The research indicates that simultaneous supplementation could improve blood folate levels, and could have implications for folic acid fortification, with the signs indicating that it will be introduced in the UK soon.
An announcement is expected within the next month or so concerning fortification in Ireland, and similar measure under scrutiny in Australia.
"Administration of a physiological dose of [6S]-5-methyltetrahydrofolate with L-ascorbic acid significantly improved the measured serum folate response in folate saturated healthy men," wrote the researchers, led by Professor Ann Van Loey, in the European Journal of Clinical Nutrition .
Deficiency of folic acid, a B vitamin that occurs naturally in foods such as grains, lentils, chick peas and green leafy vegetables, in the very early stages of pregnancy can lead to neutral tube defect, such as spina bifida, in the infant.
Mandatory fortification of grain products with folic acid in North America since 1998 has led to a significant reduction in NTD incidence.
Although the UK and Ireland have been seriously looking into it, no European country has introduced parallel measures so far.
A team of researchers from Trinity College Dublin reported in March this year that US levels of folic acid could safely be doubled (BMC Public Health).
Moreover, scientists at the University of Bonn in Germany reported last year that the folic acid derivative, [6S]-5-methyltetrahydrofolate ([6S]-5-MTHF), is even more bioavailable when given as supplements than folic acid, and could be an alternative for the primary prevention of neural tube defects ( American Journal of Clinical Nutrition , Vol. 84, pp.
156-161).
The new study, from the Katholieke Universiteit Leuven, investigated the effect of simultaneous administration of [6S]-5-MTHF and vitamin C on the folate status of nine healthy men.
Four interventions were tested: placebo; [6S]-5-MTHF only (343 g);
[6S]-5-MTHF (343 g) plus vitamin C (289.4 mg); and (4) [6S]-5-MTHF (343 g) plus vitamin C (973.8 mg).
Van Loey and co-workers report that 30 minutes after administration, blood folate concentrations rose significantly compared to baseline measurements.
These elevated values were maintained for six hours in the two vitamin C groups, compared to only four hours for the [6S]-5-MTHF only group.
Maximum values were measured between 30 and 90 minutes after supplementation.
"When [6S]-5-MTHF was concurrently administered with 289.4 or 973.8 mg
[vitamin C], the total serum folate response… was significantly improved (46.54.0 and 53.04.0 versus 34.33.8 h nmol/l,)," wrote the researchers.
However, no statistically significant differences were observed in folate response as a function of the dose of vitamin C, they added.
Further research with a larger and longer scale human intervention trial is needed to fully explore the implications of these results.
In the case against folic acid fortification, fears have been raised that high levels may mask detection of vitamin B12 deficiency, especially in the elderly.
If this deficiency is not identified it can eventually lead to dementia.
According to the UK FSA's Scientific Advisory Committee on Nutrition, folic acid intakes of one mg/day would not be expected to mask vitamin B12 deficiency, and most adverse effects in relation to vitamin B12 deficiency have been reported at doses at or above 5mg/day.
Source: European Journal of Clinical Nutrition Published online ahead of print, 11 July 2007; doi: 10.1038/sj.ejcn.1602840 "L-ascorbic acid improves the serum folate response to an oral dose of [6S]-5-methyltetrahydrofolic acid in healthy men" Authors: P.H.C.J Verlinde, I. Oey, M.E. Hendrickx, A.M. Van Loey and E.H.M. Temme