A major randomized clinical trial has shown how reducing dietary sodium levels, including through potassium salt intake, can help reduce blood pressure as well as the risks of heart attack, cardiovascular events, and premature mortality from various causes.
The research, published in The New England Journal of Medicine (Neal et al., 2021), was conducted in 600 villages in rural China among 20,995 individuals over-60 with hypertension (88.4%) and prior heart attacks (72.6%), with an average follow-up of 4.74 years. (1)
Excess salt, potassium deficiency
Excess salt (sodium chloride), as noted, is a risk factor for several chronic diseases-including diabetes-and premature mortality. WHO has developed a baseline standard for various foods, with the goal of reducing daily salt consumption to below 5 grams (2 grams of sodium), by 2025, to mitigate the incidence of diseases related to its excess. (2)
Potassium deficiency, which is directly related to excessive intake of salt (and other sources of sodium, e.g., glutamate) is itself a risk factor for various adverse health effects. High blood pressure first of all, caused precisely by the imbalance between sodium and potassium intakes. (3)
Potassium chloride is one of the most promising salt substitutes because of its ability to supplement the dietary intake of this mineral by replacing and removing the excess sodium normally present, benefiting health and not especially blood pressure. (4)
Possible contraindications
Excessive consumption of potassium can result in the development of hyperpotassemia, that is, an elevated plasma concentration. Which in turn could lead to risks of arrhythmia and muscle weakening. However, the most recent studies consider the benefits of potassium-beneficial to the kidneys, heart, and blood pressure-to outweigh the possible risks. (5)
From a sensory point of view, potassium chloride has an unusual, slightly bitter and metallic taste. Nevertheless, a previous randomized double-blind study (Maleki et al., 2016) found good acceptance, 80 percent, of various salt substitutes with sodium reduction and potassium addition. Their use in food preparations and processed foods allows for flavor balance with other ingredients in each case. (6)
Clinical study, results
The Salt Substitute and Stroke Study. (SSaSS, Neal et al., 2017-2021) was designed for the purpose of large-scale evaluation of the overall benefits and risks of replacing common table salt with a substitute for it, composed of sodium chloride and potassium chloride (in proportions 75-25% by mass). (7)
The clinical trial showed a significant reduction in stroke cases in the group given the aforementioned salt substitute, compared with the control group that continued to consume sodium chloride instead. This finding also assumes relevance in the prevention of potentially fatal complications of cardiovascular disease and acute coronary syndrome.
Sodium reduction and potassium increase were confirmed to underlie the observed effects, with primary effect on blood pressure. Conversely, no evidence of increased risks of hyperpotassemia and associated arrhythmia was identified. Therefore, researchers have corroborated the benefits of using salt substitutes.
Potassium chloride, EU rules
The characteristics of potassium chloride-in terms of shape, odor and color-are similar to those of common table salt. It is currently authorized in the EU as a food additive under E 508 at the quantum satis dose (EC Reg. No. 1333/08). The safety of its intake, at the doses normally used, was confirmed by EFSA (2019) in a recent re-evaluation. (8)
One exception is the requirement for its authorization in the preparation of food for infants, early childhood, special medical purposes and substitutes for the weight control ration (EU Reg. No. 609/2013). As well as for food fortification to address mineral salt deficiencies or improve the nutritional status of the population (EC Reg. 1925/2006).
Evolving scientific knowledge about the nutritional role is another requirement for the possible addition of potassium chloride in foods. With this in mind, several food industry players have adopted a common position. Aiming to obtain recognition of the possibility of using potassium chloride, to be marketed as ‘potassium salt,’ as a partial replacement for table salt. (9)
Interim conclusions
Partial replacement of table salt with potassium chloride is presented as an effective strategy in reducing excessive sodium intake and preventing related diseases. The possible health contraindications and sensory acceptability appear very small compared to the potential benefits, which conversely appear much more important both quantitatively and qualitatively.
Further research is in any case needed to validate the safety of potassium chloride use on a larger scale. On this basis, it will be possible to consider regulatory revisions and the promotion of the use of ‘potassium salt,’ currently very expensive, as a promising alternative to sodium chloride.
Dario Dongo and Andrea Adelmo Della Penna
Notes
(1) Neal et al. (2021) Effect of Salt Substitution on Cardiovascular Events and Death. The New England Journal of Medicine, https://doi.org/10.1056/NEJMoa2105675
(2) WHO. WHO global sodium benchmarks for different food categories. 3.5.21, ISBN 9789240025097, https://www.who.int/publications/i/item/9789240025097 (accessed 3.9.21).
(3) Perez et al. (2014). Sodium-to-Potassium Ratio and Blood Pressure, Hypertension, and Related Factors. Adv. Nutr. 5(6):712-741, https://doi.org/10.3945/an.114.006783
(4) Greet et al. (2020). Potassium-enriched salt substitutes as a means to lower blood pressure: benefits and risks. Hypertension 75(2):266-74, https://doi.org/10.1161/HYPERTENSIONAHA.119.13241
(5) Wei et al. (2020). Dietary potassium and the kidney: lifesaving physiology. Clin. Kidney J. 13(6):952-968, https://doi.org/10.1093/ckj/sfaa157
(6) Maleki et al. (2016). The flavor and acceptability of six different potassium-enriched (sodium reduced) iodized salts: a single-blind, randomized, crossover design. Clinical Hypertension 22:18, https://doi.org/10.1186/s40885-016-0054-9
(7) Neal et al. (2017). Rationale, design, and baseline characteristics of the Salt Substitute and Stroke Study (SSaSS)-a large-scale cluster randomized controlled trial. Am. Heart J. 188:109-17, https://doi.org/10.1016/j.ahj.2017.02.033
(8) EFSA FAF Panel et al. (2019). Re-evaluation of hydrochloric acid (E 507), potassium chloride (E 508), calcium chloride (E 509) and magnesium chloride (E 511) as food additives. EFSA Journal 17(7):5751, https://doi.org/10.2903/j.efsa.2019.5751
(9) Culinaria Europe. Joint Position paper on Potassium chloride used as salt substitute. 21.8.18, https://www.culinaria-europe.eu/download/joint-pp-kcl-final-2018-08-21.pdf
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
Graduated in Food Technologies and Biotechnologies, qualified food technologist, he follows the research and development area. With particular regard to European research projects (in Horizon 2020, PRIMA) where the FARE division of WIISE Srl, a benefit company, participates.
