Potential use of salt substitutes to reduce blood pressure

Salt substitute recommendations for heart failure patients may influence guideline-directed medical therapies titration

AIMS

Reducing sodium intake is necessary for patients with chronic heart failure (CHF). Salt substitutes (saltSubs) have become increasingly popular as recommendations by healthcare professionals (HCPs) as well as options for patients and their caregivers. However, their consumption is generally potassium based and remains poorly evaluated in CHF management. Their impact on guideline-directed medical therapies (GDMTs) also remains unknown. The primary objective of this study was to provide a description and estimate of HCP recommendations and reported use of saltSubs in France. Secondary objectives were to identify if there was an association between these recommendations by HCPs and the use of GDMTs.

METHODS AND RESULTS

A nationwide, questionnaire-based, cross-sectional, epidemiological study was conducted from September 2020 to July 2021. Data collection included baseline characteristics, the use and recommendations of saltSubs, and the use of GDMTs, which included (i) angiotensin-converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) or angiotensin receptor-neprilysin inhibitors (ARNis), (ii) mineralocorticoid receptor antagonists (MRAs), and/or (iii) beta-blockers (BBs). In total, 13% of HCPs advised saltSubs and 17% of patients and 22% of caregivers reported their consumption. CHF patients advised to take saltSubs did not differ in terms of left ventricular ejection fraction (EF) <40%, ischaemic origin, and New York Heart Association III-IV class, but were more recently hospitalized for acute HF (P = 0.004). HCPs who recommended saltSubs to patients were more likely to advise an anti-diabetic diet (P < 0.001), cholesterol-lowering diet (P < 0.001), and exercise (P = 0.018). In the overall population, ACEi/ARB/ARNi use was less frequent in case of saltSub recommendations (74% vs. 82%, P = 0.012). The concomitant prescription of none, one, two, or three GDMTs was less favourable in case of saltSub recommendations (P = 0.046). There was no significant difference for the presence of MRA (56% vs. 58%) and/or BB (78% vs. 82%). The under-prescription of ACEi/ARB/ARNi was found when patients had EF < 40% (P = 0.029) and/or EF ≥ 40% (P = 0.043). In the subgroup with left ventricular EF ≥ 40%, we found a higher thiazide use (P = 0.014) and a less frequent use of low EF GDMTs (P = 0.044) in case of being recommended saltSubs.

CONCLUSIONS

Beyond the well-established risk for hyperkalaemia, our preliminary results suggest a potentially negative impact of saltSubs on GDMT use, especially for ACEis/ARBs/ARNis in CHF management. saltSub recommendations and their availability from open sale outlets should be considered to avoid possible misuse or deference from GDMTs in the future. Informed advice to consumers should also be considered from HCPs or pharmacists.

Measuring Sodium from Discretionary Salt: Comparison of Methods

(1) Background: The best method to assess discretionary salt intake in population surveys has not been established. (2) Methods: This secondary analysis compared three different methods of measuring sodium intake from discretionary salt in a convenience sample of 109 adults in New Zealand. Participants replaced their household salt with lithium-tagged salt provided by researchers over eight days. Baseline 24 h urine was collected, and two further 24 h urine and 24 h dietary recalls were collected between days six and eight. Discretionary salt was estimated from the lithium-tagged salt, focused questions in the 24 h dietary recall, and the 'subtraction method' (a combination of 24 h urine and 24 h dietary recall measures). (3) Results: Around one-third of estimates from the 'subtraction method' were negative and therefore unrealistic. The mean difference between 24 h dietary recall and lithium-tagged salt estimates for sodium from discretionary salt mean were 457 mg sodium/day and 65 mg/day for mean and median, respectively. (4) Conclusions: It is possible to obtain a reasonable estimate of discretionary salt intake from careful questioning regarding salt used in cooking, in recipes, and at the table during a 24 h recall process to inform population salt reduction strategies.

