By: Rachel Neifeld, RD, CDN
You may have considered green tea a fertility-friendly beverage as some studies have shown that it increases cervical mucus production, or perhaps you’ve replaced your morning cup of coffee for this low-caffeine alternative; but could green tea be doing more harm than good in your pre-pregnancy diet? It turns out that some of the beneficial aspects of green tea may not be applicable to women who are pregnant or trying to conceive.
This is because both green and black tea decrease the body’s ability to absorb folic acid, a very important B-vitamin crucial to a baby’s development in the beginning stages of pregnancy. Also important (especially for vegetarian moms and moms-to-be) is green tea’s affect on iron absorption. The tea has been shown to decrease the body’s ability to absorb iron from non-meat sources such as beans and tofu.
Decreased folic acid absorption has to do with the actions of the most abundant antioxidant found in green tea, EGCG. This antioxidant works in a similar way to the anti-cancer medication methotrexate, which is why green tea consumption has been shown to fight against cancer. EGCG can block an enzyme that cancer cells need to grow, called dyhydrofolate reductase (DHFR). Unfortunately, it is not desirable that DHFR is blocked during pregnancy, as this can lead to a folate deficiency. Low levels of folate, the B-vitamin needed to promote healthy development of the fetus’s nervous system, increases the risk of having a child with spina bifida or another neural tube disorder.
Favorable for pregnant women, there is less caffeine in green tea than coffee, with green tea (depending on the variety) containing about 20-50 mg of caffeine per serving while coffee usually contains about 100 mg per serving. Women may want to avoid green tea while they are trying to conceive and during the first trimester of pregnancy while the fetus’s neural tube is developing. After this point, it’s safe to consume one to two cups of the tea per day, preferably in between meals as to minimize any disturbance in iron and folic acid absorption from foods. And remember, when it comes to caffeine consumption during pregnancy, coffee is not off limits. It’s safe to consume up to 200 mg of caffeine during pregnancy which is equal to one 8-12-ounce cup of coffee (depending on the variety) or four 8-ounce cups of green or black tea each day.