Folic acid in flour: Protecting pregnancies, but at what cost to men?

5 min read – fact checked

In a past BLOGPOST on the September 2024, I wrote about my concerns regarding the UK Government’s decision to fortify non-wholemeal flour with synthetic Vitamin B9 (aka Folic acid). As from December 2026, UK regulations will require non-wholemeal wheat flour to be fortified with 250µg of synthetic folic acid (Vitamin B9) per 100 g of flour ⁽¹⁾. The main public health rationale is to reduce neural tube defects such as spina bifida, which develops very early during pregnancy (fig. 1), often before a woman knows she is pregnant. The policy is intended as a population-wide ‘safety net’, because not all pregnancies are planned and not everyone who could become pregnant takes folic acid supplements ⁽²⁾. By extension, it is very possible that many of the British brands of non-wheat flour, will invariably be available for purchase at several popular stores in Gibraltar.

A QUESTION OF ETHICS
The ethical question is that the intervention isn’t targeted at those who can benefit most, as everyone consuming fortified flour; men, children, post-menopausal women and others, who may not require extra, will invariably be exposed to synthetic folic acid in order to reach women who may become pregnant.The argument that the dose is ‘low’ doesn’t completely address the issue, because total exposure can come from several sources, including other fortified foods, multivitamins, B-complexes, and other food supplements. Cumulative exposure and individual autonomy matters _{^{(1, 3)}}.

MASKING VITAMIN B12?
Vitamin B12 deficiency is another consideration. High intakes of synthetic folic acid can correct the anaemia associated with B12 deficiency without correcting the underlying deficiency, potentially allowing neurological damage to progress unnoticed ⁽³⁾. This is one reason why the 1 mg/day upper level for folic acid exists. Population-wide fortification therefore needs to consider not just the intended benefits, but also cumulative exposure and vulnerable groups, and unintended consequences like these.

ONCOLOGY PATIENTS
Cancer patients is another sub-group worth considering. Folate is essential for cell division, while some cancer treatments work by interfering with folate metabolism. This doesn’t mean cancer patients should avoid folate-rich foods, but additional synthetic folic acid from supplements and fortified foods may be relevant to some treatments and should not automatically be assumed to be harmless or irrelevant. This is another reason why the wider effects of population-wide fortification warrant careful monitoring ^(2,3).

PROSTATE CANCER RISKS IN MEN
There is also an emerging scientific question about synthetic folic supplementation acid versus naturally occurring dietary folate exposure in men. A recent study examining prostate cancer found an association between genetically predicted folic-acid supplementation and increased prostate-cancer risk in men (fig.2), while genetically predicted dietary folate equivalents were not significantly associated with risk ⁽⁴⁾. This does not prove that folic-acid fortified flour may cause prostate cancer, and the research did not directly examine the UK fortification programme, but it does raise an important question about whether synthetic folic acid should be treated as biologically interchangeable with naturally occurring folate when considering population-level interventions, especially for men who may inadvertently by supplementing with folic acid and men with genetically higher risks of prostate cancer, raising important safeguarding issues, and ethical considerations about informed consent.

For men in particular, this raises an interesting debate: they receive no neural-tube-defect prevention benefit from fortification, yet are nevertheless are unnecessarily exposed to synthetic folic acid throughout the food supply, arguably as an increased risk for some vulnerable sub-groups. The potential long-term consequences of fortified synthetic folic acid exposure therefore deserves continued research and monitoring ⁽³⁾, rather than being dismissed simply because the fortification dose is relatively small.

Folic acid fortification in flour thus raises legitimate concerns, of whether it may be proportionate to expose essentially everyone who eats ordinary flour to a synthetic nutrient in order to ensure that a much smaller subgroup has adequate folate at the very early stages of pregnancy? The aim isn’t to question the importance of preventing neural tube defects, that benefit is well established. The question is whether mandatory population-wide exposure is the most appropriate way of achieving it, particularly when targeted supplementation is already recommended for women who may become pregnant.

Men (and women), if you are reading this, and believe this policy deserves further scrutiny, I urge you to SIGN THE PETITION by Dr Claire Craig (fig. 3), calling for the UK Government to reconsider mandatory folic-acid fortification in non-wholemeal flour: Evidence matters in both directions: preventing birth defects is important, but so is properly evaluating unintended long-term consequences of population-wide interventions, especially men at risk of prostate cancer.

Click to sign the petition