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Warning for Pregnant Women Who Drink Green Tea

Warning for Pregnant Women Who Drink Green Tea

Though the popularity of green tea is still predominantly in Asian countries, its following is growing in North America.  Green tea itself contains antioxidants and polyphenols, in particular, such as catechins which have a number of potential health benefits including weight loss and promoting cardiovascular health [health benefits of green tea].

Folate and Pregnancy

Folate is a water-soluble B Vitamin which is of particular importance for pregnant women to prevent the occurrence of neural tube defects, preeclampsia, and intrauterine growth retardation.  As such the recommended daily intake of folate is twice as high for pregnant women (440 micrograms /day)

Deficiencies of folic acid have also been linked to conditions such as depression, cardiovascular disease, anemia, and growth retardation.

Green Tea and Folate

Previous research found that green tea interferes with folate metabolism.  Specifically, the catechin, (–)-epigallocatechin gallate (EGCG), interferes with the enzyme dihydrofolate reductase which prevents folate from being reduced to its active form.

Green tea / Oolong tea and Folate during Pregnancy?

A recent study published in the journal, Bioscience Trends, found that high consumption of green tea or oolong tea consumption is associated with low serum folate levels during pregnancy [1].  Oolong tea is a traditional Chinese tea that’s typically served at Chinese restaurants.

The cross-sectional study was conducted by researchers at the University of Tokyo and included 254 women recruited from a prenatal clinical.  The association between green tea or oolong tea consumption and lower levels of folate were present even when confounding factors such as dietary folate intake, folate supplements, and multivitamins were adjusted for.

Bottom Line on Green Tea in Pregnancy:

This and previous research suggests that consuming green or oolong tea is associated with lower serum folate levels in pregnant women.  Given the potential adverse effects of folate deficiency on fetal malformations such as neural tube defects, pregnant women should restrict their intake of these teas during pregnancy.

This research suggests that trying to offset the effect of green tea consumption by supplementation with vitamins or dietary intake of folate may not be effective. Pregnant women may incorrectly assume that green tea is a healthy option given its other known salutary effects.


  1. Biosci Trends. 2010 Oct;4(5):225-30.


  • Dawn

    A timely warning as green tea becomes more popular in Western countries. This was new to me - I was aware only of the positive benefits of green tea.

    • Jarret

      Dawn, I wasn't really aware of this issue with green tea myself until 2008. It seems like it's an important issue for pregnant women to consider.

  • Patricia

    Very interesting study Jarret. That's really important to know as green tea has been seen as a healthy drink and is increasingly seen as a healthy alternative to drinking coffee here in Oz. Just goes to show we need to research these things thoroughly to find out all the facts. Thanks for sharing and will definitely be telling my younger friends about this. Patricia Perth Australia

  • Stacey @770sportshop

    Everything in moderation for EVERYONE. But definitely, women must limit the amount of green tea they consume during pregnancy. Thanks for posting this piece, there is so much buzz about the benefits of green tea and it's important to know the potential dangers of herbs as well.

    • Jarret Morrow, M.D.

      Hi Stacey, thanks for the feedback. I agree that it's important for people to be aware that natural doesn't always mean safe. In the case of green tea, there are numerous potential health benefits associated with drinking it, but pregnant women should be cautious.

  • Bryan

    Hmm interesting study, never thought green tea could interfere with folate metabolism. I wonder what was the reason for doing the study in the first place. A case report of someone having trouble with their pregnancy after drinking green/oolong tea?

  • Eric Graham

    Hi Jarret, Since green tea is primarily used for weight loss then it can actually cause some problems to pregnant women such as given the potential adverse effects of folate deficiency on fetal malformations such as neural tube defects. This is actually an eye opening article especially for those first time soon to be moms. Great article!

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