Folates over folic acid for fortification, says U.K. study

July 29, 2014, Newcastle upon Tyne, UK – Synthetic folic
acid, the form taken in over-the-counter folic acid supplements, is not processed by the body in the same way as natural
folates, the form found in green vegetables, indicates a U.K. study.

This can lead to unprocessed folic acid circulating in the blood stream, with unknown potential health effects.

With
the U.K. government considering adding folic acid to all bread flour, this
new finding from the Institute of Food Research (IFR) and Newcastle University
suggests the possibility of using a different folate form for
fortification and the need to better understand the implications of excess folic
acid.

Professor David Jones, dean of research and innovation in the faculty of medical sciences at
Newcastle University,
and his team were able to directly sample blood from the
hepatic portal vein of patients who had previously been fitted with a
stent, or shunt. Volunteers were fed either labelled folic acid or
labelled natural folate. The dose of folic acid and natural folate was
below that which is currently recommended for supplement use for women
who are planning a pregnancy. The hepatic portal vein carries blood from
the gut directly to the liver. This blood, and blood from the main
circulatory system, was then analyzed by the team at the IFR, which is strategically funded by the Biotechnology and Biological Sciences Research Council.

“Folic
acid fortification has been advised and adopted on the basis that the
body treats it in the same way as natural folates we get from
vegetables, but now we know that’s just not the case,” said Paul Finglas
from the IFR in a news release.

The new study clearly showed that 86 per cent of folic
acid in the hepatic portal vein is unmetabolized, while almost all of
the natural folate was converted correctly.

This contradicts
previous findings, which were based on metabolism in rats, but agrees
with work done in the late 1960s using much higher doses of labelled
folic acid in humans.

Natural folate, which we get from eating
green leafy vegetables, is absorbed and metabolised by cells lining the
gut. Folic acid is a synthetic version of folate, created in the 1940s
to be more stable and cheaper to manufacture, for use in supplements.
Women thinking of becoming pregnant are advised to take these
supplements, as low folate levels in pregnancy are associated with
neural tube defects (NTDs) such as Spina Bifida and Anencephaly. But in
the UK, many pregnancies are unplanned. This has led to recommendations
that UK flour should be fortified with folic acid, to reduce the 900
neural tube defect births in the UK every year, and the Department of
Health are now considering this.

“This work doesn’t mean that folic acid is
not safe. It suggests, however, that the assumption that it will be
automatically safe because the body can handle it is not correct,” said Jones, in the release.

Several
countries, including Canada, the United States and Australia, have introduced
mandatory folic acid fortification. This has led to a reduction in
neural tube defects of up to 46 per cent but has also seen intakes three times
higher than the recommended amount. A number of studies have flagged potential problems with
excess folic acid, including compromising the immune system, masking
vitamin B deficiency and possibly increasing the risk of some forms of
cancer. The
new findings, published in the American Journal of Clinical Nutrition, throw up new questions of how much we would be exposed to unmetabolized folic acid following mandatory fortification.

Because
of this, the scientists suggest that fortification can also be done
with the natural forms of folate. These are already licensed for use
under the names Metafolin and Quatrefolic, and for use as supplements.

See the abstract, Folic acid handling by the human gut: implications for food fortification and supplementation