Imposing statutory limits on the salt content of processed foods could be 20 times more effective than voluntary curbs by industry, finds research published online in the journal Heart.

The Australian researchers assessed the public health benefits and cost effectiveness of different strategies for reducing dietary salt content - a factor known to have a key role in the increased risk of heart disease and stroke.

They looked at the current Australian 'Tick' programme. This enables food manufacturers to buy an endorsed logo for use on product packaging to achieve higher sales in return for voluntarily reducing the salt content of these products.

They also looked at the impact of mandatory reductions in salt content; and professional advice to cut dietary salt for those at increased and high risk of cardiovascular disease.

They then costed the different strategies in terms of their impact on years of good health over a lifetime, and the associated savings in long term healthcare spend. And they compared the results with what would happen if none of these strategies were in place.

They took into consideration the salt content of bread, margarine, and cereals; the tonnage of product sold; average consumption per head of these products; the costs of drafting and enforcing legislation; and systematic reviews of the evidence for the impact of dietary advice from healthcare professionals.

Their calculations showed that 610,000 years of healthy life could be gained if everyone reduced their salt intake to recommended limits (maximum of 6 g a day).

But providing dietary advice to reduce salt intake is not cost effective, even if directed towards those with the highest blood pressure readings, and most at risk of cardiovascular disease. It would only cut ill health from cardiovascular disease by less than 0.5%.

Voluntary industry restrictions on the salt content of processed foods under the current incentive scheme are cost effective, and would cut ill health from cardiovascular disease by almost 1%, which is substantial at population level.

But the health benefits across the population could be 20 times greater if the government imposed mandatory limits, the figures showed, amounting to a reduction of 18% in ill health from cardiovascular disease.

Salt is a cheap ingredient for food manufacturers and is not essential at such high levels, say the authors.

"Food manufacturers have a responsibility to make money for their shareholders, but they also have a responsibility to society. If corporate responsibility fails, may be there is an ethical justification for government to step in and legislate," they conclude.

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