The model behind the mandate
Dr Clare Craig
Multiple countries have already added folic acid to their food but the decisions differ in terms of the dosage and the types of food affected.
| Country | Minimum | Maximum | What the law covers | Can it be avoided? |
| United States | 154 µg/100 g | none | only flour and grain products sold as “enriched” | yes, unenriched and organic flour are both free of it |
| Canada | 150 µg/100 g | none | all white flour and every food made with it | no |
| Australia | 200 µg/100 g | 300 µg/100 g | wheat flour for bread-making | yes, organic flour and all non-bread flour are exempt |
| New Zealand | 200 µg/100 g | 300 µg/100 g | wheat flour for bread-making | yes, organic flour and all non-bread flour are exempt |
| United Kingdom | 250 µg/100 g | none | all non-wholemeal wheat flour, organic included | no |
Table 1: What each country mandates, which foods it applies to and ability to opt out
The dosage being put into British food is 62 percent more than the United States, 67 percent more than Canada and 25 percent more than the Australian and New Zealand minimum. How was the decision reached for Britain to have the highest mandatory concentration of these five nations? The British policy also has minimal opt outs with only Canada covering all white flour and everything made from it in the same way, albeit at a considerably lower dosage.
Three wildly different claims about benefit
Despite all these countries aiming to achieve broadly similar daily exposure to folic acid, when scientists measured what was delivered they produced very different results. Furthermore, the claimed reductions in neural tube defects later attributed to folic acid differ dramatically.
| Country | Target dose per day in women | Folic acid actually delivered | Reduction claimed |
| Canada | 100 µg/day | 70 µg/day | 46% |
| Australia | 100 µg/day | 159 µg/day | 14.4% |
| United States | 100 µg/day | 100 to 240 µg/day | 28% |
| United Kingdom | 100 µg/day | 90 to 100 µg/day, modelled | 15 to 22%, modelled |
Table 2: Target dose, achieved dose and claimed benefit by country
There are differences in how the benefit was measured. For example, USA counted affected live births and left out terminations while Canada included live births, stillbirths and terminations. Australia compared eighteen months of fortification against a single point estimate for the pre-fortification period. None included the background year on year fall that has been seen for decades in their sums.
Rather than compare the three claims with each other, each country’s dose can be put into the British model to see what that predicts compared to what that country reports.
The UK impact assessment includes the equation the British benefit is calculated from. The estimate for neural tube defects per 1000 pregnancies is calculated as 37.5 divided by the square root of the folic acid intake. That equation is the basis of the claimed reduction of 20 percent for the UK. If we assume that the UK average of 251 micrograms of natural folate per day is uniform across the countries then a like for like comparison can be made with only the folic acid dose changing.
| Country | Delivered | What the equation predicts | What was claimed |
| Canada | 70 µg/day | 12 % | 46 % |
| United Kingdom | 90 to 100 µg/day | 14 to 16 % | 15 to 22 % |
| Australia | 159 µg/day | 22 % | 14.4 % |
| United States | 100 to 240 µg/day | 16 to 29 % | 28 % |
Table 3: The effect of each country’s delivered dose according to the UK model and the outcome that government claims
The USA data suggests two values for how much folic acid ends up in people. At the lower end, the model claims it should equate to a 16 percent reduction in neural tube defects and at the higher end a 29 percent reduction. The latter fits the government’s claim. The exposure rate in Australia would be predicted to result in a 22 percent reduction if the model could be trusted but the government claim only 14.4 percent. Canada is the real outlier with a claimed reduction that is four times the size of the model prediction.
How can the discrepancy be explained? One way is to suggest there was a big difference in background dietary folate intake. Ordinary diets supply between 200 and 300 micrograms per day. For the American figure to fit, American women would need to have been consuming between 108 and 260 micrograms of folate a day before fortification. The upper end is an ordinary figure and entirely plausible. For the Australian figure to fit, Australian women would need to have been eating about 439 micrograms a day. That is near impossible without folic acid in the food. For the Canadian figure to fit, Canadian women would need to have been consuming about 29 micrograms of folate a day prior to fortification which is far too low for any diet. A woman eating 29 micrograms a day would be severely deficient and starving.
The evidence from Canada is often held up as a cut and dry success story referenced by the UK government. The model is relied on to make the 20 percent reduction claim but the same model cannot compute what happened in Canada.
Caution about overdosing
USA. When the FDA modelled dosages they used three levels, 70, 140 and 350 micrograms per 100 grams of flour. They chose 0.7 milligrams a pound for enriched flour, which works out at 154 micrograms per 100 grams, slightly above their middle dose in their modelling. Activists asked for 250 or 350, arguing that this was well within the limits of safety. The FDA refused because of the risk that at 210 or above the heaviest consumers of grain products would exceed the recommended safety level of a milligram a day, saying,
“There simply is no evidence in the record that such a fortification program would keep folate intakes within the safe upper limit.”
