Be salt aware: it’s still an important issue!
Mhairi Brown, Nutritionist, Action on Salt
The ancient practice of adding salt to food was primarily done for preservation and safety purposes in times when access to good quality fresh produce was sparse, and over its habitual use, we have acquired a salty preference. Through refrigeration we now no longer need salt for preserving our food, but the liking for a salty taste has now stuck for many of us, and may be difficult for some of us to ‘kick the habit’. Difficult, but not impossible.
Sodium, a mineral found in salt (sodium chloride), is needed for nerve and muscle function, and helps regulate the amount of fluid in our cells. However, we only need a small amount of salt and it is very easy to exceed these requirements. In fact, as a nation, we are currently consuming a third more than the recommended maximum - 8g per day on average according to Public Health England. Excess salt intake can cause our bodies to retain more fluid, which causes our blood pressure to rise. Over time, raised blood pressure increases the risk of developing heart disease or stroke, the two biggest causes of death and ill health worldwide. Excess salt intake has also been shown to increase risk of stomach cancer.
What about the ‘Salt Controversy’?
Despite decades of high quality research demonstrating that too much salt is bad for our health, some studies have recently suggested that salt may only play a harmful role when intake is very high (> 12.5g/day) or very low (<5g). The authors of these studies therefore conclude that current intakes are mostly within the healthy range. However, a recent study led by Professor He from Queen Mary University of London, in collaboration with researchers from the University of Calgary, Harvard TH Chan School of Public Health, US CDC and the Brigham and Women’s Hospital found that inaccurate measurement of salt intake could be an important contributor to these findings, and a major study limitation. The gold standard method of measuring salt intake is by measuring sodium levels in all urine passed in a 24-hour period, and ideally over multiple days, as our salt intake varies from day to day, depending on the foods we eat. These controversial studies measured levels in just one spot-sample of urine, and then use a formula called the Kawasaki formula to estimate daily salt intake from the sodium present in the spot-sample. This leads to bias. When accurate measurements are used, a direct linear relationship between salt intake and death is found down to an intake of 3g salt per day.
UK Salt Reduction Programme
The Scientific Advisory Committee on Nutrition (SACN) issued recommendations on salt in 2003, stating that average daily salt intake should be no more than 6g per day – equivalent to a teaspoon. Yet we are still eating too much salt. The issue may be that much of the salt in our diet is already present in everyday foods, and not necessarily added by the individual. This includes bread and processed meat, as well as food eaten out in restaurants.
Work on salt reduction in the UK began in the early 2000’s and has involved a collaborative effort from government, the food industry and NGO’s. A key strategy set out by government bodies for the food industry involved reformulation, which is the process of gradually reducing the amount of salt added to processed food. This has proven to be an effective strategy in reducing the nation’s salt intake, as it allows consumers to continue buying the same products with less salt. It does not discriminate against different social groups, and requires minimal changes to consumer behaviour and dietary habits. As a result of this strategy, the average UK population salt intake fell from 9.5g to 8.1g per day between 2003 and 2011.
Over the years, we have seen progress from the food industry in lowering salt levels in their products – for example, the average salt content of packaged bread fell from 1.23g per 100g in 2001 to 0.98g per 100g in 2011 - but concern has been expressed that with the more recent focus on sugars and calories, progress towards lowering salt may have slowed. Public Health England’s comprehensive analysis of progress made towards the voluntary 2017 salt targets, published in 2018, highlighted that retailers met 73% of average targets, compared to manufacturers who met just 37%. PHE also found that products available in the out-of-home sector were generally higher in salt than comparable products available in supermarkets.
If we could lower our intake of salt to the recommended limit of 6g a day, the Department of Health and Social Care estimates that 8,000 premature deaths from strokes and heart disease could be prevented each year. The National Institute for Health and Care Excellence also estimate that this reduction in salt intake could save £3 billion a year in healthcare costs – a win for our health, and our NHS!
Mhairi Brown is a nutritionist who works on salt reduction projects within the team at Action on Salt.
See the blog on the British Nutrition Foundation website here