Reader I.Popoff had a strong warning in response to Bottom Line’s To Burn Fat, Pair Green Tea With Your Exercise: “Green tea should be avoided by pregnant women or those trying to become pregnant. It inhibits conversion of folic acid to folate, which in turn increases risk for the birth defect spina bifida. Additionally, green tea extracts should probably be avoided by everyone because of toxicity to the liver.”

Is it true? Could green tea, linked to so many health benefits ranging from cardiovascular health to preventing dementia to weight loss, actually be bad for pregnant women and green tea extracts bad for everyone?

For more information, we checked with obstetrician Shannon Clark, MD, MMS, an associate professor in the division of maternal-fetal medicine at University of Texas Medical Branch at Galveston, and with Health Insider’s medical contributor, naturopathic doctor Andrew Rubman, ND. Here’s what they said…


Adequate folate in the months before pregnancy and during the first trimester is indeed critical in reducing the likelihood of neural tube defects such as spina bifida. And it’s true that tea, particularly green tea, contains catechins, antioxidants that have an inhibitory effect on an enzyme that converts folic acid to folate, the active form that the body uses.

However, according to Dr. Clark, the most current research does not find that drinking green tea decreases levels of folate concentration in pregnant women. Additionally, any woman who is pregnant or may become pregnant should be taking a supplement that contains 400 mcg of folic acid/folate, which will further protect her. One caveat: Pregnant women should limit their caffeine intake to no more than 200 mg per day, says Dr. Clark. (There is conflicting evidence that higher levels may increase miscarriage risk.) That’s what’s in about two or three cups of green tea.

Bottom line: Green tea in moderation is safe for pregnant women.


There have been reports of liver injury and even liver failure linked to green tea extracts, says Dr. Rubman. Green tea is not a concern, he emphasizes.

The ingredient in questions is, again, catechins. In small amounts they act as antioxidants and are responsible for many of green tea’s health benefits, but in large concentrated doses, they can harm the liver. To put it in perspective, the American College of Gastroenterology recommends a daily limit of 500 milligrams (mg) of catechins. One cup of green tea may have between 50 mg and 150 mg, and in the study we reported, the subjects took either standardized green tea extract totaling only 375 mg or a placebo. In contrast, some supplements, such as those sold for weight loss, contain as much as 700 mg in a single pill—and the labels recommend taking several pills a day.

Dr. Rubman is particularly concerned about “enhanced” products—those that combine green tea extracts with other, often undisclosed, ingredients, which may be harmful on their own as well. While extracts made from whole tea leaves, consumed in doses that are consistent with normal daily use, are likely to be safer, he still favors the beverage. “The best advice is to drink brewed green tea rather than use extracts,” he says. “This practice has been followed safely by the Japanese, including pregnant and nursing women, for centuries.”

Bottom line: Skip the extracts—drink green tea instead.

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