Eating a diet high in salt significantly increases the risk of heart failure, scientists have warned after a major 12-year study.
Speaking ahead of a presentation to the European Society of Cardiology in Barcelona, Professor Pekka Jousilahti of Finland’s National Institute for Health and Welfare, put it simply: “The heart does not like salt.”
According to the World Health Organisation, an estimated 2.5 million deaths a year could be prevented if people reduced their consumption of salt to its recommended level of 5g.
Most people eat well in excess of this, anything from 80 to 140 per cent more than they should, according to the WHO.
Prof Jousilahti said their study found that eating more than 13.7g a day of sodium chloride doubled the rate of heart failure.
“High salt intake markedly increases the risk of heart failure,” he said.
“This salt-related increase in heart failure risk was independent of blood pressure.
“People who consumed more than 13.7g of salt daily had a two times higher risk of heart failure compared to those consuming less than 6.8g.”
Experts are divided on how much salt people can or should eat. The NHS, for example, recommends no more than 6g a day, slightly above the WHO limit.
Prof Jousilahti said optimal daily salt intake was “probably even lower than 6.8g”, the lowest level they used in their study.
While humans do need salt, he said the physiological requirement was for about 2g or 3g a day.
“Studies in larger, pooled population cohorts are needed to make more detailed estimations of the increased heart failure risk associated with consuming salt,” he added.
“High salt intake is one of the major causes of high blood pressure and an independent risk factor for coronary heart disease (CHD) and stroke,” he said.
“In addition to CHD and stroke, heart failure is one of the major cardiovascular diseases in Europe and globally but the role of high salt intake in its development is unknown.”
The study followed 4,630 women and men aged 25 to 64 in Finland over 12 years. Samples of their urine were tested to gauge their salt intake.
The researchers divided the subjects into five groups based on their salt intake; the low-salt group consumed less than 6.8g a day and the highest had more than 13.7g a day.
Over the course of the study, 121 men and women developed new heart failure.
When the results were adjusted for age, sex, study year and area, the group consuming the most salt were 2.1 times more likely to develop heart failure and the group who ate the second highest amount of salt – between 10.96g and 13.7g – were 1.7 times more likely.
According to the WHO, consuming less than 5g a day “helps to reduce blood pressure and risk of cardiovascular disease, stroke and coronary heart attack”.
“The principal benefit of lowering salt intake is a corresponding reduction in high blood pressure,” it says.
Member states of the WHO have agreed to reduce the global population’s intake of salt by 30 per cent by 2025 because of the health benefits.
The NHS’s website says food with more than 1.5g of salt (the equivalent of 0.6g of sodium) per 100g should be considered high salt, while 0.3g (0.1g sodium) per 100g is considered low.
It warns that 75 per cent of salt in our diet comes from bread, breakfast cereals and ready meals – before any salt is added at the table.
“A diet that is high in salt can cause raised blood pressure, which currently affects more than one third of adults in the UK,” it says.
“High blood pressure often has no symptoms, and it is estimated that in England about one in every three people who have high blood pressure don’t know it. But if you have it, you are more likely to develop heart disease or have a stroke.
“Cutting down on salt lowers blood pressure, which means that your risk of having a stroke or developing heart disease is reduced.”
It includes a list of foods that are usually high in salt, such as anchovies, bacon, cheese, gravy granules, olives, pickles, prawns and soy sauce.
But the NHS site also warns pasta sauces, crisps, ready-made sandwiches, sausages and ketchup can have large amounts.
Even dissolvable vitamin supplements and painkillers can contain up to a gram of salt in each tablet.
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