Do you know how much sugar is in tomato sauce? Chef Simon Gault's new weapon in the fight against the sweet stuff

Simon Gault is waging a war against sugar, and the latest weapon in his arsenal is a sugar-free tomato sauce sweetened naturally with vegetables.

The celebrity chef spent three years perfecting the recipe and will be selling bottles of the sauce at the Food Show from Thursday at Auckland's ASB showgrounds.

As well as being healthy, the secret recipe was nearly impossible to tell apart from traditional sugary ketchup, Gault said.

He hopes to see it on supermarket shelves within the next few months and it will be available online as well.

Gault is excited about what he's calling a world-first: a ketchup sweetened entirely by vegetables. Photo / Michael Craig

Gault has been obsessed with our sugar consumption and all its accompanying health problems since being diagnosed with diabetes several years ago.

Despite what people might think, most ketchup is packed with sugar - which is why kids love to smother their food in it, Gault said.

"It's sweet and it's addictive and suddenly they'll eat food they wouldn't normally eat."

He hoped to make a difference by offering a healthy option for a much-loved Kiwi condiment.

"[Sugar consumption] is creating obesity, we have one of the fattest countries in the world with our children. A product like this is going to help us going forward."

Gault is claiming his ketchup is a world first, because even though other low-sugar tomato sauces have been created, none but his are sweetened with only vegetables.

As for what those vegetables are, Gault won't say.

When asked by a fan on Facebook, he simply replied "yummy ones", and when asked by the Herald he was tight-lipped.

The sauce will cost $7.49 for a 475g bottle, which is dearer than a regular bottle.

That was unavoidable Gault said, because vegetables cost more than sugar.

"What we're giving is something that's a lot better for us."

Gault will have a stall at the Food Show this week and on Friday will be taking part in a live cook-off challenge with deputy Prime Minister Paula Bennett.

In a MasterChef-style challenge, Gault will call on Bennett and audience members to take part in a cooking competition, in which they have to follow his instruction in a quick fire mystery box challenge.