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Salt Reduction and CVD Deaths 'Have Both Stalled'

The Government's voluntary salt reduction programme is "no longer fit for purpose", according to health lobby group Action on Salt. The charity was commenting on a new study by its research group published in the Journal of Hypertension showing that earlier reductions in UK mean salt intake had "stalled", accompanied by a similar interruption in previously declining mortality from cardiovascular disease (CVD).

The researchers, from the Wolfson Institute of Population Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, used data from six national dietary surveys to assess mean dietary salt intake from 2003 to 2018. These involved between 449 and 1069 participants per year, all aged 19 to 64, living in England, and having measurements of 24-hour urinary sodium excretion.

They also assessed trends of blood pressure (BP) and other CVD risk factors among adults in the same age range taking part in the Health Survey for England for 6 years between 2003 and 2018 (between 2651 and 6738 participants per year). The research team estimated CVD mortality rates for each year from Global Burden of Disease statistics and mid-year population estimates from the Office for National Statistics.

Initially Successful Salt Reduction Programme "Stalled"

Analysis showed that the UK's salt reduction programme, started by the Food Standards Agency (FSA) in 2003, had been "initially successful", they said. Between 2003 and 2014, the mean population daily salt intake declined from 9.38g to 7.58g (standard deviation, SD, 4.64 and 3.41, respectively, p<0.01). However, the programme then "stalled", followed by an increase to 8.39g (SD 4.13) in 2018 (p<0.01).

In tandem, the researchers observed similar trends in BP and CVD mortality between 2003 and 2018. From 2003 to 2014, mean BP decreased from 125.3/74.48 (SD 15.92/11.33) mmHg to 122.57/73.33 (SD 14.92/10.75) mmHg (p<0.01), followed by a plateau to 2018 (mean 122.04/73.84 mmHg, SD 14.64/10.54, p>0.05). 

Likewise, reductions seen in CVD mortality between 2003 and 2014 then levelled off. Stroke initially declined from 12.24 to 8.19 cases per 100,000 (p<0.01), and ischaemic heart disease from 43.44 to 27.23 cases per 100,000 (p>0.05), then plateaued after 2014 (p>0.05).

Concomitant BP and CVD mortality reductions were also interrupted when the decline in salt consumption reversed. The researchers said that while other factors, such as changes in potassium intake from fruit and vegetable consumption, probably contributed to the BP changes, they were likely to be "at least partially attributable to the changes in population salt intake". 

Later Reduction Targets "Too Lenient"

The team noted that there had been a delay resetting salt targets in 2014 after transfer of responsibility from the FSA to the erstwhile Department of Health, 

"effectively handing power to the food industry to police themselves". Although targets had been reset in 2017, these were "too lenient", had no enforcement measures attached, and responsibility between the Department and the then extant Public Health England was not clear.

Action on Salt, which has been campaigning to reduce the population's salt intake since 1996, said: "At the height of its success (2003-2014), the UK salt reduction programme led to a 19% reduction in salt intakes and saved more than 9000 lives a year." Had it continued, further reductions in salt intake could have prevented an estimated 38,000 deaths from CVD in the subsequent four years, it stated. However, since then, the Government "handed responsibility for salt policy to food industries", resulting in "weak policies" that have "failed to reduce salt intake". 

Co-author Sonia Pombo, campaign lead for the charity, described the programme as "a shell of its former self". The ultimate impact has been "death and suffering from strokes and heart disease". A mandatory salt reduction programme was now "the only option", Action on Salt said.

The campaign group's chairman and founder Graham MacGregor, professor of cardiovascular medicine at Queen Mary University of London and co-author of the study, said that the findings reinforced "the urgent need" for worthwhile reductions in salt intake. "It is now up to the Government to set up a coherent strategy where the food industry is instructed what to do, rather than the food industry telling the Government what to do."

Asked to comment by Medscape News UK, a Government spokesperson said: "Our salt reduction programme sets firm and clear targets for all sectors of the food industry to reduce salt content in their products. Thanks to the programme, the amount of salt in food has fallen by around 20% since 2006 - helping to prevent nearly 70,000 heart attacks and strokes while reducing pressure on the NHS."

The spokesperson pointed out that product targets had been revised downwards four times since they were first set in 2006. The most recent salt reduction progress report in 2020 showed that 83% of retailer and manufacturer branded products met maximum targets and around half the average salt reduction targets.

However, in a statement, John Maingay, director of policy and influencing at the British Heart Foundation, said: "This study shows how little progress there has been in recent years to reduce the salt in our food." Most people eat too much salt, he said, raising the risk of high blood pressure and then heart disease. 

"Helping the nation to cut its salt intake would prevent more heart attacks and strokes, easing pressure on the NHS, and the Government and food industry have a critical role to play in this." The new study "should convince politicians to give food manufacturers more incentives to reduce the salt content of their products, and start seriously considering mandatory measures to follow the current voluntary programme."

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Editor's note: This article was updated on 20 September to include a comment from a Government spokesperson.