence in this area.
While food remains the main source of sodium, experts advise monitoring the quality of drinking water — where data is available — and paying attention to total sodium intake, especially in areas prone to high water salinity.
The report was prepared by Rajiv Chaudhary, Professor of Global Health – Florida International University.
