12 January - 20 June 2016

Should flour be fortified with folic acid to prevent neural tube defects?

The fortification of white flour with folic acid, currently seen in 81 countries (including Australia and the USA), would help eliminate cases of neural tube defects such as Spina Bifida according to a recent study published in Public Health Reviews by UK researchers. However, exceeding the current tolerable upper intake level of 1mg/day has stopped widespread fortification.

The fortification of white flour with folic acid, currently seen in 81 countries (including Australia and the USA), would help eliminate cases of neural tube defects such as Spina Bifida according to a recent study published in Public Health Reviews by UK researchers.  However, exceeding the current tolerable upper intake level of 1mg/day has stopped widespread fortification.

Neural tube defects (NTDs), including both Anencephaly and Spina Bifida, are serious birth defects occurring when the neural tube does not close sufficiently, leading to severe disability or termination. These can be prevented by prescribing folic acid pre or during early pregnancy, despite only 31% out of 0.5 million women in the UK taking folic acid prior to conception. Folate, a B vitamin found naturally in food, contains the biologically active yet stable molecule folic acid. Its high stability to thermal processes and increased bioavailability when used as a fortification method means it is an ideal candidate for flour fortification.

The review reports the findings of a randomised double blinded trial in 1991, which found that 4 mg of folic acid each day before and during the first trimester of early pregnancy helped to prevent between 71-83% of neural tube defects. It concluded that neural tube defects are a result of vitamin deficiencies, which could be prevented at an individual level with folic acid prescription but also at a population level with fortification of a staple food (such as flour, already fortified with minerals such as calcium and iron). The fortification of flour with folic acid not only would improve the quality of life of many newborns but could help prevent megaloblastic anaemia in pregnant women. The review report that those countries who have introduced mandatory folic acid “have shown a clear reduction in the incidence of NTDs” and in the USA folate deficiency anaemia has “nearly been completing eliminated following mandatory folic acid fortification of cereals.”

The review reports that despite folic acid not found to negatively impact individuals, a tolerable upper intake level (the maximum daily intake of a certain nutrient that will not cause harmful side effects for most people within the population) of 1mg/day was formed. Wald et al report that this arose due to concern over mis-diagnosing Vitamin B12 deficiency and treating with folic acid supplementation. Both Vitamin B12 and folic acid deficiency lead to megaloblastic anaemia, however with B12 deficiency a neurological disorder also arises. Therefore treating with folic acid would appear to cure the anaemia, however the neurological disease would still be present. With advancements in modern science, specific assays have been developed to distinguish between B12 and folic acid deficiency therefore those who present with anaemia could now be diagnosed with B12 deficiency. Delayed diagnosis with increased folic acid consumption was also voiced, however studies investigating B12 deficiency with patients consuming either >5mg or between 0.33-2.5mg/day concluded, the rate of disease progression was not impacted by the level of folate consumption.

Fortification of flour with folic acid will inevitably lead to women exceeding the upper tolerable limit set for folic acid, however it would help prevent over 5 million preventable neural tube defects. The possibility of harm, in this case the misdiagnosis or progression of B12 deficiency, and tolerable upper limit (which the authors make a case for being scientifically unjust) are acting as barrier to the perceived health benefits that would occur if folic acid consumption was increased. 

RSSL provides a full vitamin and mineral analysis services to assist you with labelling, due diligence, claim substantiation and stability. To find out more please contact Customer Services telephone 0118 918 4076 or e-mail enquiries@rssl.com

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