Advancing Health Research Impact through a Systemic Multi-Sectoral Approach: A Protocol for Introducing Reduced-Sodium Salts and Salty Condiments in Vietnam

Better alignment between health research organisations with the needs (and interests) of key stakeholders in the health policy and research system is critical to improving research impact. The George Institute for Global Health's 'Healthier Societies' program focuses on harnessing the power of governments, markets, and communities to improve population level health equity outcomes and maximise research impact. This protocol outlines a systemic multi-sectoral approach to advance health research impact globally applied to a project to reduce population salt intake in Vietnam by introducing reduced-sodium salts and salty condiments. We defined a systemic multi-sectoral approach to be a strategy that involves engaging with government, market and communities in a deliberate and joined-up way to solve a problem in which they all have a role to play. The project objectives are to: (i) produce reduced-sodium fish sauce products and test consumer acceptability; (ii) investigate the market feasibility of introducing reduced-sodium foods (salt, bot canh and fish sauce) into the Vietnamese market; (iii) estimate the cost-effectiveness of three different government strategies to support the implementation of reduced-sodium products; and (iv) develop an advocacy roadmap to maximise potential research impact. Methods will include standard quality and safety assessments, consumer sensory testing for the locally produced reduced-sodium fish sauces, market feasibility assessment (including collating market data and semi-structured interviews with stakeholders), cost-effectiveness modelling (Markov cohort model), multi-sector stakeholder engagement, and the development of a coordinated advocacy strategy using the Kotter Plus framework. Health research organisations are increasingly seeking ways to achieve greater impact with their research. Through the application of a systemic multi-sectoral approach with governments, markets and communities, this protocol provides an example of how health research projects can achieve such impact.

Replacing salt with low-sodium salt substitutes (LSSS) for cardiovascular health in adults, children and pregnant women

BACKGROUND

Elevated blood pressure, or hypertension, is the leading cause of preventable deaths globally. Diets high in sodium (predominantly sodium chloride) and low in potassium contribute to elevated blood pressure. The WHO recommends decreasing mean population sodium intake through effective and safe strategies to reduce hypertension and its associated disease burden. Incorporating low-sodium salt substitutes (LSSS) into population strategies has increasingly been recognised as a possible sodium reduction strategy, particularly in populations where a substantial proportion of overall sodium intake comes from discretionary salt. The LSSS contain lower concentrations of sodium through its displacement with potassium predominantly, or other minerals. Potassium-containing LSSS can potentially simultaneously decrease sodium intake and increase potassium intake.  Benefits of LSSS include their potential blood pressure-lowering effect and relatively low cost. However, there are concerns about potential adverse effects of LSSS, such as hyperkalaemia, particularly in people at risk, for example, those with chronic kidney disease (CKD) or taking medications that impair potassium excretion.

OBJECTIVES

To assess the effects and safety of replacing salt with LSSS to reduce sodium intake on cardiovascular health in adults, pregnant women and children.

SEARCH METHODS

We searched MEDLINE (PubMed), Embase (Ovid), Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection (Clarivate Analytics), Cumulative Index to Nursing and Allied Health Literature (CINAHL, EBSCOhost), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to 18 August 2021, and screened reference lists of included trials and relevant systematic reviews. No language or publication restrictions were applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and prospective analytical cohort studies in participants of any age in the general population, from any setting in any country. This included participants with non-communicable diseases and those taking medications that impair potassium excretion. Studies had to compare any type and method of implementation of LSSS with the use of regular salt, or no active intervention, at an individual, household or community level, for any duration.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles, abstracts and full-text articles to determine eligibility; and extracted data, assessed risk of bias (RoB) using the Cochrane RoB tool, and assessed the certainty of the evidence using GRADE. We stratified analyses by adults, children (≤ 18 years) and pregnant women. Primary effectiveness outcomes were change in diastolic and systolic blood pressure (DBP and SBP), hypertension and blood pressure control; cardiovascular events and cardiovascular mortality were additionally assessed as primary effectiveness outcomes in adults. Primary safety outcomes were change in blood potassium, hyperkalaemia and hypokalaemia.

