Mandatory Folic Acid Fortification 

Not as Wise as It Sounds… 

When the UK government confirmed that all non-wholemeal wheat flour [including organic] will be mandatorily fortified with folic acid from 2026, the announcement was framed as an unequivocal public health win.¹ The stated aim is to reduce neural tube defects [NTDs] such as spina bifida by around 20%, preventing roughly 200 cases per year. Flour is already fortified with calcium, niacin, thiamine and iron, so adding one more nutrient might seem like a minor adjustment. 

But the simplicity of the policy masks a deeper and more uncomfortable question:  

Is it wise to medicate an entire population; men, children, older adults, and women not planning pregnancy, to target a relatively small subgroup?  

And what do we know about the long-term effects of chronic folic acid exposure in people who do not need it? 

This is not a fringe concern. Even mainstream reporting acknowledges that the policy has been met with apprehension and that some people are ‘unconvinced that its inclusion is a positive step forward for public health’.² The government’s own framing emphasises that half of pregnancies are unplanned, and that uptake of preconception folic acid supplements is low.³ These are real issues. But they do not automatically justify universal exposure. 

The government estimates that fortification will prevent around 200 NTD cases per year. To understand the scale of intervention required to achieve this, consider the population exposed: 

Approximately 67 million people in the UK will consume folic acid fortified flour in some form: bread, pastries, pasta, sauces, and countless processed foods.⁴ Even if we conservatively assume that only 50 million consume wheat flour regularly, the numbers needed to treat (NNT) become stark: 

• Target outcome: prevent 200 NTD cases per year 

• Population exposed: ~50,000,000 

• NNT: 50,000,000 ÷ 200 = 250,000 

In other words, a quarter of a million people must be exposed to mandatory folic acid fortification to prevent a single case of NTD. 

Please feel free to correct my maths if I am wrong…. 

Normally, public health interventions often involve high NNTs, but this is unusually high because the target group of women in the first 12 weeks of pregnancy is small relative to the whole population. And even within that group, only a small proportion of the women are folate deficient. 

This raises a legitimate ethical question: is it proportionate to expose the entire population to a synthetic nutrient to reach a small minority who could instead be supported through targeted measures? 

The Food Standards Agency may emphasise that folic acid fortification has been used in more than 60 countries and that levels are ‘well below established upper safety limits’.⁵ But this reassurance glosses over several unresolved issues. 

Folic acid is a synthetic compound that must be converted by the body into its active form. Some people [particularly those with MTHFR gene variants] convert it inefficiently. Unmetabolised folic acid has been detected in the bloodstream of people in countries with mandatory fortification, and its long-term effects remain uncertain. 

Chronic exposure in men and older adults has not been meaningfully studied, because the policy is designed for women who may become pregnant, yet: 

• Men will consume it daily for life 

• Postmenopausal women will consume it daily for life 

• Children will consume it throughout development 

• Older adults, who already face risks of masking B12 deficiency, will consume it daily for life 

None of these groups benefit from NTD prevention, yet all will be exposed. 

The dose is small, but the exposure is lifelong; a typical slice of fortified bread will contain around 50–60 µg of folic acid. That seems trivial. But consider cumulative exposure: 

• Daily intake from bread, pasta, cereals, and processed foods 

• Plus supplements for those who take multivitamins 

• Plus fortified foods already on the market 

Over decades, even small doses accumulate into a significant lifetime exposure, especially in people who do not need it. 

I know the government’s rationale seems clear: many pregnancies are unplanned, and supplement uptake is low. But this is not the only way to address the issue. 

But, could they not; 

• Use targeted supplementation programmes to women trying to conceive 

• Distribute free folic acid in pharmacies to any woman in early pregnancy 

• Enhance preconception education 

• Automatic supplementation in contraceptive and fertility services 

Instead, the government has chosen the bluntest possible tool of medicating the entire population to reach a small minority. 

Mandatory folic acid fortification is presented as a simple, evidence based intervention. But the evidence is more nuanced, the target group is small, and the longterm effects of universal exposure remain insufficiently understood.⁶ 

Preventing NTDs is unquestionably important. But so is ensuring that public health interventions are proportionate, evidence based, and ethically justified. When the NNT is 250,000, and when the intervention affects every man, woman, and child in the country for life, the burden of proof should be extremely high. 

At present, I do not think that burden has not been met. 

Sources: 

¹ UK Government / Department of Health and Social Care (2024). Birth defects prevented by fortifying flour with folic acid. Press release, 14 November 2024. Available at: https://www.gov.uk/government/news/birth-defects-prevented-by-fortifying-flour-with-folic-acid 

² Yahoo! News UK / Cosmopolitan UK (2025). Why there’s so much fear around folic acid being added to bread – and what the science actually says. Published 29 December 2025. 
Available at: https://uk.style.yahoo.com/why-much-fear-around-folic-070000846.html 

³ Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT), Folic Acid: Updated Statement (Food Standards Agency 2023) 
– “As many women do not take supplements and many pregnancies are unplanned, the rate of affected pregnancies has not significantly changed…” 

⁴ Food Standards Agency, “Folic acid” (GOV.UK, 2024) — notes that wheat flour is “widely consumed… by most people”. 
Office for National Statistics, “United Kingdom population midyear estimate” (2025) — gives a population of approximately 67 million. 

⁵ “The use of wheat flour as a product for folic acid fortification has been adopted in more than 60 countries worldwide (including Australia, Canada and the USA), either mandatorily or voluntarily.” https://www.food.gov.uk/safety-hygiene/folic-acid 

⁶ NIH Office of Dietary Supplements. “Folate – Health Professional Fact Sheet.” 

https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/?uid=08c69f616b21cs16

“When the capacity of dihydrofolate reductase is exceeded, unmetabolized folic acid can be present in the blood… Whether unmetabolized folic acid has any biological activity… is not known.” 

“Some research has found associations between folic acid supplementation and increased cancer risk.” 

“In addition, a 2018 prospective study found that folic acid intake from fortified foods and supplements was positively associated with a risk of cancer recurrence among 619 patients with non–muscle-invasive bladder cancer, whereas natural folate intakes showed no significant association. Higher plasma folate concentrations have also been associated with an increased risk of breast cancer in women with a BRCA1 or BRCA2 mutation. A secondary analysis of the study by Cole and colleagues found that folic acid supplementation significantly increased the risk of prostate cancer.” 

These statements are all referenced in the fact sheet.  

Image Ref: ; BuhaM, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons