- Hattie E Burt, researcher,
- Mhairi K Brown, researcher,
- Feng J He, professor,
- Graham A MacGregor, professor
- Wolfson Institute of Population Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
- Correspondence to: H Burt
Strong evidence shows that excess salt intake is linked to multiple non-communicable diseases, including a dose-response relationship with blood pressure and cardiovascular disease,1 the leading cause of death and disability worldwide. And in May 2022, 70 health and scientific organisations, including the World Hypertension League and the International Society of Hypertension, called for “all health care professionals, scientists, and the organisations that represent them to advocate for sodium [salt] reduction to be a high global priority and for all nations to develop effective programs to reduce sodium intake to recommended levels.”2
Individuals can take steps to reduce their salt intake by adding less salt to food and by choosing to consume fewer highly salted foods. However, with around 75% of salt coming from packaged and prepared foods,3 many of which we rely on as affordable and convenient staples, individuals are fighting a losing battle. Action to reduce salt intake across the whole population—for example, through policies that incentivise food manufacturers to reformulate products with less salt—is therefore required.
The UK led the world with its 2003 voluntary salt reduction strategy and saw salt intakes and cardiovascular deaths fall.4 But the most recent national measurements show average salt intake has drifted up.5 The latest public health policies have focused on sugar and calorie reduction and have not included strong enough incentives to reduce salt levels further. Stronger action is needed to reduce the risk of cardiovascular disease and associated costs for health services and society.
Evidence for salt reduction
Some controversy has surrounded the importance of reducing salt intake for preventing non-communicable diseases. Most of this is based on a few prospective cohort studies suggesting a J or U shaped association between salt intake and cardiovascular events—that is, both lower (<7.5 g/day) and higher (>15 g/day) salt intakes were associated with increased risk of disease. However, the US National Academies of Sciences, Engineering, and Medicine and others describe methodological limitations (such as inaccurate estimates of individual salt intakes from single spot urine samples) and point to a high risk of bias in these cohort studies, alongside researcher conflicts of interest.67
These studies continue to be used to support the food and beverage industry’s vested interests in the use of excessive amounts of salt to preserve food, enhance taste, and increase thirst,6 but the totality of evidence shows that the relationship between salt intake and blood pressure is one of the most robust causal associations we know.8 The causal association between blood pressure and cardiovascular disease is similarly robust.9 Consequently, the World Health Organization and nearly all national governments, including the UK, recommend a maximum intake of 5-6 g of salt a day.10 WHO lists policies to encourage reformulation of salty food products as one of its “best buys” for preventing chronic disease.11
The UK’s voluntary salt reduction programme, with comprehensive targets for products that have salt added during manufacturing such as bread, ready meals, and breakfast cereals, shows what can be achieved. Target salt contents covering more than 80 food categories were published in 2006 and closely managed by the Food Standards Agency (FSA) until 2011. During that period, salt levels in many foods decreased by 20% to 40%, leading to an important fall in population salt intake from 9.5 g/day to 8.1 g/day between 2003 and 2011.4 Average blood pressure in England also fell during this period, as did deaths from cardiovascular disease; the reduction in salt intake was likely to have been an important contributor.4 In fact, according to data from the National Institute for Health and Care Excellence, reducing salt intake by 1.4 g/day from 2003 to 2011 is estimated to have prevented around 9000 cardiovascular deaths a year and saved the UK economy £1.5bn annually.1213 The UK’s pioneering policy of reducing population salt intake by setting salt reduction targets for a comprehensive range of products has since been widely replicated, with 57 countries having implemented salt targets, a third of which are mandatory.14
Salt slips from public health focus
Despite the initial success, progress on salt reduction in the UK stalled when responsibility for nutrition was transferred from the Food Standards Agency to the Department of Health in 2011. Power was handed back to the food industry through a self-regulation framework called the public health responsibility deal, whereby the food industry made voluntary pledges to improve the nutritional quality of its products, but took little action. The committee overseeing the responsibility deal was dominated by food industry representatives, reporting mechanisms were relaxed and lacked transparency, and new salt targets—which should have been set in 2011 to be achieved by 2014—were not set until 2014, to be achieved by 2017.15After a change of political leadership, the public health responsibility deal was dissolved and responsibility for nutrition, including salt, was eventually handed to Public Health England (PHE), and then back to the Department of Health when PHE was abolished in 2020.
