Salt and Sodium

Salt and sodium. What is the difference?

Salt and sodium are not the same thing, but they are closely related.

Salt (sodium chloride, NaCl) is the crystalline compound used in cooking and food manufacturing. It is made up of approximately 40% sodium and 60% chloride by weight.

Sodium is the element within salt that causes the health effects. It is the sodium component, not the chloride, that raises blood pressure and drives the associated risks.

Food labels in the UK typically display salt content rather than sodium content. This is more straightforward for most people, since it allows direct comparison with the 6g daily limit without conversion. Some older labels, and products imported from outside the UK, may show sodium rather than salt. To convert: multiply sodium by 2.5 to get the equivalent salt content.

How much is 6g of salt?

6g of salt is equivalent to approximately one teaspoon. Which sounds like a lot until you start checking labels and realising how quickly it accumulates across a day of ordinary eating. A single bowl of tinned tomato soup can contain 2 to 3g of salt. Two slices of bread add around 1g. A ready meal may add another 2g or more. By mid-afternoon many people have already exceeded the daily limit without touching the salt shaker.

The UK recommendations

The official UK limit: 6g per day for adults

The SACN Salt and Health report (2003) recommended that UK population salt intake should be reduced to 6g per day for adults. This recommendation was adopted by the UK government and remains the basis of NHS guidance. It applies to adults from the age of 11.

Infants under 12 months should have no added salt at all; their kidneys cannot process it safely.

The WHO recommendation: no more than 5g per day

The World Health Organization sets its target slightly lower than the UK at 5g of salt per day (equivalent to 2g of sodium), which it describes as one of the most cost-effective health interventions a country can implement. The UK's 6g limit reflects what was considered practically achievable in 2003 rather than the maximum health benefit, which would come from further reductions.

Where the UK population actually sits

According to the National Diet and Nutrition Survey (NDNS), UK adults were eating approximately 8.4g of salt per day as of 2018, around 40% above the 6g limit. This followed a period of meaningful reduction: salt intake fell from 9.5g per day in 2003 to around 7.6g in 2014, driven by the government's voluntary reformulation programme. Progress has since stalled and some surveys suggest a slight reversal. Men typically eat more salt than women because they eat more food overall.

Why salt raises blood pressure. The mechanism

The pathway from excess salt to cardiovascular disease is well established and operates through blood pressure.

When you consume sodium, your body maintains a careful balance between sodium and water in the bloodstream. As sodium intake increases, the kidneys retain more water to dilute it, increasing blood volume. Greater blood volume means the heart has to work harder and the blood vessels are under more pressure. Over time, this sustained elevated pressure damages artery walls, forces the heart to thicken and work harder, and dramatically increases the risk of heart attack, stroke, and heart failure.

This is a dose-response relationship: more sodium means higher blood pressure, and the effect applies to people whether or not they are already hypertensive. Multiple meta-analyses and randomised controlled trials have confirmed this dose-response consistently.

The numbers

A comprehensive 2020 meta-analysis in the BMJ covering 133 randomised trials found that each 1g per day reduction in salt intake reduces systolic blood pressure by around 1.1 mmHg in normotensive people and 1.8 mmHg in hypertensive people. These seem like small numbers but at a population level the effects are very large.

Research by Professor Graham MacGregor and colleagues at City St George's, University of London (who have led the UK's salt reduction programme) found that reducing salt intake from 9g to 3g per day would reduce stroke risk by approximately 33% and ischaemic heart disease by 25%, preventing around 20,500 stroke deaths and 31,400 IHD deaths annually in the UK.

Salt reduction is also additive to blood pressure medication. It does not replace it, but it makes it more effective, and for people with mild hypertension it may reduce or delay the need for medication.

Health effects of excess salt beyond blood pressure

While the cardiovascular pathway through blood pressure is the primary and best-evidenced concern, excess salt is associated with several other conditions.

Kidney disease

The kidneys are the primary organ for sodium regulation. High chronic sodium intake damages the kidneys directly, independently of its effect on blood pressure, increasing proteinuria (protein in the urine, a marker of kidney damage), oxidative stress, and endothelial dysfunction. High salt intake accelerates the progression of existing kidney disease and is a risk factor for developing chronic kidney disease. A JACC State-of-the-Art Review (He and MacGregor, 2020) identified clear evidence for the association between high salt intake and kidney disease.

