Restricting sodium content in processed foods reduced blood pressure (BP) in one study and using a salt substitute reduced risks of stroke recurrence and death in another study, both published Feb. 5 in JAMA Cardiology, confirming the need to reduce sodium content in foods.

In one study, Thomas Gaziano, MD, FACC, et al., looked at how 24-hour urine sodium (24HrNa) excretion changed after mandatory sodium regulations were introduced in 2013. Regulations limited sodium by 25-80% in 13 categories of processed foods. The HAALSI (Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa) population-based study cohort included 5,059 adults aged ≥40 years living in rural South Africa (mean age, 62.4 years; 53.6% female). Spot urine samples were collected across three waves of data from 2014 to 2022.

Results demonstrated an overall reduction in mean 24HrNa excretion of 0.22 grams between the first two waves and a mean reduction of 0.23 grams between the first and third waves. Every gram of sodium reduction was associated with a −1.30 mm Hg reduction in systolic BP. The number of adults who achieved ideal sodium consumption (<2 g per day) increased from 7% to 17%. Thus, the significant reduction in 24HrNa excretion in this population was associated with reductions in BP, following implementation of sodium regulations.

In the other study, Xiong Ding, MPH, et al., examined how use of a reduced-sodium, added-potassium salt substitute vs. regular salt affected the incidence of recurrent stroke and all-cause mortality in a secondary analysis of the SSaSS (Salt Substitute and Stroke Study). SSaSS was conducted in 600 northern Chinese villages and showed that use of salt substitutes significantly decreased risks of stroke, total cardiovascular events and premature death. The current analysis included 15,249 patients with a hospital diagnosis of stroke after a baseline history of stroke (mean age, 64.1 years; 45.9% female).

Results showed that over a median follow-up of 61.2 months, the mean between-group difference in systolic BP was –2.05 mm Hg, and that 2,735 recurrent stroke events (691 fatal and 2,044 nonfatal) and 3,242 deaths occurred. Recurrent stroke was significantly lower in the salt substitute vs. regular salt group (rate ratio [RR], 0.86; 95% CI, 0.77-0.95), with a more marked effect on hemorrhagic stroke (relative reduction, 30%). Mortality rates were also significantly lower (RR, 0.88; 95% CI, 0.82-0.96), especially for stroke-related deaths (relative reduction, 21%). Therefore, using a potassium-based salt substitute led to reductions in recurrent stroke and all-cause mortality in patients with a history of stroke.

In an accompanying editorial comment, Daniel W. Jones, MD, et al., note that both studies demonstrated the benefit and safety of a low-sodium diet including salt substitutes. They suggest that these studies could be "the tipping point ... to move toward mandatory policies regarding sodium content of food."

Citations:

Gaziano T, Kapaon D, Du Toit JD, et al. Sodium reduction legislation and urinary sodium and blood pressure in South Africa. JAMA Cardiology. Published online February 5, 2025. doi:10.1001/jamacardio.2024.5410

Ding X, Zhang X, Huang L, et al. Salt substitution and recurrent stroke and death. JAMA Cardiology. Published online February 5, 2025. doi:10.1001/jamacardio.2024.5417