Pregnancy, 9 months during which it is necessary to take food precautions. The medical profession often prescribes food supplements to make up for possible deficiencies and to ensure good fetal development. Do the dietary precautions extend to tea consumption?
Pregnancy is a very complex biological phenomenon.
Pregnancy is the period from fertilization and implantation (formation of the embryo -> implantation in the uterus -> development of the fetus) to the birth of the baby. All these stages require the presence of specific molecules at specific times. For example, we know that vitamin B9 or folic acid is essential for the synthesis of vitamins, amino acids and for the enzymatic activity necessary for the growth of the fetus. It would seem that taking folic acid during the early stages of fetal development helps limit the development of serious malformations because it is linked to the proper development of the neural tube, an embryonic structure that will give rise to the brain and the spine, for example.
Tea polyphenols: antioxidant but also inhibitor
The polyphenols contained in tea leaves, such as catechins, are known to have an antioxidant action by capturing toxic reactive molecules like ROS. But they are also known to capture certain molecules like iron. This can lead to anemia depending on the diet and the period of tea intake.
It seems that another property of polyphenols is little described in the general press: its capacity to block the enzymatic activity of certain proteins. Our body functions thanks to chemical reactions generated by proteins called enzymes. For example, DHFR is an enzyme capable of reducing the inactive form of folic acid to an active form. Some studies have shown that the polyphenols in tea are able to inhibit DHFR activity, which reduces the intestinal absorption of folic acid and its bioavailability in the body.
In 2012, a compilation of pregnancy follow-ups of women consuming more than 3 cups of tea per day and folic acid supplements highlighted that tea may limit the action of folic acid supplementation, increasing the risk of spina bifida (spinal malformation) compared to women not consuming tea but taking folic acid.
Tea and pregnancy: a question of trimester?
The quantity of tea alone would not explain the risks of development of malformations noted in the follow-ups of pregnancy since it was already shown that the consumption of caffeine close to the thresholds advised for the pregnant women (around 200 Mg of caffeine is approximately 3 cups) would not be associated with a risk for the foetal development.
The timing of tea consumption would be the most recurrent risk factor in the literature on tea and pregnancy. In 2019, Gaskins et al. followed 15590 pregnancies and focused on women consuming more than 400 mg of caffeine (the population's maximum threshold) in the form of coffee, tea, or soda. The authors found that consuming more than 400mg of caffeine before pregnancy and before 20 weeks of pregnancy increased the risk of miscarriage by 1.11 times compared to women consuming less than 50mg of caffeine per day. However, the relationship between coffee and miscarriage appears to be stronger than that with tea because the women in this study consumed much more coffee than tea. Pregnancy disturbances, including hypertension, were observed in women consuming more than 300mg of caffeine in the form of tea. Caffeine consumption should therefore be monitored both before fertilization and during the first half of the first trimester.
There is little data regarding the second and third trimester of pregnancy, some studies suggest that too much caffeine consumption in the third trimester would retard fetal growth
The misunderstanding of pregnancy and tea begins before fertilization. In fact, tea consumption, especially above 3 cups and more than 200 to 400 mg of caffeine before pregnancy could increase fetal abnormalities. Negative effects on folic acid, increased probability of miscarriage and fetal malformations would occur during the first trimester. Finally, the data in the literature are still rather vague, but it would seem that tea can delay the growth of the fetus during the third trimester. Therefore, tea consumption should be limited during these periods of pregnancy.
Always consult a health care professional when you are pregnant and don't hesitate to ask questions about tea. This is important in relation to iron and folic acid supplements for example.