Low sodium salt prevents stroke – sciencedaily

Both high sodium intake and low potassium intake are associated with high blood pressure and an increased risk of cardiovascular disease and premature death.^3.4 Salt substitutes, which replace some of the sodium chloride in common salt with potassium chloride, have been shown to lower blood pressure⁵ but their effects on heart disease, stroke, and death were uncertain. In addition, there were concerns about causing hyperkalemia in people with chronic kidney disease resulting in cardiac arrhythmias and sudden death.

The Salt Substitute and Stroke Study (SSaSS) compared the effect of a reduced sodium salt substitute versus common salt on stroke, cardiovascular events, mortality, and clinical hyperkalaemia.⁶ SSaSS was an open-label, cluster-randomized trial that recruited participants between April 2014 and January 2015. Participants were adults with previous stroke or aged 60 and over with poorly controlled blood pressure.⁷

The trial was carried out in 600 villages in rural areas of five Chinese provinces. Two counties within each province were chosen which represented the level of socio-economic development of rural counties in that province. About 35 people were recruited from each village, for a total of 20,995 participants. Participants were randomized into clusters per village in a 1: 1 ratio to the provision of salt substitute or continued use of common salt.

Participants in the intervention villages received a free salt substitute (approximately 75% sodium chloride and 25% potassium chloride) as a replacement for common salt and were advised to use it for all cooking. seasoning and preservation of food. They were also encouraged to use the replacement salt more sparingly than before to maximize their sodium reduction. A sufficient amount of salt substitute was provided to cover the needs of the entire household (approximately 20 g per person per day). The participants from the control villages continued their usual habits.

The average age of the participants was 65.4 years and 49.5% were female. Some 72.6% had a history of stroke and 88.4% had a history of hypertension.

During an average follow-up of 4.74 years, more than 3,000 people have had a stroke, more than 4,000 have died and more than 5,000 have had a major cardiovascular event. The risk of stroke was reduced with salt substitute compared to common salt (29.14 versus 33.65 per 1,000 patient-years; rate ratio [RR] 0.86; 95% confidence interval [CI] 0.77-0.96; p = 0.006).

Regarding secondary outcomes, major cardiovascular events (non-fatal stroke, non-fatal acute coronary syndrome, vascular death) were reduced with the salt substitute (49.09 vs. 56.29 per 1,000 patients -years; RR 0.87; 95% CI 0.80-0.94; p <0.001) as well as total mortality (39.27 versus 44.61 per 1,000 patient-years; RR 0.88; CI 95% 0.82-0.95; p <0.001).

Regarding safety, there was no increased risk of serious adverse events attributed to clinical hyperkalaemia with a salt substitute compared to common salt (3.35 vs. 3.30 per 1000 patients- years; RR 1.04; 95% CI 0.80-1.37; p = 0.76). No other risk has been identified either.

Principal investigator Professor Bruce Neal of the George Institute for Global Health, Sydney, Australia said: “This study provides clear evidence of an intervention that could be undertaken very quickly at very low cost. A recent modeling study done for China predicted that 365,000 strokes and 461,000 premature deaths could be prevented each year in China if the salt substitute was found to be effective.⁸ We have now shown that it is effective, and that is just a benefit for China. Salt substitution could be used by billions of others with even greater benefits. “

He added, “The result of the trial is particularly interesting because salt substitution is one of the few practical ways to achieve changes in salt intake. Other salt reduction interventions have struggled to achieve significant and lasting impact.

Importantly, the salt substitute is very easy to make and it is not expensive. A kilogram of regular salt, which lasts for months, costs around US $ 1.08 in China. The price per kilogram of salt substitute is $ 1.62 / kg, ” he said. “It is mainly low-income and more disadvantaged populations who add large amounts of salt when preparing and cooking food.⁹ This means that the salt substitute has the potential to reduce health inequalities linked to cardiovascular disease. “

Remarks

¹SSaSS: Salt substitutes and stroke study on the effect of salt substitutes on cardiovascular events and mortality

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

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

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

⁵Greer RC, Marklund M, Anderson CAM, et al. Salt substitutes fortified with potassium as a means of lowering blood pressure. Hypertension. 2020; 75: 266-274.

⁶Neal B, Tian M, Li N, et al. Rationale, Design, and Basic Features of the Salt Substitute and Stroke Study (SSaSS) – A Large-Scale Cluster Randomized Controlled Trial. Am heart J. 2017; 188: 109-117.

⁷Poorly controlled blood pressure was defined as: systolic blood pressure ≥ 140 mmHg if taking hypotensive drugs or systolic blood pressure ≥160 mmHg if she was not taking hypotensive drugs.

⁸Marklund M, Singh G, Greer R, et al. Estimating the population-level benefits and risks in China of sodium reduction through potassium-enriched salt substitution: a modeling study. BMJ. 2020; 369: m824.

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