Q+A Dr Andrew Marshall Interview Transcript 08/07/12
Paediatric Society says claims by an Oxford Professor that folic acid in bread could lead to a couple of hundred more cancer cases each year are "completely false" and "selective".
"It's not true it will increase cancer. It reduces cancer overall."
Mandatory fortification of bread with folic acid could prevent deaths from strokes - as many as 124 per year.
About 24 neural tube (NTD) pregnancies a year could be saved if folic acid in bread was made mandatory.
Mandatory fortification could save about two-thirds of all NTD cases.
Number of women with "good levels of folate in their blood" has doubled since voluntary programme began two years ago, but that's only half of the number that would be achieved if it was made mandatory.
Freedom of choice?
"If you can do something that's safe and effective and doesn't cause harm, then it's better to do that for the whole population, even though you know that only certain sectors of the population will achieve the greatest benefits from that."
Q+A, 9-10am Sundays on TV ONE and one hour later on TV ONE plus 1.
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First and foremost, a couple of hundred more cases of cancer per year - what are your responses to that?
ANDREW MARSHALL - Paediatric Society of NZ
Completely false. If we look at the United States where they introduced mandatory fortification in '98, there's been a reduction in all cancers since that time. So it's not true it will increase cancer. It reduces cancer overall.
GREG What are your thoughts on Dr Smith's science, because, as he said, he's done extensive studies on an extensive number of people.
ANDREW I've reviewed his studies. He is very selective in the studies he chooses. He talks about a meta-analysis of 38,000. There's a different meta-analysis using a similar population - some of the studies overlap - of 35,000, which is much stronger. It shows no relationship with cancer, no increased risk, no statistical risk. So he's selective in the studies he chooses, and he's chosen a weaker study which showed a borderline. Even the writers of that study said there was no definite increase; it was borderline.
GREG One point he did make on the other side of the issue, though, is up to five less cases per year of spina bifida. Is that accurate?
ANDREW No, it's not. His calculation is- Again, he does a lot of extrapolation. Whenever he's extrapolating to his favour, he will go one way, and if it's talking about the risks, he'll extrapolate up. If he's talking about the benefits, he extrapolates down. The Ministry of Primary Industry Report is a very balanced view. It's done a very robust calculation. The numbers are about 24 neural tube pregnancies a year that are likely to be prevented with mandatory.
GREG And that's 24 less, and so how many are likely to still happen? Give us the bigger picture on those numbers.
ANDREW Sure. The bigger picture is about- You can usually prevent about two-thirds. So there are probably about 10 to 20 neural tube pregnancies a year that we can't prevent, and there's a floor level or a baseline that places around the world that have introduced mandatory can't get below. So there's some that's folate responsive and some that isn't.
GREG Ok. Let's get down to the real specifics. This is the clip we saw before briefly. Three years ago Paul Holmes asked Kate Wilkinson if adding folic acid was 100% safe. She said the science then was light. Do we have new research that you can categorically say there is no risk of cancer as a result of putting folic acid in bread.
ANDREW I can, and the science is robust. The Clarke meta-analysis of 35,000 people is pretty definitive, and it's a very high quality study. And the USA Cancer Registry, which is again very robust - population incidence - no increased risk. In fact, a decreased incidence of cancer throughout. One of the other things is we talk about the benefits in terms of neural tube defects. There's something else that's come from the United States, and that's the reduction in death from stroke. Now, a significant decrease in stroke deaths since mandatory fortification in the USA. Using the United States' calculations, in fact from David Smith's paper, so he's likely to underestimate it, it's about 124 reduced stroke deaths in New Zealand a year.
GREG So why is it not in Europe, and why are so many of the countries, in the 74 we mentioned before, it's not mandatory; it's a voluntary thing. If it's that good, why is not everybody doing it?
ANDREW Well, I think 74 are mandatory, and then there are a number of others such as in Europe where it's voluntary. One of the reasons is that some populations have a lot of foods that are already fortified but not in a mandatory way. And it means when they look at the population blood levels of folate, those populations have effectively very good levels. And so the amount of extra gain you could get is limited. What's important from the New Zealand research is that we introduced voluntary in 2009. In that two-year period, voluntary has, along with people eating more fortified breakfast cereals, has increased the number of women - about double the number of women - who have good levels of folate in their blood. So the amount that you gain from voluntary is about halfway what you can get with mandatory.
