The neural tube is the part of an embryo that becomes the brain and spinal cord. Defects happen when a portion doesn’t close properly, something that affects about 64 pregnancies in New Zealand every year.

Most are cases of spina bifida, which in severe instances causes the spinal canal to remain open along several vertebrae in the back, causing membranes, spinal cord or nerves to protrude at birth, forming a sac. Anencephaly, David Maddox’s condition, is the other main type, happening when the upper tube doesn’t close.

Such pregnancies are often terminated. Spina bifida can result in severe and lifelong disability. Almost all babies born with anencephaly die soon afterwards.

Getting adequate folate, a natural B vitamin found in foods such as leafy green vegetables, can considerably reduce (not eliminate) the risk of neural tube defects, if enough is consumed before and in early pregnancy.

It’s very difficult to get enough from diet alone, and blood folate levels in most Kiwi women of childbearing age are too low to give protection. That’s why women are advised to take folic acid tablets at least four weeks before conception and for the first 12 weeks of pregnancy.

However, more than half of pregnancies aren’t planned - a proportion that rises for young mothers (83 per cent), Māori (75 per cent) and Pacific Kiwis (71 per cent). When those women realise they’re pregnant it’s often too late - the neural tube closes 15-28 days after conception.

Countries that have made it compulsory for folic acid (the synthetic version of the vitamin) to be added to staple foods include the United States (in cereal grains since 1998), Canada (in flour and bread since 1998) and Australia (bread-making flour from 2009).

Those nations have lower estimated defect rates than New Zealand and other mostly European countries that encourage companies to voluntarily add folic acid to products.

Folic acid is added to bread-making flour in Australia - a relatively simple step given the small number of millers. New Zealand took a more complicated approach of adding it as non-organic bread is made, amidst concerns about the infrastructure needed for flour millers and exports.

The change was announced in 2007, and hailed by Food Safety Minister Annette King as “a triumph for humanity and common sense”. Fortification alone wouldn’t provide the recommended amount of folic acid, King stressed, and women planning a pregnancy must therefore also take folic acid supplements. However, “it will be enough to make a difference” and prevent four to 14 neural tube defects every year.

Fortification was to start in September 2009. By then a fresh-faced John Key was Prime Minister, the country was clawing back from the global financial crisis, gripped by David Bain’s retrial and acquittal, and horrified by the police standoff with Napier gunman Jan Molenaar.

A debate about folic acid in bread joined those headlines, after an opposition campaign by the Bakers’ Association and Food & Grocery Council, a group representing food manufacturers and suppliers and led by new chief executive and former National MP Katherine Rich.

In a media blitz the same warnings were repeated: researchers were asking whether too much folic acid could fuel ill-health including certain cancers; a pregnant woman would need to eat 11 slices of bread a day to get the recommended level; and bakers couldn’t consistently dose each loaf.

“Minister for Food Safety Kate Wilkinson faces an interesting test,” Rich wrote in a Herald opinion piece titled Added risk, any way you slice it.

“Will this centre-right politician - who campaigned vigorously on ridding New Zealand of the nanny state - endorse such a major intervention?

“Regulators [would] turn from targeted health programmes for small numbers of women at risk to a programme of effective mass-medication - dosing every man, woman, and child.”

Wilkinson labelled the policy “a mess that we’ve inherited from Labour”, and declared herself concerned about too much folic acid causing cancer.

She appeared on TVNZ’s Q&A programme, and was heavily criticised by Green MP Sue Kedgley for not stopping the initiative. Presenter Paul Holmes asked why she was putting “possible poison” in his bread that might give him prostate cancer again: “You could be threatening the health of this nation…we appear to have lost our food sovereignty to Australia.”

A week later Prime Minister John Key kicked for touch, deferring a decision until May 2012. Reaction broadly split into two camps: dismay by public health clinicians and scientists, and support from industry and worried members of the public.

“Quite simply I love my bread,” submitted David Findlay of Gisborne. “With folate added, bread may now not be good for me.”

“Dear Minister,” emailed Simon Oldershaw. “Do you really expect a pregnant woman to eat 11 slices of bread a day? Maybe chocolates dipped in peanut butter or some other craving.”

Bread-manufacturers submitted that the risks raised in the media hadn’t been refuted properly, and therefore “we would be negligent in dosing our customers with folate”. George Weston Foods NZ, baker of brands including Tip Top, raised potential side-effects including prostate cancer and anaemia - but said it was willing to voluntarily expand its range of fortified breads.

That didn't make sense to Massey University’s human nutrition and physiology division. “If consumer safety is at risk (which we do not believe it is) then allowing any bread to carry this level of folic acid is irresponsible,” its staff pointed out. “Government policy should not be driven by lobbyists with vested interests.”

The Ministry of Health, College of Obstetricians and Gynaecologists, College of Midwives, Pharmaceutical Society, College of Physicians, NZ Nurses Organisation, primary health organisations and individual public health experts and GPs were strongly supportive of mandatory fortification.

