Researchers calling for a 'salt tax' say it could add years of life to thousands of people and save the country millions of dollars.

A study by researchers at Otago University's Wellington Campus looks at eight interventions to lower dietary salt by a third over several years.

Professor Nick Wilson acknowledgess there's concern from industry that, if the measures are voluntary, some companies will hold back.

He says if the Government acts with regulations, then industry is much more likely to be cooperative, but he admits introducing a 'salt tax' is the second best strategy.

"It actually gained revenue up to $450 million a year for the government, which could then be plowed in to healthy meals for kids at school, or subsidies on fruit and vegetables."

Professor Wilson says its a very easy tax in theory to implement because there is just one salt producer in the country.