Potassium chloride
A mineral salt used as a low-sodium salt substitute and food preservative, found in reduced-salt products across supermarkets.
Potassium chloride contributes to total dietary potassium. People with kidney disease or on potassium-controlling medication should monitor intake from reduced-salt products, which can carry significant amounts.
What is it?
Potassium chloride is an inorganic mineral salt, the potassium counterpart to sodium chloride (table salt). It occurs naturally in many foods and is also produced commercially for use as a food additive and in medical settings (including intravenous electrolyte solutions).
What does it do?
As a food additive, it replaces some or all of the sodium chloride in a recipe to reduce sodium content while preserving a salty flavour, though at high levels it can add a slightly bitter or metallic taste. It also functions as a firming agent, gelling aid, and helps control water activity to inhibit microbial growth in some preserved foods.
Where you will see it
Most commonly found in low-salt or reduced-sodium versions of bread, processed cheese, ready meals, crisps, soups, sausages, cured meats, and table salt blends sold as 'Lo-Salt' or similar. On the label it appears as 'potassium chloride' or 'E508'.
What the science says
Kidney disease and potassium accumulation
Healthy kidneys filter and excrete excess potassium efficiently. In people with chronic kidney disease (CKD) or those on certain medications such as ACE inhibitors, angiotensin receptor blockers, or potassium-sparing diuretics, this filtration is impaired. Consuming large quantities of potassium chloride from reduced-salt foods can push potassium levels to dangerous heights, a condition called hyperkalaemia, which can cause irregular heart rhythm and, in severe cases, cardiac arrest.
Chronic kidney disease impairs potassium excretion; dietary potassium from salt substitutes contributes to hyperkalaemia risk in this population.
Salt substitutes containing potassium chloride have been associated with acute hyperkalaemia in patients with CKD or taking renin-angiotensin-aldosterone system inhibitors in case series and observational studies.
Cardiovascular benefit in the general population
For people without kidney disease, replacing some dietary sodium with potassium is associated with lower blood pressure and reduced cardiovascular risk. Large randomised trials and meta-analyses support this effect. The benefit arises from potassium's role in relaxing blood vessel walls and promoting sodium excretion through the kidneys.
Potassium supplementation reduced systolic blood pressure by an average of 3.5 mmHg in a meta-analysis of randomised controlled trials.
A large randomised trial in China (the SSaSS trial) found that replacing regular salt with a potassium chloride blend reduced stroke, major cardiovascular events, and death in people with high cardiovascular risk.
Taste effects at high concentrations
At high replacement levels, potassium chloride introduces a bitter or metallic off-taste that limits how much sodium it can practically replace in reformulated foods. Food manufacturers often use flavour masking agents alongside it or blend it with smaller amounts of sodium chloride to stay within the acceptable taste range.
Sensory panels consistently detect bitter and metallic notes from potassium chloride at concentrations above around 0.3-0.5% in aqueous solutions, limiting full sodium replacement.
Where it stands with the regulators
Who should be careful
People with chronic kidney disease, those on dialysis, or anyone taking potassium-sparing diuretics, ACE inhibitors, or angiotensin receptor blockers should take care with products that list 'potassium chloride' or 'E508', particularly reduced-salt or low-sodium versions of bread, soups, crisps, and processed meats. Look for 'potassium chloride' or 'E508' in the ingredients list, and check with your GP or renal dietitian if in doubt.
The honest read
For people with healthy kidneys, potassium chloride in food is a straightforward mineral and there is substantial evidence it is better for blood pressure than the sodium it replaces. The concern is real but it is specific: people with kidney disease or on certain heart or blood pressure medications can accumulate potassium to dangerous levels, and reduced-salt processed foods can carry a meaningful amount. The science distinguishing who is at risk is well established and not contested. For everyone else, the additive is entirely ordinary.
Related additives
Common questions
Is E508 banned in the UK?
No. Potassium chloride (E508) is approved for use in the UK under the UK FSA approved-additives list and the assimilated EU Regulation 1333/2008. It is permitted in a wide range of food categories.
Should I avoid E508 if I have kidney disease?
If you have chronic kidney disease or are on potassium-controlling medication, you should be careful about products with 'potassium chloride' or 'E508' on the label. These reduced-salt foods can add significantly to your daily potassium load. Speak to your GP or renal dietitian about how much is appropriate for you.
What foods contain E508?
E508 is most common in reduced-salt or low-sodium products including bread, crisps, soups, ready meals, processed cheese, cured meats, and table salt blends such as Lo-Salt. Check the ingredients list for 'potassium chloride' or 'E508'.
Is E508 vegan?
Yes. Potassium chloride is a mineral salt with no animal-derived ingredients and is suitable for vegans and vegetarians.
Sources
- UK FSA Approved Additives and E Numbers
- Neal B et al., Effect of Salt Substitution on Cardiovascular Events and Death (SSaSS), New England Journal of Medicine
- Aburto NJ et al., Effect of increased potassium intake on cardiovascular risk factors and disease, British Medical Journal
- Chang AR et al., High dietary phosphorus intake is associated with all-cause mortality: results from NHANES III, American Journal of Clinical Nutrition
- Sinopoli DA, Lawless HT, Potassium chloride in salt mixtures, Journal of Food Science
- NHS Clinical Knowledge Summaries: Hyperkalaemia
- EU Regulation 1333/2008 on food additives (Annex II)
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