These frequent changes in governance are a key reason why the good progress seen in the early days of the voluntary salt reduction programme has not been sustained.15 Average salt intakes in the most recent study in 2018-19 had risen to 8.4 g/day, 40% higher than the government’s recommended 6 g/day maximum.5 Almost half of the 2017 average salt targets were not met, meaning that food products available for purchase have unacceptably high levels of salt, despite several targets for products such as bacon, ham, and sausages, not being made more stringent since 2009.5
Voluntary targets rely on strong checks and balances to hold food companies to account, but with responsibility for salt reduction being passed around like a hot potato, and government outlining no penalties for non-compliance, monitoring and enforcement have been compromised.16 Because the short term health effects of salt on blood pressure are often asymptomatic and do not usually manifest as cardiovascular disease until later in life, salt reduction is not necessarily a priority for policy makers or the public. For example, a 2021 survey among 6271 adults from 4338 households across England, Wales, and Northern Ireland, found that for the 20% of respondents who were concerned about the food they eat, the amount of sugar in foods was the leading food related concern (63%), with salt coming fifth at 54%.17 What’s more, the government’s current focus is on reducing obesity through sugar and calorie reduction programmes, and recent policies provide food companies with little impetus to reduce salt levels.
One such policy that fails comprehensively to target high salt products is the restrictions on advertising unhealthy food to children. The policy includes a 9 pm TV watershed and a total online ban for certain foods high in fat, salt, and sugar, but high salt products are included only if they fall in the scope of sugar and calorie reduction programmes and the soft drinks industry levy, leaving many key contributors to salt intake exempt (table 1).18 This policy is currently going through the UK’s legislative process and so is vulnerable to lobbying to weaken it. Implementation has already been delayed from January 2023 until January 2024.19
In October 2022, the government is also set to bring in restrictions for large retailers on the placement of high fat, salt, and sugar products in high footfall areas such as retail checkouts. Corresponding restrictions on price promotions, including multibuy deals, are part of the same legislation but may also be delayed a year. These measures will also omit the same high salt products as the advertising restrictions. Only half of the 40 food categories with salt reduction targets are included in the advertising restrictions and just nine in the price and place promotion restrictions (table 1).
Calorie labelling in the out-of-home sector was implemented in April 2022, with large restaurant, cafe, and takeaway businesses now required to display calorie information. While this policy encourages businesses to re-evaluate their menu options and reformulate dishes, the continued absence of salt labelling is reflected in the high salt content of foods sold in these settings. By contrast, large retailers have adopted voluntary “traffic light” front of package labelling that warns consumers of high salt content (>1.5 g/100 g or >1.8 g/portion), thereby incentivising the food industry to reformulate supermarket products with less salt. In 2018, Action on Salt surveyed lunchtime salads available in supermarkets, restaurants, and fast food chains, finding that salads from restaurants and fast food chains contained 75% more salt than those purchased from supermarkets (fig 1).20 In an earlier study examining the salt content of pizzas sold in the two sectors, takeaway pizzas contained 213% more salt than equivalent supermarket pizzas (fig 1).21 Clearly, in the absence of salt labelling, the out-of-home sector has little incentive to keep salt content in check.
Policy makers need to act now
Reducing population salt intake is relatively easy for manufacturers. Lowering salt levels in food products does not affect their weight or volume, and there are few technical barriers. For the small minority of products in which salt has a technical function, large variations in the salt content of similar products show how much salt can still be innocuously removed.22 Moreover, if salt is gradually and consistently reduced across the food chain, consumers do not perceive any change in taste, meaning they continue to buy and enjoy the same products, but with less salt.1323 Thus, the challenge is less about maintaining consumer satisfaction and more a political choice regarding salt regulation.