MAIN RESULTS

We included 26 RCTs, 16 randomising individual participants and 10 randomising clusters (families, households or villages). A total of 34,961 adult participants and 92 children were randomised to either LSSS or regular salt, with the smallest trial including 10 and the largest including 20,995 participants. No studies in pregnant women were identified. Studies included only participants with hypertension (11/26), normal blood pressure (1/26), pre-hypertension (1/26), or participants with and without hypertension (11/26). This was unknown in the remaining studies. The largest study included only participants with an elevated risk of stroke at baseline. Seven studies included adult participants possibly at risk of hyperkalaemia. All 26 trials specifically excluded participants in whom an increased potassium intake is known to be potentially harmful. The majority of trials were conducted in rural or suburban settings, with more than half (14/26) conducted in low- and middle-income countries. The proportion of sodium chloride replacement in the LSSS interventions varied from approximately 3% to 77%. The majority of trials (23/26) investigated LSSS where potassium-containing salts were used to substitute sodium. In most trials, LSSS implementation was discretionary (22/26). Trial duration ranged from two months to nearly five years.  We assessed the overall risk of bias as high in six trials and unclear in 12 trials. LSSS compared to regular salt in adults: LSSS compared to regular salt probably reduce DBP on average (mean difference (MD) -2.43 mmHg, 95% confidence interval (CI) -3.50 to -1.36; 20,830 participants, 19 RCTs, moderate-certainty evidence) and SBP (MD -4.76 mmHg, 95% CI -6.01 to -3.50; 21,414 participants, 20 RCTs, moderate-certainty evidence) slightly.  On average, LSSS probably reduce non-fatal stroke (absolute effect (AE) 20 fewer/100,000 person-years, 95% CI -40 to 2; 21,250 participants, 3 RCTs, moderate-certainty evidence), non-fatal acute coronary syndrome (AE 150 fewer/100,000 person-years, 95% CI -250 to -30; 20,995 participants, 1 RCT, moderate-certainty evidence) and cardiovascular mortality (AE 180 fewer/100,000 person-years, 95% CI -310 to 0; 23,200 participants, 3 RCTs, moderate-certainty evidence) slightly, and probably increase blood potassium slightly (MD 0.12 mmol/L, 95% CI 0.07 to 0.18; 784 participants, 6 RCTs, moderate-certainty evidence), compared to regular salt.  LSSS may result in little to no difference, on average, in hypertension (AE 17 fewer/1000, 95% CI -58 to 17; 2566 participants, 1 RCT, low-certainty evidence) and hyperkalaemia (AE 4 more/100,000, 95% CI -47 to 121; 22,849 participants, 5 RCTs, moderate-certainty evidence) compared to regular salt. The evidence is very uncertain about the effects of LSSS on blood pressure control, various cardiovascular events, stroke mortality, hypokalaemia, and other adverse events (very-low certainty evidence). LSSS compared to regular salt in children: The evidence is very uncertain about the effects of LSSS on DBP and SBP in children. We found no evidence about the effects of LSSS on hypertension, blood pressure control, blood potassium, hyperkalaemia and hypokalaemia in children.

AUTHORS' CONCLUSIONS

When compared to regular salt, LSSS probably reduce blood pressure, non-fatal cardiovascular events and cardiovascular mortality slightly in adults. However, LSSS also probably increase blood potassium slightly in adults. These small effects may be important when LSSS interventions are implemented at the population level. Evidence is limited for adults without elevated blood pressure, and there is a lack of evidence in pregnant women and people in whom an increased potassium intake is known to be potentially harmful, limiting conclusions on the safety of LSSS in the general population. We also cannot draw firm conclusions about effects of non-discretionary LSSS implementations. The evidence is very uncertain about the effects of LSSS on blood pressure in children.

Dietary Modelling to Explore the Impact of Potassium Chloride Replacement for Sodium in Bread for Adults with Chronic Kidney Disease

Food manufacturers are increasingly substituting potassium chloride (KCl) in food products so as to reduce the sodium chloride content. Bread and bread products are common staple foods in many Western households and are a target for recipe reformulation using KCl. Given that chronic kidney disease (CKD) is a medical condition of global importance that requires dietary potassium restriction in the later stages, we sought to evaluate the impact and safety of varying levels of KCl substitution in bread products. We undertook a secondary analysis of dietary data from the National Nutrition and Physical Activity Survey 2011–2012 for 12,152 participants (154 participants with CKD). The sodium chloride content in bread and bread-based products was substituted with 20%, 30%, and 40% of KCl. The contribution of these alterations in the dietary potassium intake to the total daily potassium intake were then examined. The replacement of sodium in bread with varying amounts of KCl (20%, 30%, and 40%) resulted in one third of people with CKD exceeding the safe limits for dietary potassium consumption (31.8%, 32.6%, and 33%, respectively). KCl substitution in staple foods such as bread and bread products have serious and potentially fatal consequences for people who need to restrict dietary potassium. Improved food labelling is required for consumers to avoid excessive consumption.

