High folate levels in the older population: implications for fortification in Ireland
The full press release is available here
A new study led by researchers from The Irish Longitudinal Study on Ageing (TILDA) at Trinity challenges claims from some international scientific circles, that having high blood levels of folate (folic acid) increases the risk of poor cognition in older adults, especially in those with low levels of vitamin B12.
The study, published today in the British Journal of Nutrition, forms part of the largest representative study of its kind conducted among older persons.
Both vitamin B12 and folate are essential vitamins for the nervous system and healthy blood cells. Deficiency of folate in early pregnancy can lead to neural tube defects (NTDs) in new-born babies. This is the reason for mandatory fortification of the food supply with folic acid in the US and other countries (but not Ireland or Europe).
While fortification is proven to reduce NTDs, several influential publications in the US suggest that very high folate levels in older persons, if coupled with low vitamin B12, leads to poorer brain function and a faster rate of cognitive decline. Largely because of such fears, no country in Europe has implemented mandatory folic acid fortification, although the NTD rates have not declined in two decades and may be rising in Ireland, according to recent data.
What has the new research unveiled?
Using blood samples from over 3,700 Irish older adults aged 50 and over, the study compared cognitive health in individuals grouped by their combinations of vitamin B12 and folate blood levels. It found no evidence that having high blood levels of folate affected the risk of cognitive decline in those with low levels of vitamin B12. Moreover, having higher folate seemed to be associated with better cognitive function in these older adults.
- Cognitive performance was not worse in older people with low vitamin B12 combined with high folate (representing 1.5% of older adults in Ireland)
- Those with normal vitamin B12 levels and high folate levels (7.6% of older adults) performed better cognitively than the others
- The use of folic acid-containing supplements was uncommon, with higher rates among women than men but less than 4% overall taking supplements
Why do the findings matter?
Older adults at significant risk of deficiency
TILDA has previously reported high rates of deficiency: 1 in 8 older adults are deficient in vitamin B12, while 1 in 7 are deficient in folate. Vitamin B12 deficiency is associated with cognitive impairment and nerve damage. Older adults can have difficulty in absorbing vitamin B12 due to diminished digestive function or medications. Folate deficiency causes anaemia and is associated with heart disease, stroke, and possibly certain cancers.
Newborn babies at significant risk
Folate is critical to the healthy development of the brain and spinal cord in the growing foetus, and deficiency can cause NTDs, such as spina bifida. Consequently, public health authorities world-wide recommend that women of childbearing age consume folic acid from fortified foods and/or supplements. Voluntary food fortification is permitted in Ireland but is not effective in this regard. Ireland has one the highest rates of NTDs in Europe but does not have mandatory fortification largely because of concerns detailed above.
Lead author Deirdre O'Connor, registered Nutritionist and TILDA researcher said:
Professor Anne Molloy, senior author of the study said:
Professor Rose Anne Kenny, Principal Investigator of TILDA, said:
To view the full report, ‘Plasma concentrations of vitamin B12 and folate and global cognitive function in an older population: Cross-sectional findings from The Irish Longitudinal Study on Ageing (TILDA),’see here
The study was conducted by researchers at Trinity, in collaboration with the University of Oxford and was funded by The Atlantic Philanthropies, Irish Life, Department of Health, Health Research Board and Department of Agriculture Food and the Marine.