Stomach cancer

Salt damages the lining of the stomach and promotes the activity of Helicobacter pylori, the bacterium linked to stomach cancer. A 2024 study by researchers at MedUni Vienna found a link between salt levels in a Western diet and stomach cancer risk. The World Cancer Research Fund classifies salt, and salty and salted foods, as a probable cause of stomach cancer. The UK has seen a long-term decline in stomach cancer rates, partly attributed to the reduction in salt intake since the early twentieth century as refrigeration replaced salt preservation.

Osteoporosis

High salt intake causes the kidneys to excrete more calcium in urine. As blood calcium falls, the body draws calcium from bones to compensate. Studies have shown a direct relationship between sodium excretion and calcium excretion, and a correlation between high salt intake and hip bone density loss in post-menopausal women. Reducing salt intake has been shown to produce a positive calcium balance (less calcium is lost) which may slow age-related bone loss.

Kidney stones

The increased urinary calcium excretion caused by high salt intake also raises the concentration of calcium in urine, increasing the risk of calcium oxalate kidney stones, the most common type of kidney stone.

Fluid retention and oedema

Excess sodium causes the body to retain fluid, leading to swelling (oedema) particularly in the ankles, feet, and legs. This is uncomfortable and can worsen conditions including heart failure and pre-eclampsia during pregnancy.

Emerging evidence: dementia

A JACC review (2020) notes emerging evidence for an association between high salt intake and dementia risk, potentially through blood pressure effects on cerebral vasculature and direct effects on the brain's glymphatic system. This area of research is developing and not yet as firmly established as the cardiovascular and renal links.

Where does UK salt come from? The hidden sources

The most important and most surprising fact about salt in the UK diet is how little of it comes from what people put on their food themselves.

Around 75% of salt is already in food when we buy it. It is added during manufacturing as a flavour enhancer, preservative, and texture agent. Reducing what you sprinkle on your dinner makes only a marginal difference if you continue to eat the same processed foods.

Notes on the biggest contributors

• Bread. A typical two-slice serving of supermarket bread contains around 1g of salt. Two rounds of sandwiches therefore contributes about the entire daily salt intake of a 7 to 10 year-old child. Salt in bread serves as a dough conditioner and flavour enhancer; it has been one of the most resistant categories to reformulation.
• Cheese. Cheddar typically contains 1.5 to 1.8g of salt per 100g. Salt is essential to the maturation process, making cheese hard to reformulate.
• Processed and cured meats. Bacon, ham, salami, sausages. Bacon can contain 3 to 5g of salt per 100g.
• Ready meals. Often 2 to 3g of salt per serving, sometimes more. Action on Salt has found that over half of ready meals surveyed carry a red traffic light for salt.
• Soup. A typical 400ml tin of tomato soup may contain 2 to 3g of salt. Half the adult daily allowance in one bowl.
• Breakfast cereals. A 40g serving of some branded cornflakes contains around 0.6 to 1g of salt. This surprises most people because cereals do not taste salty.
• Sauces and condiments. Soy sauce is around 8g of salt per 100ml. One tablespoon contains around 2g of salt. Stock cubes, gravy granules, ketchup, and pasta sauces all contribute meaningfully when used liberally or daily.

For the broader pattern of why so much UK food is heavily salted in the first place, see the article on ultra-processed foods.

The UK salt reduction programme. What worked, and what stalled

The UK's salt reduction programme, which began in 2003, is considered one of the most successful population nutrition interventions in the country's history. It operates primarily through voluntary targets set for food manufacturers and retailers, with 108 category-specific targets covering the grocery and out-of-home sectors.

What was achieved

Between 2003 and 2011, population salt intake fell from approximately 9.5g to 7.6g per day, a reduction of around 15%. Over the same period, average blood pressure fell by 3.0/1.4 mmHg, contributing to an estimated 42% reduction in stroke mortality and 40% reduction in ischaemic heart disease mortality in England, as measured by researchers at City St George's, University of London. This was one of the most significant public health successes of the early 2000s.

However, progress slowed and partially reversed after 2011, as the campaigning element of the programme diminished. By 2018, average intake had risen back to approximately 8.4g per day.

The 2024 targets

The government's most recent targets were set for 2024. An Oxford University/NIHR modelling study published in January 2026 estimated that if those 2024 targets had been fully met by the food industry, average adult salt intake would have dropped from 6.1g to 4.9g per day, a 17.5% reduction. Over 20 years this would prevent approximately:

• 103,000 cases of ischaemic heart disease
• 25,000 strokes
• 243,000 quality-adjusted life years saved
• £1 billion net saving to the NHS

Crucially, this would happen without any change in consumer behaviour. Purely through reformulation of processed foods. The targets are voluntary, however, and there is no mechanism to enforce or verify compliance by manufacturers.

