This Supplement Pairing May Help Reduce Stress and Anxiety

The trend of “stacking” supplements—combining them to amplify health benefits—has been gaining popularity in the wellness community. Some have suggested combining GABA and L-theanine, two supplements marketed for stress and anxiety management, may offer a stronger calming effect.

L-theanine, in doses ranging from 200 to 400 mg per day, has shown promise in reducing stress and anxiety. Similarly, a few small studies have indicated that GABA-fortified oolong tea may help ease stress. However, concrete data on the benefits and effectiveness of taking these supplements together remain limited.

“There have not been studies in humans to provide guidance on efficacy or dosing for ‘stacking’ of L-theanine and GABA,” Ana Lupu, PharmD, an ambulatory clinical pharmacist at UPMC Western Psychiatric Hospital, told Verywell in an email.

Animal research, like a 2019 study on rats, found that a combination of GABA and L-theanine improved sleep. But whether this effect translates to humans—and if it could help with anxiety—remains uncertain.

“Stress and sleep management are complex topics. Current evidence suggests that L-theanine may be a helpful adjunct for anxiety management when combined with lifestyle changes. In contrast, the data supporting GABA for stress relief is less compelling; its use should be primarily focused on aiding sleep,” Lupu said.

Before trying GABA and L-theanine together, here’s what you should know.

Can Taking GABA and L-Theanine Together Reduce Stress?

The human body naturally produces GABA, a chemical that blocks certain messages in the brain and calms the body, but studies have found mixed results for using GABA supplementation.

“GABA is active in the central nervous system, but we’re not actually sure if much of that supplement will actually cross the blood-brain barrier and get into that central nervous system,” said Jamie Alan, RPh, PharmD, PhD, an associate professor of pharmacology and toxicology at Michigan State University College of Human Medicine.

In other words, GABA supplements might not be effective if they can’t travel to the necessary areas of the body. While more research is needed, current evidence offers limited support for the benefits of GABA supplements in reducing stress or improving sleep.

L-theanine, on the other hand, is an amino acid found in green tea and mushrooms that can cross the blood-brain barrier. Existing studies show that L-theanine may improve memory and attention.Yet, like most supplements, more research is needed to fully understand its impact on humans.

“There could be some benefit to trying L-theanine, but adding GABA on top of that, the benefit is unlikely,” Alan added.

Is It Safe to Stack L-Theanine and GABA?

Studies have not identified any serious side effects from GABA supplements, but taking more than 300 mg at a time may cause headaches, drowsiness, or abdominal discomfort. Additionally, GABA supplements may lower blood pressure, posing potential risks for people on blood pressure medication.

L-theanine is generally considered safe, but it may increase drowsiness when combined with certain sleep-aid medications and can also interact with blood pressure medications.

Neither supplement is likely safe for people who are pregnant or breastfeeding.

The Food and Drug Administration (FDA) does not test the safety or effectiveness of supplements, including GABA and L-theanine, before they are marketed. Third-party sites like ConsumerLab provide independent testing that can help you make a decision on the right supplements.

Researchers have not studied the long-term effects of stacking GABA and L-theanine.

“Short-term or intermittent co-administration appears to be safe,” Lupu said, adding that it’s important to consult a healthcare provider first, given the potential risks associated with these supplements.