Although essential for health, the sodium contained in table salt and certain foods can be harmful in excess. In particular, it increases the risk of stroke and premature death.
Now, a new study reveals that removing just a tiny amount of salt from the daily diet can lower blood pressure, with “a decline comparable to the effect achieved with drugs”.
Adults should consume no more than 5g of salt per day (equivalent to 2g of sodium), or one teaspoon, according to the World Health Organization, but the health authority estimates that the global average is 10.8g.
“Eating too much salt makes it the top risk factor for diet- and nutrition-related deaths. More evidence is emerging documenting links between high sodium intake and increased risk of health conditions such as gastric cancer, obesity, osteoporosis and kidney disease,” the WHO warns.
It adds that the implementation of sodium-reduction policies in all regions of the world “could save an estimated 7 million lives globally by 2030”.
Researchers from Northwestern Medicine, Vanderbilt University Medical Center, and the University of Alabama at Birmingham examined this issue, basing their study on the daily sodium intake recommended by the American Heart Association, which advises not exceeding 2.3g per day or an ideal limit of 1.5g.
The scientists sought to assess the effect of reduced sodium on blood pressure, including in people being treated for hypertension. To that end, the study followed 213 individuals aged between 50 and 75 from two US cities – Birmingham and Chicago – who were randomly divided into two groups.
The first was asked to adopt a high-sodium diet (2.2g per day in addition to their usual diet), and the second a low-sodium diet (0.5g in total per day) for one week. Each group was then swapped onto the other diet for a week.
Published in the Journal of the American Medical Association, the study reports that systolic blood pressure fell by an average of 7-8mm of mercury on the low-sodium diet compared with the second diet, and by 6mm of mercury compared with the participants’ usual diet.
This concerned no less than 72% of the people included in the study.
“Middle-aged to elderly participants reduced their salt intake by about a teaspoon a day compared with their usual diet. The result was a decline in systolic blood pressure comparable to the effect produced by a commonly used first-line medication for high blood pressure,” said co-lead author Dr Deepak Gupta.
While his comments should be taken in the context of the study, they nevertheless highlight the impact that lowering salt, and therefore sodium, consumption can have day to day.
“The fact that blood pressure dropped so significantly in just one week and was well tolerated is important and emphasises the public health impact of dietary sodium reduction, given that high blood pressure is such a huge health issue worldwide,” co-author Dr Cora Lewis concluded.