That cut-off only relates to one adverse effect, the masking of vitamin B12 deficiency while permanent neurological damage progresses undetected. The FDA concluded that 140 was the maximum level that would be safe for all groups. It even calculated how many injuries would cancel any benefit, putting the figure at between 386 and 1,228 cases a year of masked B12 deficiency progressing to neurological damage. It therefore capped voluntary fortification of breakfast cereals at 400 micrograms a serving and wrote into the rule that if the share of cereals fortifying at that level rose it would reconsider. How can the FDA decide that 210 micrograms per 100g of flour was not safe, yet the Uk government are mandating 250 micrograms?
Canada. Higher levels were also considered and rejected in Canada because of concern about exceeding the recommended upper intake of 1,000 micrograms a day. The level is a single figure of 150 micrograms per 100 grams of flour with no maximum. That is the same rule Britain has used.
Australia. Food Standards Australia New Zealand, the regulator for both countries, decided on a minimum of 200 micrograms per 100 grams but included a restriction of a maximum of 300. They also restricted it to only wheat flour for bread-making. Organic flour is exempt. Notably, FSANZ accepted that some children would exceed their upper limit so set up monitoring to check on this. Since then, reports have appeared on bread composition, on intakes, on folate status and on neural tube defect rates. They have not published a follow-up on the specific concern of children exceeding the limit.
New Zealand. New Zealand approved mandatory fortification jointly with Australia in 2007. In 2009, when Australia went ahead New Zealand deferred. In 2012, they revoked the requirement in favour of a voluntary scheme. However, in 2021, New Zealand approved it again and it was brought in on 14 August 2023. New Zealand fortifies at the Australian level and targets the same foods. The Ministry for Primary Industries has said, “Organic bread and flour were excluded from the mandatory fortification scenarios because it can no longer be marketed as organic if it contains folic acid. This also allows for some consumer choice for those not wanting to consume folic acid.”
Britain. The UK modelling report did express concern about overdosing. They suggested there should be a cap introduced on exposure from voluntary fortification and supplements. The law has not introduced such a cap. There is also no legal commitment to any monitoring in the regulations.
What foods are included
In 1940s, the FDA decided it would not require mandatory fortification for any food product and that policy is still active. What was introduced in 1996 was a rule to change what food labelled “enriched flour” should contain. Millers are free to sell plain flour or organic flour with no additions. In reality, most flour sold and eaten in USA is enriched so the CDC describes the change that came into force in 1998 as a mandate. Ultimately, enriched flour ends up in a lot of American food products.
Australia and New Zealand mandate fortification only in wheat flour intended for bread-making. As well as organic flour being exempt, cakes, biscuits, pastry and sauces fall outside the mandate entirely.
The Canadian Food and Drug Regulations have the broadest reach in terms of the quantity and range of food containing folic acid. They require that all white flour, and all foods containing it, contain folic acid.
Britain has chosen, not only the highest dose, but the broadest reach akin to Canada but going further because of the mandatory inclusion of folic acid in imported and organic flour, as made clear in their response to our petition. All products manufactured in the UK from non-wholemeal flour will have to have folic acid. The consequence is that it is already in a huge range of products including many products people would not think to check. Wholemeal flour has been exempted but the exemption applies to the flour. Many loaves, advertised as wholemeal, contain white flour and therefore folic acid.
It is also important to note than when estimating dosing the impact assessment assumed the addition of folic acid “would only apply to UK-produced flour”. Therefore 11.3 percent was deducted to account for imports. The regulations require additions to all flour sold here including imported flour. Every exposure in their sums should therefore be adjusted upwards to account for imported flour.
Why has Britain chosen both the highest dose and the widest exposure? Canada had the most draconian policy before, sparing neither organic nor imported flour, but it only demanded 150 micrograms per 100 grams of flour and not the 250 micrograms Britain is demanding.
Why not start at 150?
The UK modelled situations with 0, 100, 200, 250, 300, 350 and 450 micrograms per 100 grams. The American and Canadian levels fall between 100 and 200 and yet this level was never modelled.
On the government’s own estimates, every 100 micrograms per 100 grams raises intake across the population by 40 micrograms a day on average. Looking back at table 1 it is hard to know where that estimate came from. The measured estimates are far higher ranging from 70 to 240 micrograms delivered into people.
Based on their extremely low 40 microgram rise the population would be exposed to 60 micrograms a day with a law demanding 150 micrograms be added. 60 micrograms is the bottom of the target range that the Food Standards Agency had set. It is therefore incredibly odd that this level was not modelled.
If 150 micrograms per 100 grams is used in the government’s own equation, it produces a claimed reduction in neural tube defects of about 10 percent. Remember, that since 1998 USA have used that level and claim a 28 percent reduction and Canada has also used it and they claim a 46 percent reduction [link to Canada paper].
If the British equation is right, the North American results are three to five times too large. Either, the countries whose experience is cited as proof that fortification works have been overstating what it achieved or Britain’s model is very wrong.
