Is L-Theanine Safe During Pregnancy?

Is L-Theanine Safe During Pregnancy?

Pregnancy is a time of heightened awareness about what goes into your body. With the popularity of supplements like L-Theanine rising, many expecting mothers wonder if it's safe for them and their babies.

This blog aims to identify if L-Theanine is safe during pregnancy, exploring its nature, sources, and benefits. It will provide you with the information you need to make informed decisions about L-Theanine and its consumption during pregnancy.

What is L-Theanine?

L-Theanine is an amino acid that's primarily found in green and black tea and certain types of mushrooms. It's known for its antioxidant properties and its ability to promote relaxation. Structurally, it's related to glutamic acid, a neurotransmitter in the brain, and it's known to increase dopamine levels. The small intestine absorbs this compound and crosses the blood-brain barrier, which allows it to have direct effects on the brain.

The amino acid is often used to reduce stress and anxiety but has also recently gained attention for its potential cognitive benefits, including improved focus and attention.

Sources of L-Theanine

  • Green tea leaves
  • Black tea leaves
  • White tea leaves
  • Oolong tea leaves
  • Matcha powder
  • Some varieties of mushrooms, such as Boletus badius
  • Certain species of Camellia
  • Dietary supplements specifically containing L-Theanine

Benefits of L-Theanine

An abundance of research has noted the positive effects of L-Theanine on health and well-being in the general population. L-Theanine has been shown to:

  • Promote relaxation and reduce stress
  • Enhance cognitive function and mental clarity
  • Improve focus, attention, and concentration
  • Support better sleep quality and duration
  • Help regulate mood and alleviate anxiety
  • Enhance alpha brain wave activity associated with relaxation and creativity
  • Support cardiovascular health by helping regulate blood pressure
  • Exhibit antioxidant properties, protecting cells from damage caused by free radicals

However, it's important to note that there is a lack of comprehensive studies specifically examining the effects of L-Theanine supplementation during pregnancy. Most studies on L-Theanine focus on its effects in non-pregnant adults or animal models.

L-Theanine and Pregnancy

Despite its availability in health food stores and its presence in various teas, the safety of L-Theanine during pregnancy remains a topic of debate due to insufficient research on its impact on fetal development and maternal health. The compound's ability to cross the blood-brain barrier and influence neurotransmitter levels, such as dopamine, raises questions about its potential impact.

One study by El-Borm and Abd El-Gaber (2021) examined the prenatal exposure of green tea extract (a source of L-Theanine) on the development of the central nervous system of 20-day-old rat fetuses. They found that the administration of green tea extract during induced various histological, immunohistochemical, and ultrastructural degenerative changes in the cerebral cortex, cerebellum, and spinal cord of 20-day-old rat fetuses. The body weight of both the mothers and fetuses was also significantly decreased. These changes were directly proportional to increasing the green tea extract dose.

While these findings are in rats and not directly applicable to humans, they underscore the importance of caution regarding L-Theanine supplementation during pregnancy.

Additionally, the presence of caffeine in nonherbal teas, even in decaffeinated versions, poses additional concerns for pregnant women, as caffeine can cross the placenta and potentially affect fetal development.

For example, a study by Gleason et al. (2022) found that exposure to increasing levels of caffeine, even in low amounts, was associated with shorter stature in early childhood. The reductions were apparent even with levels of caffeine consumption below clinically recommended guidelines of less than 200 mg per day. Given the uncertainties and potential risks, it's advisable for pregnant women to avoid green teas and L-Theanine supplementation.

Consuming L-Theanine in the form of tea extracts or supplements can also lead to adverse effects, such as gastrointestinal problems, headaches, and dizziness. These side effects could potentially complicate a pregnancy.

Recommended Dietary Practices During Pregnancy

During pregnancy, it's crucial to prioritize nutrition and dietary practices that promote both maternal and fetal health. A balanced diet rich in fruits, vegetables, lean proteins, and whole grains is highly recommended. These foods provide essential nutrients like folic acid, iron, calcium, and protein, which are vital for the baby's development.

In addition to a balanced diet, it's also recommended to take prenatal vitamins. These supplements are specially formulated to meet the increased nutritional needs during pregnancy. They contain higher levels of certain nutrients that pregnant women need in larger quantities, such as folic acid and iron.

Hydration is another key aspect of dietary practices during pregnancy. Drinking plenty of water helps maintain amniotic fluid levels and aids in the transportation of nutrients to the baby. It also helps prevent common pregnancy complications like constipation and hemorrhoids.

While it's important to focus on what to include in your diet, it's equally important to know what to avoid. Certain foods and supplements, like L-Theanine, should be avoided due to insufficient research on their safety during pregnancy. Always consult your physician before introducing any new supplement into your diet.

Recommended Teas During Pregnancy

We recommend opting for herbal teas during pregnancy, which are typically caffeine-free and offer a variety of health benefits.

Peppermint tea, for instance, is known for its ability to alleviate morning sickness and digestive issues, common complaints during pregnancy. Raspberry leaf tea is another popular choice, often recommended for its potential to strengthen the uterus in preparation for labor. However, it's best to avoid this tea in the first trimester due to potential uterine contractions.

Chamomile tea, renowned for its calming properties, can help manage stress and promote better sleep, both of which are beneficial for expectant mothers. However, it's important to note that some people may be allergic to chamomile, so it's best to try a small amount first.

Lemon balm tea is another safe option, known for its soothing effects on the nervous system and potential to reduce anxiety and promote sleep. It's also rich in antioxidants, which are beneficial for overall health.

Is L-Theanine Safe During Pregnancy: A Final Review

The safety of L-Theanine during pregnancy remains uncertain due to limited scientific research on its effects, specifically in pregnant women. While L-Theanine is generally regarded as safe for the general population, its potential impact on fetal development and maternal health raises concerns that cannot be overlooked.

Studies on prenatal exposure to substances containing L-Theanine, such as green tea extract, suggest possible adverse effects on fetal development, highlighting the need for caution. Additionally, the presence of caffeine in nonherbal teas further complicates the issue, as caffeine consumption during pregnancy has been associated with adverse outcomes.

Given these uncertainties and potential risks, it's advisable for pregnant women to err on the side of caution and avoid L-Theanine supplementation, particularly in concentrated forms such as supplements or extracts. Instead, opting for herbal teas that are caffeine-free and have a long history of safe use during pregnancy may be a safer alternative.

Ultimately, prioritizing a balanced diet rich in essential nutrients, staying hydrated, and consulting with a healthcare provider for personalized recommendations are key practices for promoting maternal and fetal health during pregnancy. While L-Theanine may offer benefits for non-pregnant individuals, its safety during pregnancy remains an area that requires further research and consideration.

Researched and reviewed by Dr Elena Seranova, Ph.D.

Dr Seranova holds a master's degree in Translational Neuroscience from the University of Sheffield, UK, and a Ph.D in Stem Cell Biology and Autophagy from the University of Birmingham, UK. She is a published author in multiple peer-reviewed journals, including Cell Reports and Developmental Cell.


El-Borm, H., & Abd El-Gaber, A. Effect of prenatal exposure of green tea extract on the developing central nervous system of rat fetuses; histological, immune-histochemical and ultrastructural studies. Saudi Journal of Biological Sciences. (2021) 

Gleason et al. Association of Maternal Caffeine Consumption During Pregnancy With Child Growth. JAMA Network. (2022)

Leave a comment

Please note, comments must be approved before they are published