A functional food approach to salt reduction has the potential to make big differences in sodium dietary intake and, therefore, population health, and may be a quicker and more effective option than other approaches to sodium reduction according to Karppanen et al.,(1) The original arguments for this approach from the University of Helsinki are brought up-to-date with evidence from more recent science that justifies this proposition (2).
The evidence linking dietary salt to blood pressure has been exhaustively reviewed in the scientific literature. Public health policy implications of the evidence have been considered by expert committees in many countries and by influential scientific bodies within such organisations as the World Health Organization (3). Overwhelmingly the evidence supports the fact that despite sodium being an essential mineral, our current high intakes from salt (sodium chloride) are not necessary and for some, may increase the risk of hypertension and other non-communicable diseases (4).
The use of functional foods that correct the mineral composition of processed foods, cooking salts or seasonings by replacing or reducing sodium with potassium, calcium and magnesium salts has been suggested as a means of addressing both the dominance of sodium, and the mineral inadequacies or imbalances of minerals in our diets (1).
Addressing the mineral imbalances in our diets
Poor diet is responsible for more deaths than any other risks globally, including tobacco smoking. It is known that the sub-optimal intake of just 3 dietary factors account for more than 50% of diet-related deaths and 66% of diet-related life years lost to ill health, disability or early death. These dietary factors are too much sodium and too little wholegrains and fruit (5).
It is well known that the average sodium intake from salt in industrialised populations exceeds recommended levels which leads to a greater risk of high blood pressure. We also know that present dietary intakes of potassium and magnesium are lower than recommended levels in the same populations. Data from the European Nutrition and Health Report and The United States Department of Agriculture indicates that only 25-50% of people have an adequate intake of many micronutrients and that 25-75% have a dietary intake that is less than the recommended daily allowance (micronutrient dependent). For example in Europe, intakes were inadequate for magnesium in children >10 years and all adults (6).
Dietary approaches to sodium reduction
Decreased intake of sodium and increased intakes of potassium alone are known to decrease elevated blood pressure and the most pronounced effects are brought about by a combination of reduced sodium and increased minerals such as potassium and magnesium (1).
A move to DASH (Dietary Approaches to Stop Hypertension) dietary recommendations, which shifts eating patterns to include more fruit, vegetables, seeds, nuts and fish and less high fat dairy, red meat and snacks would significantly change dietary mineral balance for populations. Several studies have shown that the DASH diet lowers high blood pressure as effectively as most blood pressure drugs, prolongs life, and prevents heart attacks and strokes. The most common explanation for this success has been the high potassium, magnesium and fibre content of vegetables. However such large changes in dietary habits have proven to be difficult and slow. Only 2 percent of the US population follow these dietary principles despite the recommendation of the American Heart Association (7). The DASH diet is often seen as only for people with high blood pressure and is perceived as difficult to implement because of affordability and accessibility to DASH-accordant foods (7,8).
Alternatively it has been proposed that processed foods are replaced with non-processed, natural foods. This approach would also have a dramatic effect on the intake of minerals and although we have seen a resurgence of “cooking from scratch” during the COVID-19 pandemic, the use of processed food items in industrialised countries is still increasing.
According to Karppanen et al.,(1),
“Correcting the composition of extensively used processed foods by reducing sodium and addressing the balance of other minerals is one of the easiest ways to change the composition of the processed food items that a population most likes and is used to eating. It has been suggested that this approach is effective as it does not require any effort from the population and practically all individuals receive the beneficial treatment”.
In this regard it is sensible to target some of the highest contributors to sodium in the diet to obtain a decrease in sodium with an enrichment with potassium and magnesium (1).
Feasibility and Proof of Concept
Observational studies and randomized controlled trials have confirmed that dietary salt reduction can lower blood pressure in both hypertensive and normotensive patients (9,10) . In addition, higher intakes of potassium are associated with decreased blood pressure independent of sodium intake (11).
Since the 1980’s salt substitutes/alternatives based on potassium and magnesium salts have been studied in both epidemiological and clinical trials which have explored this approach on lowering blood pressure. Peng et al., (12) conducted a meta-analysis of all the randomised controlled trials to evaluate the effect of salt substitutes on blood pressure. The results indicated that salt substitution strategies are effective at lowering systolic blood pressure and diastolic blood pressure, which supports a nutritional approach to preventing hypertension.
Although the systematic review and meta-analysis of salt substitution showed large effects on blood pressure, the trials were of relatively short duration and small cohorts. There have been some concerns about the potential increased risk of hyperkalemia if this dietary strategy is used over a longer period of time including arrhythmias and sudden cardiac death (13)
The recent Salt Substitute and Salt Study (SSaSS) has addressed some of these concerns. In contrast to many of the attempts to estimate the effects of sodium reduction or potassium supplementation on cardiovascular disease the SSaSS trial used robust randomised design with a very large population-based cohort over 5 years follow-up. 20,995 people from 600 villages in rural China, who were 60 years of age or older and had high blood pressure, were randomly assigned to either a regular salt group (100% sodium chloride by mass) or a salt substitute group which contained 25% potassium chloride ( 75% sodium chloride, 25% potassium chloride by mass) . The follow-up period was 5 years and the primary outcome was stroke, the secondary outcomes were major adverse cardiovascular events and death from any cause, and the safety outcome was clinical hyperkalemia. The results indicated that the use of the salt substitute among persons who had a history of stroke or were 60 years or older with high blood pressure reduced the rates of stroke, major cardiovascular events, and death from any cause, with no apparent serious adverse effects (14). Dr Bruce Neal, who was co-author of this study, has been quoted as saying that,
“If you were to replace all of the salt on the supermarket shelves with salt substitutes, you would prevent thousands of strokes and heart attacks every year – that’s quite safe to say” (15).
