Potassium chloride

also: KCl · Potassium salt · Salt substitute (component)

The potassium version of table salt, used to cut sodium in reduced-salt foods. Good for most people's blood pressure, but a risk for people with kidney disease.

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An ingredient list from the crisps and savoury snacks aisle

Wholegrain Brown Rice (75%) · Rapeseed Oil · Sugar · Dextrose · Maltodextrin · Salt · Potassium Chloride. Contains salt substitute Potassium Chloride.

E508Mineral

Potassium chloride

Potassium chloride adds to total potassium.

VeganVegetarian

867

of the 43,325 UK supermarket foods we checked declare E508 in their ingredients

That is 2%, counted by its code or its name.

Only 1.6% of these labels print “E508”. Most use the name: look for “potassium chloride”.

Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted

How common it is in UK food, by aisle

Crisps and savoury snacks401 products12% of 3,428
Fresh meat, poultry and fish89 products1.8% of 4,835
Ready meals and pizza71 products1.5% of 4,833
Sauces, dressings and condiments64 products2.3% of 2,776

What potassium chloride is, what it does and where you will see it

Why it’s worth knowing. Potassium chloride adds to total potassium. People with kidney disease, or on medicines that affect potassium, should watch how much they get from reduced-salt products, which can carry a lot of it.

What is it?

Potassium chloride is a mineral salt, the potassium version of sodium chloride (table salt). It is found naturally in many foods and is also made for use in food and medicine, including drips given in hospital.

What does it do?

It replaces some or all of the table salt in a recipe, cutting sodium while keeping a salty taste, though in large amounts it tastes a little bitter or metallic. It also firms food, helps it set, and leaves less free water for microbes in some preserved foods.

Where you will see it

Mostly in low-salt or reduced-sodium bread, processed cheese, ready meals, crisps, soups, sausages and cured meats, and in salt blends such as Lo-Salt. Labels call it potassium chloride or E508.

What the science says

A risk for people whose kidneys cannot clear potassium

Healthy kidneys get rid of extra potassium easily. In people with long-term kidney disease, or on certain medicines such as ACE inhibitors, angiotensin receptor blockers or potassium-sparing diuretics, that is impaired. Eating a lot of potassium chloride from reduced-salt foods can push blood potassium dangerously high, a condition called hyperkalaemia, which can upset the heart's rhythm and in severe cases stop the heart.

Long-term kidney disease makes it harder to clear potassium, and potassium from salt substitutes adds to the risk of hyperkalaemia in these people.

NHS guidanceNHS Clinical Knowledge Summaries: Hyperkalaemia

Case series and observational studies have linked salt substitutes containing potassium chloride to sudden hyperkalaemia in people with kidney disease or taking certain blood pressure medicines.

2006ObservationalChang et al., American Journal of Medicine

For most people, swapping sodium for potassium lowers blood pressure

For people without kidney disease, replacing some sodium with potassium is linked to lower blood pressure and less heart and circulation disease. Large randomised trials and reviews of many trials support this. Potassium helps blood vessel walls relax and helps the kidneys get rid of sodium.

In a review of randomised trials, extra potassium lowered the top blood pressure number by an average of 3.5mmHg.

2013Review of many trialsAburto et al., British Medical Journal

A large randomised trial in China (the SSaSS trial) found that swapping ordinary salt for a potassium chloride blend cut strokes, major heart events and deaths in people at high risk of heart disease.

2021Randomised trial in peopleNeal et al., New England Journal of Medicine

Too much tastes bitter

In large amounts potassium chloride tastes bitter or metallic, which limits how much salt it can replace. Makers often add flavour maskers or blend it with some ordinary salt to keep the taste acceptable.

Taste panels consistently pick up bitter and metallic notes from potassium chloride above about 0.3 to 0.5% in water, which limits replacing all the sodium.

2012Lab studySinopoli & Lawless, Journal of Food Science

Where it stands with the regulators

Approved in the UK and the EU

Daily limit. None set.

Legal basis: On the Food Standards Agency's approved list for Great Britain
Permitted foods: Bread and baked goods · Processed cheese · Tinned and bottled vegetables · Cured and processed meats · Ready meals · Soups · Snacks and crisps · Table salt blends
Maximum levels: No set maximum in most foods, as long as makers use no more than they need.
History: Potassium chloride has a long history in food and medicine and has not been restricted or re-reviewed over safety in the EU or UK. It is also on the US FDA's GRAS list of long-used substances. There are no bans or warning labels. Regulators have focused on labelling that alerts kidney patients, not on the additive itself.

Who should be careful

People with long-term kidney disease, people on dialysis, and anyone taking potassium-sparing diuretics, ACE inhibitors or angiotensin receptor blockers should take care with products listing potassium chloride or E508, especially reduced-salt bread, soups, crisps and processed meats. Check with your GP or kidney dietitian if you are unsure.

The honest read

For people with healthy kidneys, potassium chloride is a plain mineral, and there is good evidence that swapping sodium for it helps blood pressure. The risk is real but specific: people with kidney disease, or on certain heart or blood pressure medicines, can build up potassium to dangerous levels, and reduced-salt processed food can carry a meaningful amount. Who is at risk is well understood and not disputed.

Common questions about potassium chloride

Is E508 banned in the UK?

No. Potassium chloride is approved in the UK and allowed in a wide range of foods.

Should I avoid E508 if I have kidney disease?

If you have long-term kidney disease or take medicine that affects potassium, be careful with products listing potassium chloride or E508. Reduced-salt foods can add a lot to your daily potassium. Ask your GP or kidney dietitian how much is right for you.

What foods contain E508?

Mostly reduced-salt or low-sodium products, including bread, crisps, soups, ready meals, processed cheese, cured meats and salt blends such as Lo-Salt.