Salt is a threat to the nation's health - but the Government cannot dictate what we eat

The row that has broken out between the Department of Health and some of Britain's largest supermarket chains at least serves to thrust into the spotlight one of the greatest destroyers of the nation's health: salt. Too much of it raises the body's blood pressure, which often leads to strokes and heart disease. And most of us consume too much at the moment. Researchers from St George's Hospital in London have estimated that if we significantly reduced our intake the number of people falling victim to strokes each year would fall by a third, and the numbers suffering from heart disease by a quarter. If Britain modified its eating habits, thousands of lives would be saved.

Melanie Johnson, the Public Health Minister, is therefore quite right to identify the public's intake of salt as something that falls within her remit. And the national campaign launched today to persuade consumers to lower their intake of salt - with the slogan "Too much salt is bad for your heart" - is the sort of thing a public health minister ought to be doing. Campaigns to raise awareness of health and safety issues are usually done well by British governments.

Ms Johnson is also quite right to look to Britain's supermarket chains as vital partners in her efforts. Around 80 per cent of the public's salt intake comes from the processed foods sold by supermarkets, particularly their "own label" ranges. They have considerable power to make the nation's diet healthier. And supermarkets have largely woken up to that fact. Most have devised plans to reduce the amount of salt in their products. But what should have been a happy partnership with the Government, with everyone working towards a common goal, has fallen apart.

The dispute centres on a letter Ms Johnson sent to the some of the largest supermarket chains - Sainsbury's, Waitrose, Iceland and Asda - requesting detailed information on their plans to reduce the salt content of their products, and giving them a deadline later this month to respond. The supermarkets have decided to ignore the Department of Health's demands, arguing that they have already submitted detailed plans, agreed with the Food Standards Agency, for reducing salt levels in their foods. They believe they are doing enough, and warn that it will be far from easy to wean the British public off its high-salt diet.

Supermarkets and food manufacturers put salt in food for flavour. Without added salt, many of their processed foods, such as frozen pizzas, baked beans and spaghetti hoops, would be bland and, as a result, customers would not buy them. Although they can undoubtedly do more to utilise substitute flavourings, the bafflement of supermarkets when faced with arbitrary targets handed down by an impatient Government is understandable. Ministers cannot expect to run the private sector in addition to the public one.

This spat highlights the broader tensions in society between the public's desire for cheap food, and growing fears regarding the nation's health. It also raises the question of whether it is right for governments to attempt to control what people eat. It is certainly true that while food is cheap, the treatment is not - according to the Commons Health Select Committee, Britain's obesity crisis costs the NHS some £3.5bn a year. Nevertheless, the Department of Health's role is to make people aware of the need for a healthy diet and give them advice on how to achieve one. It can even go as far as ensuring that supermarkets implement honest food labelling. But is dictating every last ingredient really a legitimate function of the state?

Eating healthily is a personal (and parental) responsibility. The Government should devote its energies to raising public awareness of the dangers of a poor diet, and to encouraging good eating habits and regular exercise in schools. The Department of Health cannot dictate what people can and cannot eat. Even if this were a desirable approach, life simply does not work like that. Unless the Government accepts this, it will end up leaving a bad taste in the public's mouth.