Reduction of Sodium Intake from Papaya Salad with the Use of Sodium-Reduced Fermented Fish in Producing Traditional Seasoning Sauce

Fermented fish is a common seasoning used in Northeastern Thailand and Laos to give food a salty taste. It is also used as a basic ingredient for preparing various seasoning sauces for many local dishes. This study examined the effect of sodium reduced fermented fish (SRFF) on reducing the sodium content in prepared traditional papaya salad. Three local producers provide fermented fresh water fish produced with either normal salt (FF) or 60% sodium-reduced salt (SRFF) that were then used by 3 local sauce producers to make papaya salad seasoning sauces. Three local street food vendors then were used these sauces as the main ingredients for preparing their papaya salads. Sodium contents of the FFs, SRFFs, and papaya salads were analyzed using Inductively Coupled Plasma-Optical Emission Spectrometer. Significant differences between sodium contents in sauces and papaya salads were evaluated using the t-test. Results showed that the SRFF contained 54% less sodium than the FF, while sodium in the SRFF sauces was approximately 42% less than from FF sauces. The papaya salads prepared from SRFF sauces contained on average 492±27 mg sodium per 100 g, which was 33% lower than those prepared from FF sauces. The use of SRFF could significantly reduce sodium content in traditional papaya salad by up to one-third, which could be beneficial in lowering the risk of hypertension among Norteastern Thai and Laotain people with minimal change in eating behaviors.

The Macronutrient Content of Sodium-Modified Foods Is Unchanged Compared with Regular Counterparts: An Evaluation of Select Categories of Packaged Foods in the United States, 2018

BACKGROUND

Lowering excess sodium in packaged foods is part of a public health strategy to reduce cardiovascular disease risk. Sales of foods with labeled sodium claims increased during the past decade. Yet, it is unclear whether sugars or fats were added during the reformulation of foods that might counter the benefits of sodium reduction.

OBJECTIVE

It was hypothesized that the nutrient content of packaged foods with lower sodium label claims (ie, sodium-modified) would differ from their regular (ie, unmodified) counterparts.

DESIGN

This cross-sectional study compared label data of 153 sodium-modified foods and 141 regular, matched counterparts within four food categories: soups, processed meats, vegetables, and savory snacks. Foods were identified by searching manufacturer websites of the top-10 brands in each category. Sodium, calories, total carbohydrate, sugar, protein, total fat, saturated fat, and potassium (when reported) were compared by labeled serving and per 100 g food.

RESULTS

The average amount in milligrams of sodium per serving in regular foods ranged from 162 mg for savory snacks to 782 mg for soups. Compared with regular foods, the matched lower sodium foods had significantly less sodium per serving (-95 to -387 mg) and per 100 g (-184 to -462 mg) (P<0.01 for all comparisons), except for soups per 100 g (P = 0.166), and were similar to their regular counterparts in calories, total carbohydrate, sugar, protein, total fat, and saturated fat (P>0.05 for all comparisons). Of the soups that reported potassium on the label, potassium was 244 mg/serving (P=0.004) and 139 mg/100 g (P=0.002) higher among matched lower sodium soups.

CONCLUSIONS

The similarity in macronutrient contents on the labels for sodium-modified foods and their regular counterparts suggests that reformulation did not include the addition of significant amounts of sugars, fats, or other macronutrients among major food brands in the selected categories. Potassium content and additional food categories deserve further investigation.

Potassium-Enriched Salt Substitutes as a Means to Lower Blood Pressure: Benefits and Risks

Use of salt substitutes containing potassium chloride is a potential strategy to reduce sodium intake, increase potassium intake, and thereby lower blood pressure and prevent the adverse consequences of high blood pressure. In this review, we describe the rationale for using potassium-enriched salt substitutes, summarize current evidence on the benefits and risks of potassium-enriched salt substitutes and discuss the implications of using potassium-enriched salt substitutes as a strategy to lower blood pressure. A benefit of salt substitutes that contain potassium chloride is the expected reduction in dietary sodium intake at the population level because of reformulation of manufactured foods or replacement of sodium chloride added to food during home cooking or at the dining table. There is empirical evidence that replacement of sodium chloride with potassium-enriched salt substitutes lowers systolic and diastolic blood pressure (average net Δ [95% CI] in mm Hg: -5.58 [-7.08 to -4.09] and -2.88 [-3.93 to -1.83], respectively). The risks of potassium-enriched salt substitutes include a possible increased risk of hyperkalemia and its principal adverse consequences: arrhythmias and sudden cardiac death, especially in people with conditions that impair potassium excretion such as chronic kidney disease. There is insufficient evidence regarding the effects of potassium-enriched salt substitutes on the occurrence of hyperkalemia. There is a need for additional empirical research on the effect of increasing dietary potassium and potassium-enriched salt substitutes on serum potassium levels and the risk of hyperkalemia, as well as for robust estimation of the population-wide impact of replacing sodium chloride with potassium-enriched salt substitutes.