GREG Let's go back to the American example. I understand that the number of neural tube defects in this country are falling around about in parallel with what's happening in the United States anyway. So is there any need to introduce this as well, or are we doing pretty well anyway?
ANDREW They are reducing, but our calculations and the calculations from the Ministry of Primary Industry, their scientific paper, which is a very unbiased, high quality review, suggests that we're about halfway there, that we have reduced the numbers, but we can reduce them by another 24 per year with mandatory above what we have already achieved through voluntary.
GREG Ok. Let's talk about amounts. It's between 0.8g and 1.8g per loaf. My understanding as well is if a woman who's pregnant is to get any benefit from this to prevent NTD, she's going to have to eat something like 12, 13 slices. No one eats that much bread every day. Is that actually going to be enough that this is an effective amount?
ANDREW Well, again, the United States research is really robust, and what they've shown in the United States is with mandatory, the average amount of increase in the US population since mandatory is 132 micrograms of folate. So that's the equivalent of three to four slices of bread a day. And that increase - three to four slices a day - takes the whole population up to the point where you've got the floor level, the minimum amount of neural tube defects possible.
GREG Ok. Let's get on to the other side of this. Mass medication - he's saying it's mass medication. We're also led to believe, if you listen to the other side of the debate, that people haven't been made aware of exactly what's happening. It was meant to go ahead three years ago. It didn't. What do you say to that?
ANDREW It's a natural vitamin. I think Dr Smith is somewhat disingenuous saying that there's a difference between folic acid and folate. Yes, folic acid is the chemical that you take, and it's converted in your body into folate, so it is a vitamin.
GREG But he is an Oxford don. You presume you know what he's talking about. Is there another agenda here we're not aware of?
ANDREW Um, the paper that Smith and Refsum have written was commissioned by the Bakers Research Trust and the Food and Grocery Council, so I leave you to draw your own conclusions.
GREG Well, I can actually draw my own conclusions. My conclusion, I guess, would be it's going to be really expensive, so they want somebody out there saying, 'No, no. It's bad.' It's not expensive. It's about half a cent a loaf. About $1.29 million a year for the whole bread industry in New Zealand. It's nothing. It's not going to be a big cost. So, again, why would they be pushing this barrow, this anti-barrow so hard?
ANDREW Well, I think there's a philosophical thing here about choice and about the concept that the state should never do something for the whole population to help certain members of the population. So it's that thing about autonomy and choice. And a public health perspective is it is legitimate. If you can do something that's safe and effective and doesn't cause harm, then it's better to do that for the whole population, even though you know that only certain sectors of the population will achieve the greatest benefits from that.
GREG But if this does become mandatory, and whatever terminology you want to use - it's naturally occurring, it's medicine, it's not medicine - if it does become mandatory, people like men, being the obvious example, are going to eat it who don't need it.
ANDREW It's interesting. I mean, again, as even Professor Smith, who's a folate hater- That's perhaps unfair. As even he says, everybody needs folate. We know that actually if you're folate deficient, bringing your levels up to normal levels actually decreases your cancer risk. So there's an argument if you take excessively high supplemental doses whether that causes cancer. Even if you take really high doses, and we're talking about one loaf of bread a day - that kind of dose - that's where the cancer risk evidence comes from. It doesn't come from the dose that you get from a couple of slices of bread.
GREG Ok. What you've heard, what you've seen so far, what is likely to be the outcome? Are we going to have mandatory folic acid in our bread by September, or is that now pretty unlikely?
ANDREW Well, I think that it should happen. I think that the Ministry of Primary Industry Report is very clear to the government about the benefits and is very clear about the absence of risks. So it's up to the politicians to decide. The Paediatric Society of New Zealand strongly supports mandatory fortification to help all members of the population, not just unborn babies, but, as I say, people dying of stroke.
GREG We will have to leave it there. Dr Andrew Marshall, thank you so much for your time.
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