Manufacturers are reluctant to act alone because they fear losing market share.24 Comprehensive, regulated salt reduction targets, with penalties for non-compliance, are therefore needed to hold all food and beverage companies to the same rules. The UK’s voluntary sugar reduction targets have also seen disappointing progress,25 reinforcing the need for industry regulation. Indeed, chief executives of the UK’s major food retailers have stated that they cannot act without legislation to ensure all competitors are making similar investments.24
Evidence showing the effectiveness of mandatory salt reduction targets continues to grow. In response to a 2013 law in Argentina regulating salt content in processed foods, compliance with the targets reached 90%26 and average salt intake fell by 18% from 11.2 g/day in 2011 to 9.2 g/day in 2015.14 South Africa also introduced mandatory maximum salt limits in processed food in 2016, and early results point to a drop in average salt intake by 1.2 g/day over a 4.6 year follow-up, with larger reductions in black adults and those from low socioeconomic groups, who are at high risk of hypertension and cardiovascular disease.27 In addition to ensuring that salt is included in the latest food marketing regulations, the UK government must enact mandatory salt targets rather than persisting with voluntary targets that are not met.
While a population-wide “upstream” policy of mandatory targets can achieve reductions in salt intake on its own, international experience shows that greater reductions in salt consumption are achieved when a combination of measures is implemented as part of a comprehensive salt reduction strategy.28 Front-of-pack nutritional labelling can also incentivise food manufacturers to reformulate their products with less salt, sugar, and saturated fat to achieve a visibly healthier label. Finland pioneered this strategy in the early 1990s when it implemented salt labelling regulations, including highly effective “high salt” warning labels. Reductions in salt content of key dietary contributors, including bread and sausages, were followed by corresponding reductions in population salt intake, blood pressure, and deaths from stroke and heart disease.29 However, because front-of-pack labelling is voluntary in the UK, one in four products still do not display the UK’s recommended traffic light label, first introduced nine years ago.30 A legislative approach is clearly needed; in 2020, government consulted on the UK’s approach to labelling but the results are yet to be released.
Fiscal measures, such as excise duties, are another potentially powerful policy tool that has thus far been ignored in the UK as a way to tackle high salt intake. The soft drinks industry levy shows how effective properly targeted fiscal measures can be: between 2015 and 2019 there was a 43.7% reduction in total sugar content of drinks subject to the levy, while overall sales of these drinks increased by 14.9%.25 Taxes have been criticised for being regressive, but as the levy shows, if they are used to drive reformulation, companies can respond by removing excess salt from their products to avoid paying extra tax. The national food strategy proposed a £6/kg salt reformulation tax to incentivise food manufacturers to reduce salt in their products, which could potentially reduce salt intake by 0.2-0.6 g/day per person.24
Salt reduction has a key role in improving healthy life expectancy and reducing health inequalities in the UK by 2030—key parts of the government’s levelling up agenda31—as people on low incomes are at the greatest risk of cardiovascular disease.
In a bid to drive salt reduction, WHO published global benchmarks for salt levels in over 60 food categories in 2021,32 many of which are more ambitious than the UK’s current salt targets. Countries are being asked to step up their efforts to reduce population salt intake by 30% by 2025—a goal the UK currently is far from meeting. However, by implementing evidence based regulatory measures, government can save thousands of people from unnecessary ill health and deaths from stroke and heart disease, while saving the economy billions of pounds in healthcare and lost productivity costs.
Salt intake is a major underlying cause of raised blood pressure, the leading cause of death and disability from stroke and heart disease
In the UK, most salt comes from processed foods, and reducing intake requires food manufacturers to reformulate their products
Current voluntary salt targets and recent public health policies are not strong or comprehensive enough to incentivise manufacturers to act
Mandatory targets and labelling, alongside tougher advertising and promotion restrictions, are needed
Contributors and sources: All authors have research interests in nutrition and global health, particularly on reducing dietary salt, sugar, and saturated fat intake at the population level to prevent non-communicable diseases. MKB and HEB conceptualised the article. All authors contributed to drafting the manuscript and approved the final version. FJH is the guarantor.
Competing interests: We have read and understood BMJ policy on declaration of interests and declare that GAM is the chair of Blood Pressure UK and Consensus Action on Salt, Sugar and Health (CASSH). FJH is a member of CASSH. Neither receive any financial support from these organisations.
Provenance and peer review: Not commissioned; externally peer reviewed.