MP Rodney Hide warned New Zealand Food Safety Minister Kate Wilkinson against mass medicating bread with folic acid three months ago - a month before the Herald on Sunday broke the story.

Hide, as Minister of Regulatory Reform, said he was "shocked" to learn breadmakers were being forced to add folic acid to all bread and urged Wilkinson - who does not eat bread - to delay the decision. In his April 16 letter, Hide expressed concerns about the lack of choice and potential health risks linked to folic acid.

Ireland and the United Kingdom had recently postponed their plans to force breadmakers to add folic acid because of concerns about links with cancer, he wrote.

"Choice is something that is very important to my party and I had thought to yours ... I don't think the New Zealand public will be happy to find out that there are plans to mass-medicate 4.3 million of them through a product they have no choice but to consume."

Wilkinson, who does not eat bread because she is gluten intolerant, said in a statement she was aware of Rodney Hide's concerns.

"The Prime Minister has sought further advice and we are working to find a suitable solution."

Last week Hide said New Zealand had rejected "the nanny state" in the last election.

"It seems to me the only argument in favour of it is we might upset the Australians which I thought was a plus."