Can drinking-water minerals help lower hypertension?

Although drinking saline water is often associated with higher blood pressure due to additional salt intake, new research suggests that several beneficial minerals in mild-saline water may help lower blood pressure.

People in coastal Bangladesh are more prone to consuming saline water due to seawater intrusion to groundwater. Photo: GMB Akash / icddr,b

The mineral sodium (Na+), one of the dissolved elements in saline water, is a major contributor to high blood pressure or hypertension. However minerals such as calcium (Ca2+), and magnesium (Mg2+), if adequately concentrated in saline water, may help lower blood pressure - indicates a new study with icddr,b published in Journal of the American Heart Association.

“We have found that drinking mildly (not highly) saline water, containing good concentration of Ca2+ and Mg2+, is associated with lower blood pressure,” says Dr Mahbubur Rahman, an author of the study and project coordinator at icddr,b.

The research analysed around 6500 blood pressure measurements from coastal Bangladesh individuals, who were also assessed for their 24-hour urinary excretion of minerals like Na+, Ca2+,and Mg2+.

Compared to the freshwater drinkers, drinkers of mildly saline water with good concentrations of Ca2+ and Mg2+ had lower blood pressure, found the study.

“Our finding does not invalidate the fact that higher Na+ intake through saline water increases the risk of hypertension,” explains Dr. Abu Mohd Naser, principal author of the study and former icddr,b scientist now working with Rollins School of Public Health at Emory University.

Additionally, rigorous analysis of saline water specimens from our study suggests that the blood pressure lowering effects of Ca2+ and Mg2+ overweigh the blood pressure promoting effects of Na+.

“What we learn from this research is that beneficial minerals Ca2+, and Mg2+ can be added to drinking water as a new approach for lowering blood pressure. However, the effectiveness of such approach needs to be validated by epidemiological studies,” suggests Dr Naser.

The concentrations of types of minerals dissolved in water dictates the human health effects. Photo: GMB Akash / icddr,b

People in coastal Bangladesh are more prone to consuming saline water due to seawater intrusion to their groundwater aquifer influencing their mineral intake through saline water, notes the research.

Water salinity indicates the total amount of dissolved minerals - therefore, the concentrations of types of minerals dissolved in water dictates the human health effects.

“Mildly saline water samples in our study have shown to contain good concentrations of salubrious Ca2+ and Mg2+ in addition to the harmful Na+,” says Dr Naser.

Nevertheless, consumption of very high-salinity water will be still harmful due to high concentrations of harmful Na+, he adds.

The research also acknowledges that high concentrations of sodium and other beneficial minerals such as magnesium and calcium are not consistent in coastal groundwater in different seasons and geographical areas. Therefore saline water, depending on the mineral composition, can be beneficial for some people while it may be harmful to others in a different coastal area.

The study was supported by Wellcome Trust, UK through Our Planet, Our Health Award grant.

Muhammad Nabil