The Paediatric Society accused industry of a PR campaign “designed to minimise the opportunity for the scientific arguments in favour of folic acid fortification to be presented to the public, and to maximise public anxiety”.

Dr Joanne Dixon, a leading geneticist made an Officer of the NZ Order of Merit in 2016, attacked the “11 slices a day” line as a distortion of facts, given “this would be the case if women were only to eat bread and nothing else” - fortification alone wasn’t meant to provide the daily recommended intake, but would still reduce the risk.

Lyall Thurston, spokesman for the Coalition of Parents of Children with Spina Bifida, warned the Government it was sentencing dozens of kids to death or severe disability.

“Public resistance is based on an extremely clever commercial campaign based on misinformation and catch phrases that, despite our many attempts to correct in the media, still reverberate around hairdressers, cafes and taxis around the country.”

Food safety officials told their minister the health issues had already been carefully considered.

“There is strong evidence for the effectiveness...and no evidence of harm,” they reiterated in a briefing. “In short, [mandatory fortification] is supported by the science.”

Wilkinson - who declined to comment for this article - stuck with the postponement, then in 2012 announced a voluntary system aiming to have up to half of packaged sliced bread fortified (about 38 per cent currently is).

“The decision that was made was really based on consumer choice rather than the science...you can have scientists arguing black and scientists arguing white,” she explained. "I’m not a scientist. The submissions clearly showed consumer choice was the most preferred option."

After mandatory fortification in Australia the rate of neural tube defects dropped by 14 per cent overall, 74 per cent for indigenous women and 55 per cent for teenage mothers.

Partly because of those findings, our Ministry of Health asked the PM’s Chief Science Advisor and the Royal Society to assess benefits and risks. An expert panel led by Sir Peter Gluckman dove into all evidence, including from clinical and population studies.

Their peer-reviewed report was clear: unequivocal benefits of mandatory fortification of packaged bread outweigh any potential adverse health effects, with “no evidence of harmful health effects of folic acid supplementation in adults, at least at low doses in the range suggested for fortification”.

Most data suggests no cancer link, the June 2018 report found, but some limited evidence from genetic studies suggests, for some people, higher blood folate is weakly associated with increased risks of colorectal and prostate cancer, and lower risks of breast and total cancer.

“The associations seen in the genetic studies are not necessarily causal, and their public health significance remains uncertain especially when compared with the undoubted benefits of mandatory folate fortification,” the scientists and panel of health experts agreed.

Last year the Ministry for Primary Industries (MPI) released its own report that concludes: “If mandatory fortification of bread had occurred in 2009, it is estimated that 120 to 171 pregnancies affected by a neural tube defect could have been prevented over the last 10 years.”

More than half of such pregnancies are terminated or result in stillbirths. The real toll is likely bigger, because miscarriages that happen earlier in pregnancy aren’t counted.

MPI called for feedback on three options: keep the status quo; boost the voluntary target to 80 per cent; or mandatory fortification of all non-organic bread, wheat flour for bread-making, or wheat flour.

Wheat flour would cover bread, cake, pastry or plain, and prevent an estimated 252 to 405 neural tube defects over 30 years, compared to the current voluntary regime. However, it may result in children getting too much folic acid.

Officials don’t see the same risk in fortification of bread. Adding folic acid in the breadmaking process could stop up to 270 extra cases over 30 years, but thousands of bakeries would have to test their products.

Fortifying non-organic wheat flour for bread-making (as happens in Australia) is estimated to prevent an extra 162-240 cases over three decades, and save $32 to $54 million. Fortification would be 2-3 milligrams per kilogram of flour.

Overall, the bread and bread-making flour scenarios were estimated to reduce neural tube defects by approximately 10-20 per cent, compared to current fortification.

MPI’s work is paused because of the whole-of-government Covid-19 response, but O’Connor says he wants mandatory fortification approved before the election (a two-year transition period is proposed).

Fortifying all non-organic bread-making flour (his preference) has the backing of the Green Party - a big shift, after its past opposition. However, a roadblock looms in the form of NZ First. Cabinet will need to sign-off the change to the food standard shared with Australia.

“I am currently frustrated with New Zealand First’s view, which at this point does not support mandatory fortification,” O’Connor says.

“I would rather seek support across the coalition parties for this, given its importance. And I was progressing that conversation before Covid hit us.”

The Baking Industry Association didn’t respond to requests for comment. The Flour Millers’ Association, which represents the country’s six flour mills, says if mandatory fortification of flour is chosen, its preference is bread-making flour. Cost estimates for needed equipment are pending.

Secretary Andy Worrill says his members acknowledge that “robust research has been undertaken to cover all aspects of food and people safety, as well as unequivocal evidence of global success in introducing mandatory fortification of folic acid to reduce the incidence of neural tube defects”.

The National Party caucus will discuss any position put forward by the Government.