Low-Sodium Salt Cuts Stroke Risk

Lowering Stroke Risk with Salt Substitute

Replacing common salt with a salt substitute significantly lowers stroke risk today. This is especially true for people who already have high blood pressure. Patients who have suffered a past stroke also gain immense benefit immediately. Late-breaking data from a major study confirms this finding clearly. This information was presented at the ESC Congress 2021 recently. The findings were also published in the New England Journal of Medicine successfully.

The Problem with Sodium and Potassium

High blood pressure causes a major increase in health risks constantly. This pressure strongly links to cardiovascular disease and early death frequently. High salt intake contributes directly to elevated blood pressure significantly. Furthermore, inadequate potassium intake worsens the situation considerably. Both factors work against heart health continuously. Salt substitutes address this dual problem effectively and immediately.

Ordinary salt contains sodium chloride primarily. Salt substitutes swap some of this sodium chloride for potassium chloride instead. Earlier research proved these substitutes could lower blood pressure successfully. However, we did not know their overall impact on heart disease and stroke. Concerns existed that the added potassium could cause a problem. This worry focused on hyperkalemia, a condition of high blood potassium. Hyperkalemia can cause serious heart rhythm problems and sudden death sometimes. This risk was particularly noted for people with chronic kidney disease actively.

The Salt Substitute and Stroke Study (SSaSS)

The Salt Substitute and Stroke Study (SSaSS) addressed these crucial unknowns directly. Researchers examined the effects of the low-sodium salt substitute carefully. They compared it against using conventional salt on several outcomes. These outcomes included stroke occurrence, cardiovascular events, and overall mortality. Furthermore, researchers specifically monitored clinical hyperkalemia for safety.

The open, cluster-randomized trial recruited participants between 2014 and 2015 actively. Researchers included adults with a definite history of stroke clearly. They also included people aged 60 or older with poorly controlled blood pressure.

Poorly controlled blood pressure meant systolic pressure was  140 mmHg or more while taking medication. It meant systolic pressure was  160 mmHg or more when not taking medication.

The trial took place across 600 villages throughout five different Chinese regions. Researchers selected two counties within each province strategically. This selection aimed to represent the socioeconomic development of rural counties effectively. A large total of 20,995 people joined the study ultimately. Each village contributed about 35 participants to the trial. Researchers randomized participants by village into two groups equally. One group received the salt substitute immediately. The control group continued consuming their conventional salt as usual.

The Intervention and Control Groups

Participants in the intervention villages received a free salt substitute immediately. This product contained about 75 percent sodium chloride primarily. The remaining 25 percent consisted of potassium chloride instead. Participants used this substitute for all cooking, seasoning, and food preservation effectively. Researchers also advised them to use the salt substitute more sparingly than before. This instruction aimed to maximize the overall sodium reduction quickly. The supply ensured enough salt replacement for the entire household. They provided about  20g per person per day consistently. Participants in the control villages simply continued their daily routines as normal.

The average participant age was  65.4  years old across the study. Nearly  50 percent 49.5%  of the participants were female overall. A large majority 72.6% had previously suffered a stroke already. An even greater number (88.4%) had previous hypertension successfully.

Key Study Findings

The average follow-up period lasted for 4.74 years approximately. During this time, over 3,000 persons experienced a stroke unfortunately. Over 4,000 individuals died during the study duration. More than 5,000 participants suffered a major cardiovascular event overall.

The salt substitute significantly lowered the risk of stroke compared to ordinary salt. The rate decreased from  33.65 to 29.14  per 1,000 patient-years. This represented a substantial  14%  reduction in risk (rate ratio  0.86$; $p=0.006).

Secondary Outcomes:

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  Total Mortality: Total death risk also dropped with the salt substitute actively. The rate decreased from 44.61 to 39.27 per 1,000 patient-years. This represented a 12%reduction (rate ratio 0.88; p<0.001).

  
  


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  Major Cardiovascular Events: Events like non-fatal stroke and vascular death decreased significantly. Non-fatal acute coronary syndrome was also included in this group. The risk dropped from 56.29 to 49.09 per 1,000 patient-years. This meant a 13% risk reduction overall (rate ratio 0.87; p<0.001).

  
  

Safety and Conclusion

The study found no significant safety difference between the groups. Major adverse events from clinical hyperkalemia showed no variation. The rates were 3.35 versus 3.30 per 1,000 patient years (rate ratio 1.04; p=0.76). No further risks were discovered during the trial.

Professor Bruce Neal, the principal investigator, shared his enthusiasm. “This study gives unambiguous evidence for an effective intervention,” he stated clearly. He further emphasized the low cost and ease of immediate uptake actively. Modeling research for China estimated huge yearly benefits. The country could avert 365,000 strokes and 461,000 premature deaths annually. “We’ve now demonstrated that it works,” Professor Neal concluded confidently. He believes hundreds of millions of people could benefit globally.

Most importantly, salt replacement remains both simple and inexpensive to implement. Conventional salt in China costs around US$1.08 per kilogram usually. A kilogram of the salt replacement costs only 1.62 US dollars typically. Lower-income populations often use more salt in cooking and preparation generally. This low cost means salt substitutes can alleviate cardiovascular disease disparities effectively. They provide a powerful, affordable tool for global health improvement today.

References and notes

1. SSaSS: Salt Substitute and Stroke Study into the effect of salt substitutes on cardiovascular events and death


2. Tian M, et al. The effect of salt substitute on cardiovascular events and death (SSaSS). N Engl J Med. 10.1056/NEJMoa2105675


3. Cogswell ME, Mugavero K, Bowman BA, Frieden TR. Dietary sodium and cardiovascular disease risk–measurement matters. N Engl J Med. 2016;375:580–586.


4. Aburto NJ, Hanson S, Gutierrez H, et al. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ. 2013;346:f1378.


5. Greer RC, Marklund M, Anderson CAM, et al. Potassium-enriched salt substitutes as a means to lower blood pressure. Hypertension. 2020;75:266–274.


6. Neal B, Tian M, Li N, et al. Rationale, design, and baseline characteristics of the Salt Substitute and Stroke Study (SSaSS)-A large-scale cluster randomized controlled trial. Am Heart J. 2017;188:109–117.


7. Researchers defined poorly controlled blood pressure as: systolic blood pressure equaled 140 mmHg or more if the patient took blood pressure lowering medication, or systolic blood pressure equaled 160 mmHg or more if the patient did not take blood pressure lowering medication.


8. Marklund M, Singh G, Greer R, et al. Estimated population wide benefits and risks in China of lowering sodium through potassium enriched salt substitution: modelling study. BMJ. 2020;369:m824.


9. Bhat S, Marklund M, Henry ME, et al. A systematic review of the sources of dietary salt around the world. Adv Nutr. 2020;11:677–686.

The National Health and Medical Research Council supported the study (APP1164206 and APP1049417). Researchers purchased the study salt substitute from local manufacturers in each province for years 1, 2, and 5, but Jiangsu Sinokone Technology Company Limited provided it free of charge for years 3 to 4.

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