These are the surprising symptoms linked to eating too much salt as research suggests high levels can cause a string of serious conditions

Description

FOR over 20 years, we’ve been bombarded with public health messages to reduce our salt intake in order to slash the UK death toll from heart disease.

The government’s Scientific Advisory Committee on Nutrition first issued the advice in 2003, when the evidence that excess salt consumption could lead to dangerously high blood pressure became overwhelming.

The goal, experts declared, should be for everyone to eat no more than six grammes of salt a day – little more than a teaspoonful – both from foods that already contain it and from salt added at the table.

But according to the British Heart Foundation, it’s a target most of us repeatedly miss.

It estimates that most adults in the UK still eat around 8.4g of salt daily – 40 per cent above the maximum target set two decades ago.

The NHS website says this is mainly because some three quarters of all the salt we consume comes from packaged and processed everyday foods – such as bread, breakfast cereals and fast-foods. In other words, it’s extremely difficult to avoid.

But now there may be added impetus to the salt reduction drive, following the publication of a series of studies in recent months linking high intake with depression, hearing loss and even dementia.

‘There has been a spate of studies linking excess salt intake with poor mental health,’ says Matthew Bailey, professor of renal physiology at the University of Edinburgh, who has carried out animal research showing salty diets trigger a surge in levels of stress hormones that can affect mood – a finding he believes could also apply to humans.

‘These studies show high salt intake over long periods of time is not just raising the risk of cardiovascular disease but possibly also mental health problems and even dementia.’

Salt – or more specifically sodium chloride – is vital for the body’s essential functions, such as keeping nerves healthy so they can send signals to tissues and vital organs, helping muscles contract properly and aiding digestion.

Humans often crave it because, says Professor Bailey, our ancestors constantly had to seek out natural deposits – which were usually spread far and wide – in order to survive. That evolutionary desire remains, even though salt is now in plentiful supply.

And when we eat too much, the kidneys detect that there are high levels of salt circulating in the blood.

They then pull water out of other tissues and organs to pump into the bloodstream to keep salt levels balanced.

The extra volume puts pressure on artery walls – making them stiffer and narrower – while also making the heart work harder to push it round the body.

Over time, this increases the risk of heart attacks, strokes and heart failure – where heart muscle effectively wears out from all the hard work.

But while the link with heart disease is well-established, salt’s potential influence on mental health and the brain is only just being uncovered.

In July, a team of researchers from Wenzhou Medical University in China published a study in the Journal of Affective Disorders which looked at more than 270,000 British people who had signed up to UK Biobank – a huge UK health and DNA database.

Researchers tracked salt intake and the number of people diagnosed with depression or anxiety over a 14-year period.

The results showed those who said they ‘sometimes’ added salt to their food were 20 per cent more likely to have a diagnosis of depression than those who never sprinkled it on their meals; those who admitted ‘always’ adding salt were 45 per cent more likely to be depressed.

And the results were not simply a one-off.

A very similar study – again involving UK Biobank participants and also published in the Journal of Affective Disorders in July – reached a similar conclusion.

Researchers from Huazhong University of Science and Technology, in Wuhan, China, this time tracked 439,000 people over 12 years and found those who always added salt were 37 per cent more at risk of depression – and 27 per cent more likely to have anxiety.

‘We know from studies that animal behaviour changes when you switch them from a no or low salt diet to a high salt diet,’ says Professor Bailey.

In 2022, he and fellow researchers from Edinburgh University published a study in the journal Cardiovascular Research which showed levels of stress hormones, such as cortisol and noradrenaline, in mice soared by 75 per cent when they were put on a salty diet.

‘Eating too much salt damages our heart, blood vessels and kidneys but our study showed it may also change the way the brain handles stress,’ Professor Bailey said.

But how would the popular household condiment have such a dramatic impact on mood?

One theory is that it drives up production of interleukin-17A (IL-17A), an inflammatory protein which is already known to play a part in pushing up blood pressure.

In the brain, excess IL-17A activates inflammatory pathways and disrupts the normal balance of neurotransmitter chemicals that controls mood.

Earlier this year, in the Journal of Immunology, researchers at Nanjing Medical University in China reported the results of a study on mice which showed levels of IL-17A in the spleen, blood and brain jumped when they were fed a salty diet – as did signs of stress and low mood.

Yet when salt was fed to mice genetically bred to not produce IL-17A, there was no increase in depression-like symptoms – such as being less interested in exploring new spaces.

Scientists think it’s this interaction between salty diets and the mood-changing protein IL-17A that might explain why eating too much may harm mental health. They now hope to carry out human studies to see if reducing salt intake also prevents this increase in protein levels and the onset of depression.

But is our craving for salt doing even more severe harm to our health?

Two recent studies have also found those who add it to food are more at risk of dementia – one, by experts at Qingdao University in China, published last week (SUBS; OCT) in the Journal of Affective Disorders found it increased the chance of developing the condition by 19 per cent; the other, in Brain and Behaviour in 2024, put it as high as 73 per cent.

Exactly how is not yet clear but high blood pressure is one of the main contributors to  vascular dementia – which affects around 180,000 people in the UK.

And another study in the Journal of Nutrition, Health and Ageing in October 2025, by researchers from Kyungpook National University Hospital in South Korea,  showed adding salt to meals may even heighten the risk of hearing loss by 23 per cent – possibly by disrupting the normal balance of fluid in the inner ear, which is vital for good hearing.

But cutting back on salt intake is no easy task, Professor Bailey told Good Health.

He says: ‘I never add it to my food and yet urine tests suggest I’m still averaging about 8g a day – that shows just how difficult it is to stay within the guidelines.’