The connection between excessive salt consumption and cardiovascular disease and stroke has been established by a raft of scientific studies. Average consumption of salt in most Western countries is 10g a day, and the difference between highest and lowest intake levels is around 5g. The WHO advises that adults consume no more than 5g per day, but man governments consider 6g to be a realistic target.
The new meta-analysis, conducted by researchers at Warwick and Naples Universities and published in the British Medical Journal, looked at the results of 13 published prospective studies on habitual salt intake and stroke and cardiovascular disease rates in the US, Finland, Japan, The Netherlands, Scotland and Taiwan. Altogether the studies included some 170,000 people.
After taking into account differences in study design and quality, they concluded that a 5g reduction in salt intake at the population is associated with a 23 per cent difference in stroke rates, and a 17 per cent difference in total cardiovascular disease.
The researchers estimated that eating less salt could avert 1.25 million deaths from stroke and almost 3m deaths from cardiovascular disease – and these projections are seen as conservative because of imprecision in assessing salt intake.
They recognise industry efforts to reduce consumption, such as the UK Food Standards Agency’s campaign, which sets voluntary targets for industry and has succeeded in reducing population salt intake by about 10 per cent (from 9.5g to 8.6g a day) in four years.
But these results are still far from the target, and while many governments prefer the voluntary approach regulation has its advantages.
“For population salt intake to approach the recommended targets within a reasonable time-frame, an upstream approach is now necessary alongside the traditional downstream public health approach based on health promotion and behavioural changes,” they wrote.
A spokesperson for the UK’s Food and Drink Federation, the voice of the industry, said: “FDF members continue to lead the way on reformulating products to be lower in salt, providing consumers with an even greater choice of ‘better-for-you options’. Our members have put in a great deal of time, research and money into the highly complex task of changing the recipes of some of Britain’s best-loved brands, and into creating new product ranges which will appeal to customers and support their need for healthy eating choices.”
The pointed out that food product labelling schemes, such as the Guidance Daily Amount (GDA) scheme, are helping to raise awareness of salt intake amongst consumers.
Professor Graham MacGregor, chairman of Consensus Action on Salt and Health recognised that the UK is leading the way in salt reduction, but said: "It is vital that manufacturers and caterers continue to reduce the amount of salt they add to food if we are to save the maximum number of lives.
The targeted reduction in the UK was 3.5g salt/day from 9.5g to the current UK maximum target for salt of 6g, however this study clearly demonstrates that a greater reduction in salt intake would have a much greater benefit".
British Medical Journal 2009; 339:b4567
"Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies"
Authors: Strazzullo, P; D'Elia, L; Ngianga-Bakwin, K; Cappussio, F.