A joint report by the Chief Science Advisor and Royal Society Te Apārangi has found the benefits of bread fortified with folic acid would outweigh any potential risk.
Photo: RNZ
Alongside Australia, New Zealand was set to make bread fortification mandatory in 2007, however voluntary fortification was introduced instead in 2012.
More than 80 countries have implemented a mandatory programme.
Co-author of the report, Robert Beaglehole, said only about 16 percent of women of childbearing age are folate sufficient, and taking supplements during pregnancy can often be too late.
"The problem with that is many women get pregnant in an unplanned fashion and become aware of their pregnancy only after the neurological systems have been laid down," he said.
Professor Beaglehole said there could be approximately 10 fewer babies born with neural tube defects such as spina bifida in New Zealand if all bread was fortified with folic acid.
Any risk of cancer from added folate was insufficient towards the birth defects it could help prevent, he said.
Former Prime Minister's Chief Science Advisor and co-author, Sir Peter Gluckman, said there was a very low chance of cancer.
"There is some indirect evidence from some very complex genetic studies that raise the possibility it would reduce the overall levels of cancer, but change the balance, so there's a reduction in breast cancer and possibly a slight increase in prostate and colon," he said.
Sir Peter said if all packaged bread were to be fortified, there would still be options for those in the at-risk group.
"That was one of the reasons why we chose to recommend the fortification of packaged bread, but not artisan bread or flour as a whole, so those people where doctors thought there might be a risk can be recommended not use those breads," he said.
He said neural tube defects like spina bifida are very distressing for the families involved, and there is no doubt fortifying bread reduced the risk.