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Am J Clin Nutr. 2012 Sep;96(3):613-21. doi: 10.3945/ajcn.111.026633. Epub 2012 Aug 1.

Unmetabolized folic acid prevalence is widespread in the older Irish population despite the lack of a mandatory fortification program.

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  • 1UCD School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland.



In 2006 the Food Safety Authority of Ireland recommended mandatory folic acid fortification of flour for the prevention of neural tube defects in addition to the existing extensive voluntary folic acid fortification culture in place there. This recommendation is now suspended until further scientific evidence surrounding safety becomes available. The safety issues include concerns about the masking of vitamin B-12 deficiency and potential cancer acceleration, both of which may be of concern for the elderly population.


The aim of this study was to measure the basal (fasted) concentrations of unmetabolized folic acid in the plasma of an elderly population group exposed to this liberal voluntary fortification of foodstuffs in Ireland.


We invited participants aged 60-86 y from the Lifeways Cross-Generation Cohort Study to participate in this project. After providing informed consent, the participants were invited to provide fasting blood samples and to complete a standard food-frequency questionnaire and a questionnaire on recent and habitual intakes of folic acid. Samples were assayed for total plasma folate, red blood cell folate, homocysteine, and unmetabolized folic acid.


A total of 137 subjects with a mean age of 67.4 y were studied. Unmetabolized folic acid was detected in 94.1% of the cohort with a mean concentration of 0.39 nmol/L (range: 0.07-1.59 nmol/L), accounting for 1.3% of total plasma folate.


These results indicate unmetabolized folic acid in plasma in most of this elderly Irish cohort, even after an overnight fast. These results should be considered carefully by those legislating in this area.

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