The simple threat of a sugar tax could be enough in itself to spur companies on to reduce the sugar content in their products.

The Ministry of Health's Chief Science Advisor has give the Prime Minister 19 points for arguing the case for a sugar tax.

Professor John Potter is also recommended taxing on the volume of sugar, not the sale price.

CEO of Just Water Tony Falkenstein told Kate Hawkesby he believes anything with over eight percent sugar content should be taxed.

"What happened in the UK, is just the threat of a sugar tax at eight percent caused companies to reduce their sugar content remarkably. I mean Ribena reduced their sugar content by 50 percent just to get under the threshold."

LISTEN ABOVE AS TONY FALKENSTEIN SPEAKS WITH KATE HAWKESBY