New Zealand opposition party members are calling on the government to fortify the country's flour supply and bread output with folic acid, following reports of the success of a similar program in Australia.

New Zealand Labour Party Food Safety spokesperson, Dr Ashraf Choudhary, referenced a recent study that found blood folate levels in Australia have increased since the country began fortifying its bread supply in September 2009.

"Three slices of bread containing folate a day could save $39m per year and most importantly could prevent up to 14 Spina Bifida (neural tube defects) cases annually," Dr Choudhary said in press reports.

Deciding whether to fortify food supplies with folic acid or not is an issue that has left many governments confused. While the B vitamin's ability to benefit women of childbearing age and reduce neural tube defects in newborn babies is well-founded, it has also been linked with some cancers, especially among the elderly and even among babies.

Australia joined places like the United States, Canada and Chile when it began fortifying bread products mandatorily after a Food Standards Australia New Zealand (FSANZ) safety review found no inherent safety issues.

Along with Australia, New Zealand did commit to folic acid fortification of bread products in 2007, but baulked at the last moment over the cancer concerns.

The UK has also been considering mandatory fortification, but has held back due to the cancer links, despite advocacy from the UK Food Standards Agency (FSA), which says dozens of babies can avoid neural tube defects if fortification goes ahead.

The Institute of Food Research (IFR) has highlighted some of those concerns that include increased risk of certain types of bowl cancer, cognitive degeneration in older individuals who have depleted levels of B6 and B12, and cardiovascular disease.

"The concern is that the risks (associated with mandatory fortification) make take 10 to 20 years to emerge. So we may have to wait another 10 years to see its full effects," the IFR's Dr Sian Astley told this publication in 2009.

At the time a Department of Health spokesperson said: "We will now consider their (FSA's) recommendation for the introduction of mandatory fortification of flour with folic acid alongside controls on voluntary fortification."

A survey of the effect of the fortification programme in Australia found a 77 per cent reduction in low serum folate levels after analysing more than 20,000 blood samples collected from a varied group of hospital patients between April 2007 and April 2010. The 77 per cent drop occurred between April 2009 and April 2010.