Pregnant women would be wise to limit the amount
of green tea they drink during pregnancy, and should be careful about taking
any green tea supplements. Green tea is rich in antioxidants, and has a host
of health benefits relating to dental health, blood sugar levels, cholesterol,
and weight loss. But researchers have found, whilst examining the active
constituent of green tea, the epigallocatechins, or EGCG for short, that it
may affect the way the body uses folate. Folate is important for pregnant
women as it prevents neural tube birth defects in babies.
The problem of green tea during pregnancy is that the EGCG molecules are
structurally similar to a compound called methotrexate. Methotrexate is able
to kill cancer cells by chemically bonding with an enzyme in the body called
enzyme dihydrofolate reductase (DHFR). Healthy people have this enzyme also -
it is part of what is called the folate pathway, which is the pathway, or
steps, the body takes to transform nutrients like folate into something that
can be used to support its normal functions.
But this chemical similarity means that the EGCG in green tea also binds with
the enzyme DHFR, and when it does this, it inactivates this enzyme. When this
enzyme is inactivated, the ability of the body to use folate is going to be
affected. How much green tea is able to be consumed, or precisely how much
folate absorption is affected, is unclear. Though the research article did say
that drinking 2 cups of green tea a day can stop cancer cells (which is what
methotrexate is targeting) from growing.
The good news on caffeine drank during pregnancy, from coffee and tea, is that
a moderate amount is fine. Two studies, one by Danish scientists who
interviewed more than 88,000 pregnant women, and the other by the Yale
University School of Medicine, had similar findings on caffeine during
pregnancy.
The concerns over caffeine were that it would lead to low birth weight or
miscarriage. And this is still true of a very high daily intake of coffee. The
Yale team found that drinking about 600mg of caffeine a day, which is about 6
cups of coffee, would reduce birth weight to levels that were clinically
significant. The rate at which birth weight was reduced was established at
being 28 grams per 100 mg, or 1 cup, of coffee per day. But they emphasized
that this would not be significant for moderate caffeine consumption.
The Danish study found that drinking 8 cups or more of coffee per day (this
would be about 16 cups or more of tea), would increase the chances of
miscarriage, or stillbirth, by 60% compared to women who did not drink
caffeine. They also found that moderate coffee or tea drinking did not pose
significant risks. For those drinking half a cup to 3 cups of coffee a day,
the risk of fetal death was 3% higher compared to non-caffeine drinkers. And
for those drinking 4 to 7 cups of coffee a day, the risk increases to 33%. One
cup of coffee equals about 2 cups of tea when comparing caffeine levels. The
recommended amount of coffee drunk is up to 3 cups daily, or 6 cups of tea, by
the UK food agency.
Read more @
http://www.buzzle.com/editorials/1-24-2006-87222.asp
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