This combination of supplements may help reduce stress and anxiety.

The trend of “bundling” supplements—combining them to enhance health benefits—is gaining popularity in the wellness community. Some suggest that combining GABA and L-theanine, two supplements marketed for managing stress and anxiety, may provide a stronger calming effect.

L-theanine in doses of 200 to 400 mg per day has shown promising results in reducing stress and anxiety. Likewise, several small studies have shown that oolong tea enriched with GABA may help relieve stress. However, specific data on the benefits and effectiveness of taking these supplements together remains limited.

“There have been no human studies that can provide efficacy or dosage recommendations for L-theanine and GABA ‘bundling,’” Ana Lupu, PharmD, an outpatient clinical pharmacist at UPMC Western Psychiatric Hospital, told Verywell via email.

Animal studies, such as a 2019 rat study, have shown that the combination of GABA and L-theanine improves sleep. But whether this effect generalizes to people and whether it can help manage anxiety remains unclear.

“Stress and sleep management are complex topics. Evidence suggests that L-theanine may be a useful supplement for anxiety management when combined with lifestyle changes. In contrast, the evidence supporting GABA’s ability to relieve stress is less compelling; its use should primarily be aimed at improving sleep,” Lupu said.

Before you try GABA and L-theanine together, here’s what you need to know.

Can taking GABA and L-theanine together reduce stress?

The human body naturally produces GABA, a chemical that blocks certain signals in the brain and calms the body, but research has shown mixed results with GABA supplements.

“GABA is active in the central nervous system, but we’re actually not sure whether much of this supplement will actually cross the blood-brain barrier and enter that central nervous system,” he said. Jamie Alan, PharmD, PharmD, Ph.D.Assistant Professor, Department of Pharmacology and Toxicology, College of Medicine, Michigan State University.

In other words, GABA supplements may not be effective if they cannot reach the required areas of the body. Although more research is needed, available 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 research suggests that L-theanine may improve memory and attention.However, as with most supplements, more research is needed to fully understand its effects on humans.

“There may be some benefit from L-theanine, but if you add GABA to it, the benefit is unlikely,” Alan added.

Is it safe to combine L-theanine and GABA?

Studies have not found 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 a potential risk for people taking blood pressure medications.

L-theanine is generally considered safe, but it may increase drowsiness when combined with some sleeping pills and may also interact with blood pressure medications.

Neither supplement is likely safe for pregnant or breastfeeding people.

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

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

“Short-term or intermittent co-use appears to be safe,” Lupu said, adding that it is important to consult with a physician first given the potential risks associated with these supplements.