The "healthy salt" myth. Sea salt, pink salt, and the rest

One of the most persistent misconceptions in popular nutrition is the belief that sea salt, pink Himalayan salt, fleur de sel, or other artisan salts are meaningfully healthier than ordinary table salt.

The same logic applies to "reduced sodium" salt substitutes. Some salt substitutes replace part of the sodium chloride with potassium chloride, which does not raise blood pressure and is associated with modest blood pressure reduction in its own right. These can be a useful tool for people managing hypertension. But they are not suitable for everyone. People with kidney disease or those taking certain medications (ACE inhibitors, potassium-sparing diuretics) should consult a GP before using potassium-based salt substitutes, as they can cause dangerously elevated potassium levels.

Practical steps to reduce salt intake

The most effective way to reduce salt intake is to eat fewer ultra-processed and packaged foods, because that is where 75% of the salt is. But there are practical steps within that principle.

1. Check the label and choose lower-salt options

When comparing similar products, the back-of-pack nutrition table shows salt per 100g. The traffic light system on the front of pack marks salt as:

For bread, aim for products closer to 0.8 to 1g of salt per 100g. For ready meals, look for under 1g of salt per 100g. For soups, choose varieties under 0.5g per 100g where possible. The full label-reading guide is at how to read food labels.

2. Focus on the biggest contributors first

Bread, cheese, and processed meats are the three most significant sources for most UK adults. Choosing lower-salt bread, moderating cheese portions, and replacing bacon and cured meats with unprocessed alternatives (plain chicken, eggs, fish) makes a larger difference than almost any other single change.

3. Cook from scratch more often

Home-cooked food from whole ingredients contains the salt you add yourself, which you can reduce or control. A home-made tomato sauce from tinned tomatoes contains only the salt you choose to add. The jarred equivalent may contain 2 to 5g of salt per serving before you open the lid.

4. Use herbs, spices, lemon, and vinegar instead of salt

The perception that lower-salt food is bland is partly about habit. Taste buds adapt to lower salt levels over a few weeks, and food seasoned with garlic, ginger, chilli, lemon zest, fresh herbs, or acid (vinegar, citrus) is flavourful without needing as much salt. The adaptation takes time; reducing salt gradually is more sustainable than cutting it suddenly.

5. Watch the "invisible" salty foods

Breakfast cereal, bread, soup, and ready meals are the categories where people are most surprised by the salt content. Making a habit of checking these (rather than obvious foods like crisps) closes the gap between perceived and actual intake.

6. Limit takeaways and restaurant meals

The out-of-home sector has been the most resistant to salt reduction. A typical takeaway meal can contain the equivalent of the entire daily adult salt limit, or more, in a single dish. Eating out occasionally rather than regularly, and asking for sauces and dressings on the side, helps manage this.

7. Swap tinned foods in brine for water or oil versions

Tinned fish and tinned pulses are often available in brine (high salt) or water/oil (much lower). The nutrition and practicality are otherwise identical. This is an easy swap.

8. Do not add salt at the table before tasting

An obvious step, but a meaningful one for people who salt food habitually before eating. Tasting first and adding only what is needed (if anything) typically reduces table salt additions significantly over time.

Salt and specific health conditions

High blood pressure (hypertension)

If you have been diagnosed with hypertension, reducing salt intake is one of the most evidence-based lifestyle changes you can make. The effect is additive to blood pressure medication. Aiming for closer to the WHO's 5g per day target, rather than the NHS 6g limit, is likely to produce a greater blood pressure benefit. Your GP or a registered dietitian can advise on a specific target for your circumstances.

Kidney disease

If you have chronic kidney disease (CKD), your kidneys are already less able to excrete sodium efficiently. Excess sodium accelerates kidney damage and raises blood pressure further. A low-sodium diet is typically recommended as part of CKD management. Speak to your healthcare team about specific targets, as these vary with the stage of kidney disease.

Heart failure

People with heart failure are typically advised to restrict fluid and sodium intake more strictly than the general population, as excess sodium leads to fluid retention that worsens symptoms. Your cardiology team will advise on appropriate targets.

Pregnancy

Routine salt restriction is not recommended in uncomplicated pregnancies. For women with pre-eclampsia or gestational hypertension, specific dietary advice should come from obstetric care teams rather than general guidelines.

Key statistics at a glance