The analysis of blood pressure and heart disease data from 2003 through to 2011 suggests efforts to reduce population salt intake in the UK led to a fall in population blood pressure and deaths from stroke and heart disease – preventing approximately 18,000 stroke and heart attack events a year, 9,000 of which would have been fatal.
Writing in the British Medical Journal (BMJ), researchers from the Wolfson Institute of Preventive Medicine at Queen Mary University of London, UK, analysed whether the reductions in population salt intake that were seen in England between 2003 and 2011 were associated with any effects on blood pressure (BP) and mortality from stroke and ischaemic heart disease (IHD).
“Our analyses showed that the average BP in the adult population in England decreased by 3/1.4 mm Hg from 2003 to 2011,” wrote the research team – led by Dr Feng J He. “This could be attributable to various factors such as the reduction in salt intake, the increase in fruit and vegetable consumption, and the improvement in BP treatment and control.”
However, he added that after taking in to account potential confounders including BP treatment, age, sex, alcohol consumption and fruit and vegetable intake, the findings still suggest that a reduction in population salt intake “is likely to be an important contributor to the falls in BP.”
Sonia Pombo, a co-author of the study commented that the findings show how effective salt reduction policies can be: “The food industry has worked hard to reduce levels of salt across many of their products, and as a result, average intakes of salt have gone down.”
“The brilliance of the programme means that shoppers can still buy their favourite foods, just with less salt in them,” she said.
Salt reduction saves lives
The team used BP and other CVD risk factor data from the Health Survey for England, which is an annual survey of a random sample of the English population living in private households. Data from more than 30,000 people was analysed, with He and his colleagues using Health Survey for England data for 2003, 2006, 2008 and 2011.
“From 2003 to 2011, there was a decrease in mortality from stroke by 42% and IHD by 40%,” reported the team. “In parallel, there was a fall in BP of 3.0±0.33/1.4±0.20 mm Hg, a decrease of 0.4±0.02 mmol/L in cholesterol, a reduction in smoking prevalence from 19% to 14%, an increase in fruit and vegetable consumption portion/day, and an increase in body mass index.”
Salt intake, as measured by 24 h urinary sodium, was also seen to decrease by 1.4 g/day, they noted.
“It is likely that all of these factors (with the exception of BMI), along with improvements in the treatments of BP, cholesterol and cardiovascular disease, contributed to the falls in stroke and IHD mortality,” wrote the authors.
Although salt intake was not measured in the participants of the survey, He and colleagues noted that the fact that the average salt intake in a random sample of the population fell by 15% during the same period suggests the reduction in BP “would be largely attributable to the reduction in salt intake rather than antihypertensive medications.”
Further action needed?
While the findings suggest that existing reeductions in salt intake have already saved lives, the authors noted, however, that UK salt intake remains high - at 8.1g/day - and is above the WHO target of 6g/day.
“It is vital that we continue to get the maximum reduction of salt from the food industry,” said Professor Graham MacGregor, chairman of Consensus Action on Salt & Health (CASH), and senior author of the new data.
“The Department of Health must take a much more robust attitude to the food industry, forcing them to reduce salt intake quicker and across the board in order to assure a level playing field. If they do not, we must regulate the salt targets to ensure that the maximum number of lives are saved and the maximum cost savings are made.”
Global implications
The authors said the results have important implications to the rest of the world, given that nearly every country now eats between 9 and 14 grams of salt a day.
A CASH statement said that the UK has ‘led the world’ with a well thought out, structured salt reduction programme – and called for other countries to follow.
CASH noted that well-known international branded companies – including Unilever, Nestlé, Kraft, Kellogg’s, Heinz, Pepsi-Co - have reduced salt a great extent in the UK, and suggested that ‘if they can reduce it without loss of sales in the UK they can do so internationally.’
“In our view it would now be a gross breach of ethical and corporate responsibility for companies not to reduce salt as the benefits of salt reduction are now so clear,” commented Clare Farrand, programme lead for World Action on Salt & Health (WASH).