Green tea warning to pregnant women

23rd March 2005

Researchers have warned that drinking green tea in pregnancy increases the risk of the risk of neural birth defects such as spina bifida.

It is thought that one of the that one of the tea’s active ingredients, a naturally occurring polyphenol called EGCG, disables an enzyme, DHFR which is essential for making DNA and is
also implicated in neural tube defects.

Researchers at the University of Murcia in Spain (UMU)
and the John Innes Centre (JIC) in Norwich have shown that EGCG in
green tea prevents cancer cells from growing by binding to a specific
enzyme which triggers the growth of cancer cells.

Unfortunately, the same enzyme uses folic acid which
is known to reduce the incidence of neural tube defects.

Earlier studies had also discovered that green tea drunk
by women around the time of conception and in early pregnancy could
be linked with spina bifida and anencephaly, a birth defect that results
in the absence of part of the brain and skull.

The researchers said that in green tea drinkers, EGCG’s
antifolate activity would be expected to lessen the activity of the
enzyme that uses folic acid, minimising the good effects of folic
acid supplements.

Women are advised to take supplements of folic acid
because it protects against spina bifida but large amounts of green
tea could decrease its effectiveness.

Green tea has about five times as much EGCG as regular
tea, with 30-40 per cent polyphenols compared to 3-10 per cent in
black tea.

Green and black teas are the same plant processed in
a different way. Green tea is unfermented leaves while black tea is
fully fermented.This difference in processing results in more of the
polyphenols being destroyed in the black teas.

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