Lower-sodium salt substitutes: who should check before switching?

What is replacing the sodium?

Ordinary salt is sodium chloride. Many substitutes replace part of it with potassium chloride. The WHO's 2025 guideline describes blood-pressure benefits from this combination, partly attributable to potassium. The products still contain sodium, so using more can undermine the intended reduction.

For a real UK example, LoSalt describes its product as a sodium-chloride and potassium-chloride blend with 66% less sodium than regular salt. That is a product comparison, not a claim of 66% less sodium across your entire diet. Nor is it the same formulation as the 25% potassium-chloride mixture used in the large trial below.

A pink colour or coarse texture does not establish this substitution. North Bristol NHS Trust's kidney-diet guidance includes sea, rock and Himalayan salts among added salts to limit. Its advice is written for people with kidney disease, but the distinction is relevant to shopping: a different-looking ordinary salt is not automatically lower in sodium.

Look for potassium chloride in the ingredients, the sodium-reduction comparison, and any medical warning. Keep those three pieces of information together. A prominent percentage on the front cannot tell you whether the product is suitable with your medicines.

Why do your kidneys matter?

The kidneys normally remove excess potassium in urine, as the National Kidney Foundation explains. Reduced kidney function can make that clearance harder. Some medicines also increase the amount retained, which is why kidney health and the prescription list belong in the same conversation.

High blood potassium is called hyperkalaemia. East and North Hertfordshire NHS information explains that it often has no obvious symptoms, yet can cause dangerous heart-rhythm problems. Feeling well is not a reliable way to check whether the extra potassium is safe.

Blood pressure and blood potassium are different measurements. A lower cuff reading after changing food does not establish that potassium handling is safe. If a clinician needs to assess potassium, they use the appropriate blood test and clinical context rather than the blood-pressure monitor.

Which medicines should prompt a check?

South Tees Hospitals NHS guidance advises avoiding salt substitutes with ACE inhibitors and angiotensin receptor blockers because potassium can become dangerously high. Examples include:

• ACE inhibitors: ramipril, lisinopril and perindopril.
• Angiotensin receptor blockers, often shortened to ARBs: losartan, candesartan and valsartan.

Potassium-sparing diuretics are another important group. The losartan prescribing information names amiloride, triamterene and spironolactone among medicines that retain potassium, and also identifies potassium supplements and potassium-containing salt substitutes as relevant combinations. The NHS spironolactone page specifically warns that substitutes such as Lo-Salt can raise potassium further.

These examples help you recognise a reason to ask, but are not a complete interaction checker. Show a pharmacist or prescriber the actual product and your full medicine and supplement list. Combination tablets can contain more than one medicine, so use the packet names rather than relying on memory.

A useful question is: 'Is this potassium-containing substitute suitable with my medicines and kidney health, and does using it require any monitoring?' Mention whether you would use it in shared cooking, how often, and whether you already take a potassium supplement.

Keep taking prescribed medicines as directed. Stopping a treatment to make room for a salt substitute reverses the decision you are trying to make. If the product is unsuitable, reducing ordinary added salt and comparing food labels remain available approaches.

Does the general recommendation apply to you?

WHO conditionally suggests that adults choosing to use table salt replace it with a potassium-containing lower-sodium substitute within an overall sodium-reduction strategy. Its recommendation excludes children, pregnant women, and people with kidney impairment or other circumstances that compromise potassium excretion. It applies to salt added in cooking or at the table, rather than endorsing all manufactured foods containing substitutes.

The conditional status reflects low overall evidence certainty and uncertainty about harms, including unrecognised contraindications. Being outside that recommendation is not proof that every excluded person will be harmed; it means the general recommendation should not be used as their permission to switch.

For someone with a relevant condition, individual advice needs to resolve the question before a household change. You do not need a potassium product in order to cook with less added salt.

Check before changing the household salt

If someone has been advised to avoid extra potassium, changing the salt in a casserole affects them even if they never use the salt shaker. WHO explicitly advises against preparing shared food with the substitute for a household member at risk of hyperkalaemia.

Keep the product in its labelled container. If several people cook, make sure they know which salt is being used and whose dietary advice applies. A substitute decanted into an ordinary salt pot removes information that may matter to another person.

This also applies when preparing meals for a relative. Their prescription may have changed since you last cooked for them. Check the current instructions rather than treating a product that suits you as a default for their meals.

How much did substitution reduce stroke rates?

The Salt Substitute and Stroke Study involved 20,995 adults in 600 rural Chinese villages. Participants had a previous stroke, or were at least 60 with poorly controlled blood pressure. Villages used regular salt or a 75% sodium-chloride, 25% potassium-chloride blend, with average follow-up of 4.74 years.

Stroke rates were 29.14 versus 33.65 per 1,000 person-years: about 4.5 fewer events per 1,000 years of participant follow-up, and a roughly 14% lower rate. One thousand person-years could mean 1,000 people followed for one year. This is a rate comparison, not a 14-percentage-point reduction in an individual's risk.

The substitute was provided for household cooking, seasoning and preservation. People eating most meals elsewhere were excluded, as were those whose own or household member's serious kidney disease, potassium supplements or potassium-sparing diuretics raised concern.

Serious events attributed to high potassium were not significantly more frequent, but routine potassium blood tests were absent. Unnoticed biochemical increases were therefore possible. Australian public research funding supported the study; the manufacturer donated substitute during years three and four.

For a younger UK adult who rarely adds salt, the opportunity may be much smaller. The practical inference is to identify what would actually be replaced before assuming that a striking trial result applies to the salt shaker in your kitchen.

What happened when researchers measured blood potassium?

DECIDE-Salt studied 1,612 residents in 48 Chinese elderly-care facilities over two years. Compared with usual salt, substitution lowered systolic pressure by about 7.1 mmHg. It also raised average blood potassium and increased biochemical hyperkalaemia: among residents with follow-up blood assays, the figures were 7.0% versus 2.4%.

The study reported no evidence of associated adverse clinical outcomes. That wording does not mean no adverse events happened. Its full accepted manuscript describes repeat potassium checks, heart tracing when needed and clinician-directed withdrawal. Unlike the stroke study, it managed potassium-risk participants through monitoring rather than excluding all such groups.

The blood-pressure benefit and potassium finding can both be true. A trial with clinical monitoring is not the same situation as buying a product and assuming that a favourable pressure reading settles its safety.

What if most of your salt comes from food you buy?

The NHS advises adults to have no more than 6 g salt daily, including salt already in food. It estimates that around three quarters comes from packaged and everyday foods such as bread, cereals, meat products and ready meals. Changing added salt addresses only the part you replace.

Look at a typical day's repeat purchases: the sandwich, soup, sauce, stock and main meal. Compare similar products per 100 g, then calculate the portion you eat. This can reveal a larger opportunity than changing an ingredient you use only occasionally.

For illustration, a 400 g meal containing 0.8 g salt per 100 g supplies 3.2 g. A similar-sized meal with 0.5 g per 100 g supplies 2 g. The difference is 1.2 g for the whole pack. These are example labels showing the calculation, not current values for a named meal.

The NHS also highlights a less obvious source: some dissolvable painkillers, vitamins and prescribed medicines can contain substantial salt. If you use these regularly, ask a pharmacist about the formulation. Do not change prescribed treatment on your own.

If you are monitoring blood pressure, keep the agreed record while making changes. Our home-measurement guide explains the setup and recording process. Send the results for the planned review and leave medication decisions with your prescriber; the food change and the treatment plan should be considered together.