Technical feasibility and Consumer Acceptance
The technical challenges for the industry are well known and include the maintenance of taste, preservation and functionality within food systems whilst reducing multifunctional sodium chloride and other widely used sodium salts (16).
Reducing sodium is often a multi-dimensional task involving:
- Taste – affects consumer acceptance and purchasing behaviour
- Preservation – affects shelf-life and public safety
- Functionality – affects processing and product quality
There are salt substitutes/replacers that are commercially available based on balanced mixtures of minerals such as potassium and magnesium that are already helping food manufacturing businesses to apply the functional food approach to sodium reduction (16). It is possible to do this without the need for extensive new product development, as in many cases the mineral-based products can be used as direct one- to–one replacers (weight basis) for added sodium chloride (16). These salt replacers have been shown to be successful in terms of maintaining organoleptic quality and microbiological safety in many processed foods including those that are major contributors to sodium intake (18-21). These replacers are now available directly to both the food manufacturing industry and consumers so they can be used in home-cooking and in populations that do not rely so heavily on processed foods (17).
The UK initiatives to reduce population consumption of salt rely very heavily on the food industry to voluntarily reduce salt in food products to pre-set salt targets by product category (22). Targets have been set so that compliance with these standards would ensure meaningful reduction in sodium intake levels being met at population level. In this way it is hoped that the health of the nation will be improved, mainly through reduction in hypertension, cardiovascular disease and stroke, with the associated reduction in health-care costs. Although the food industry in the UK has responded well, sodium reduction in processed foods has slowed down in recent years and population targets have not been met. Hence the call by Action on Salt to make sodium reduction targets mandatory for the food industry (23) which would provide a “level playing field” in which the food industry could operate.
Since many of the food technology issues surrounding sodium and salt replacement are understood and resolvable with balanced mineral salt mixtures, a functional food approach to salt reduction to include mineral salts such as potassium and magnesium is possible and has the potential to make big differences in dietary intake and population health and as a result may be a quicker option than other approaches to sodium reduction.
- Karpannen et al., 2005. Why and how to implement sodium, potassium, calcium and magnesium changes in food items and diets. Journal of Human Hypertension 19, S10-19
- Mitchell H., 2019 Dietary Sodium Reduction: A Functional Food Approach. Paper given at Food Matters Live 19-20 November - What are the drivers and opportunities shaping the future of heart health.
- World Health Organization. Global Action Plan for the prevention and control of noncommunicable diseases 2013-2020. World Health Organization;2013
- World Health Organization. Guideline : Sodium intake for adults and children. World Health Organization :2012
- Murray et al., 2019. Health effects of dietary risks in 195 countries, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. The Lancet 393:1958-72
- Gombart AF et al., A Review of Micronutrients and the Immune System- Working in harmony to Reduce the Risk of Infection. Nutrients 2020 Jan16; 12(1):236, doi: 10.3390/nu12010236
- DASH Diet for Weight Loss | Cooking Light
- Evidence-Brief-13-DASH-diet-v1.0-01.02.17-1.pdf (cam.ac.uk)
- He FJ et al., Effect of longer-term modest salt reduction on blood pressure. Cochrane Database Syst Rev 2013;4;CD004937
- Strazzullo P et al., Salt intake, stroke and cardiovascular disease: meta-analysis of prospective studies. BMJ 2009;339:b4567
- Aburto NJ et al., Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analysis. BMJ, 2013;346:f1378
- Peng Ya-Guang et al., 2014 Effects of salt substitutes on blood pressure: a meta-analysis of randomized controlled trials. Am J Clin Nutr 100:1448-54
- Greer RC et al., 2020 Potassium-Enriched Salt Substitutes as a Means to Lower Blood Pressure. Hypertension 75 (2) 266-274
- Neal B et al., 2021 Effect of Salt Substitution on Cardiovascular Events and Death. N Eng J Med 2021;385;1067-77
- Health discovery: Salt substitute 'could prevent thousands of strokes and heart attacks' - Wales Online
- Mitchell, H., 2015 . Low Sodium Diets Need Smart Reduction Strategies. Innovations in Food Technology, February
- Mitchell, H., 2013. Balancing Minerals for Good Health. Innovations in Food Technology, February.
- Mitchell, H., 2014 (a). Be Smart With Minerals. Innovations in Food Technology, February.
- Mitchell, H., 2014(b). Smart Salt: Tastes like Salt, Preserves like Salt, Handles like Salt. Innovations in Food Technology, November.
- Mitchell, H and Komitopoulou, E, 2013. Microbial effects of replacing sodium chloride with a magnesium-containing mineral salt in white bread. AgroFood Industry HiTech, 23(2).
- Salt reduction: targets for 2024 - GOV.UK (www.gov.uk)
- Call for mandatory salt reduction in British food - Wales Online