Worldwide, raised blood pressure throughout its range is the major cause of death and the second leading cause of disability after childhood malnutrition and this is through the strokes, heart attacks and heart failure it causes. More than 60% of all strokes and approximately half of all heart disease is due to raised blood pressure.
Our current high salt intake plays a major role in raising blood pressure and, particularly, the rise in blood pressure that occurs with increasing age. Evidence that relates salt intake to blood pressure comes from six different lines of evidence - epidemiology, migration, intervention, treatment, animal and genetic studies. All of these suggest that our salt intake is not only important in raising blood pressure, but a reduction in salt intake would lead to a reduction in population blood pressure, a reduction in the rise in blood pressure with age and better control of those who are already on blood pressure treatment.
The current salt intake in most countries in the world is between 10 and 20 grams/day and recommendations from the WHO set a world-wide target of reducing salt intake in all adults to less than 5 grams/day. These recommendations are similar in other countries and the UK has set much lower levels for children depending on age. In most developed countries salt consumption is passive - that is it is already added to processed, ready prepared, canteen, restaurant, fast and takeaway foods. Only 15% of salt intake is added in cooking or at the table and 5% is naturally present in foods.
The only way, therefore, that a reduction in the population's salt intake can be made in these countries is by the food industry slowly reducing the very high and unnecessary salt concentrations of all foods where salt has been added and doing this slowly over a period of time, e.g. in the UK, five years. In addition, a public campaign educating the public about the dangers of eating too much salt would lead to the use of less table and cooking salts and put additional pressure on the food industry.
The public has a right to know exactly what foods contain and, in relation to salt, it is vital that the salt content per serving is on all products with a recommended intake accompanying this. There should also be a signpost or traffic labelling system which indicates whether a product is low (green), moderate (amber) or high (red) in salt. The benefits of reducing salt intake are very large. For instance, if salt intake is reduced by 6 grams/day there would be a 24% reduction in stroke mortality and an 18% reduction in coronary heart disease mortality.
Of all public health strategies, a reduction in population salt intake is the most easy to achieve as it does not require the population to change what it eats, but does require changes from the food industry. Although this change could occur without the public necessarily being involved, it would be greatly helped by a public health campaign. The UK, for once, is leading in this area of public health but one would expect, given the evidence, that other countries, particularly Australia, should rapidly adopt this and overtake the UK in the next few years.