Low-Sodium Salt Substitutes: A Nutritional Tool For Cardiovascular Health?

Reducing dietary salt/sodium intake by 30% worldwide at the population level is a WHO target for 2025. As part of the strategies to achieve this, experts who analyzed the effectiveness of low-sodium substitutes have recommended that industry and public health agencies work together to make these products affordable and widely available.

The World Health Organization (WHO) has set a target that is a global challenge: to achieve a 30% reduction in salt (sodium) intake by 2025. This not only involves modifying the taste of foods, but minimizing one of the most important risk factors for non-communicable diseases (NCDs): hypertension.

A systematic review conducted by the Cochrane Database, Low sodium Salt substitutes: a tool for sodium reduction and cardiovascular health, analyzed scientific papers on the subject and observed that reducing dietary salt/sodium intake at the population level is considered a cost-effective or profitable intervention, with the potential to make a significant impact on reducing the burden of NCDs, particularly premature mortality from ischemic heart disease and stroke.

Low sodium salt substitutes (LSSS) vary in their formulation, but what they all have in common is lower sodium content than traditional table salt. The key is to replace a portion of the sodium with alternative products, mainly potassium chloride.

To that end, as the arm of the WHO in the region, the Pan American Health Organization (PAHO) has put in place a regional line of action — prevention of cardiovascular disease through dietary salt reduction — aimed at implementing cost-effective interventions and policies at the population level to reduce salt/sodium intake and improve population health.

There is robust evidence of the link between sodium intake and high blood pressure, one of the most important risk factors for cardiovascular disease (CVD). There is also evidence of an association between high sodium intake and CVD outcomes, including acute coronary syndrome and stroke.

It is estimated that high salt intake was responsible for 1.9 million deaths and 45 million disability-adjusted life years in 2019. The WHO recommends that adults consume no more than 5 g of salt per day (equivalent to 2 g of sodium per day), yet average consumption is still 10 g per day (3.95 g of sodium per day). Potassium intake, on contrast, is lower than recommended.

A Cochrane systematic review and meta-analysis by a group of British researchers examined the scientific evidence from 26 randomized controlled trials (a total of 34,961 participants) on the impact on cardiovascular health of LSSS use in adults and children. It also looked at certain adverse effects, such as abnormal heart rhythms resulting from high blood potassium levels.

The trials analyzed lasted between two months and five years; most replaced standard salt with LSSS, and four of the trials added LSSS directly to products, foods, and condiments.  Fourteen of the 26 investigations were conducted in low- and middle-income countries.

The meta-analyses demonstrated an average reduction in systolic blood pressure of 4.76 mmHg (95% confidence interval [CI]: 3.50 to 6.01 lower) and a reduction in diastolic blood pressure of 2.43 mmHg (95% CI: 3.50 to 1.36 lower) with the use of LSSS.

They also revealed small decreases in non-fatal stroke, non-fatal acute coronary syndrome, and cardiovascular mortality in adults. Although all of the trials excluded people who were at high risk of hyperkalemia (those with impaired renal function, diabetes, or taking potassium-sparing medications), seven trials included people who were possibly at risk of hyperkalemia, providing valuable evidence regarding the adverse effects of LSSS. 

The findings of the analysis highlighted by the researchers include:

• The review provides valuable evidence for lawmakers and policymakers, with the goal of reducing sodium intake.
• The figures on reduction of blood pressure by replacing regular salt intake with LSSS was compatible with the reductions observed with the use of several classes of antihypertensive drugs.
• This is also likely to be associated with substantial population-level benefits, resulting in improved cardiovascular health at the local or regional level.
• The substitution strategy to reduce salt intake could be particularly effective in reducing CVD in low-income countries, where salt consumption is high.
• In other settings, where the proportion of discretionary salt is much lower, mandatory reformulation of processed foods to lower their sodium content will remain the most effective strategy for salt reduction.
• The discussion should remain open, and more research is needed on the risk of hyperkalemia associated with LSSS, particularly among the high-risk patients who were excluded from the studies in this meta-analysis. 
• Obstacles to widespread implementation of LSSS remain, including potential changes in taste, the higher price of LSSS compared to common salt, and lack of widespread availability.
• Care must also be taken to maintain healthy iodine levels in the population, and under these circumstances the use of iodized LSSS may be considered.
• Implementation of the comprehensive salt reduction strategies recommended by the WHO is urgently needed, and current evidence points to LSSS as a useful tool in many settings.

This story was produced using content from the original study and from other medical research, as well as health and public health sources, highlighted in related links throughout the article.