L-THEANINE IN FOCUSNEEDS®

L-THEANINE Summary

L-theanine is present in many plants commonly ingested and is a principal component of the effects of green and black tea. L-theanine has been demonstrated to increase the levels of several predominantly-inhibitory neurotransmitters, including GABA, glycine, serotonin, and dopamine. Randomized-controlled trials found that L-theanine likely has benefits in treating stress and anxiety. L-theanine is also often used to improve cognition and focus, an effect of tea drinking that is not solely related to the caffeine content. Thus, L-theanine is sometimes recommended for a variety of conditions including ADD/ADHD, stress/anxiety, and insomnia. Side effects are rare at usual doses used in supplementation.

The Details

What Is L-theanine?

L-theanine is a non-protein amino acid analogue of L-glutamate and L-glutamine. It is present in many plants that are frequently consumed, especially teas, as well as in some mushrooms.

What Does L-theanine Do?

L-theanine, along with caffeine, is a principal component of the effects of green and black tea. L-theanine can enter the brain and has been demonstrated to increase the levels of several predominantly-inhibitory neurotransmitters, including GABA, glycine, serotonin, and dopamine. L-theanine is similar in structure to the excitatory neurotransmitter L-glutamate, and L-theanine has a complex relationship with glutamate receptors, stimulating some while blocking others.

What Does a L-theanine Deficiency Appear As?

L-theanine is not required for humans and dietary deficiency is not known or expected.

What About L-theanine’s Use in Disease?

L-theanine has been studied for its potential ability to reduce mental and physical stress, and in this context, it is typically used as a dietary supplement. Randomized-controlled trials found L-theanine “may assist in the reduction of stress and anxiety in people exposed to stressful conditions” [PMID 31758301]. L-theanine is also often used to improve cognition and focus, an effect of tea drinking that is not solely related to the caffeine content. Thus, it is sometimes recommended for a variety of conditions including ADD/ADHD, stress/anxiety, and insomnia.

What Are the Common and/or Important Side Effects of L-theanine?

L-theanine is water-soluble and considered to be generally non-toxic. L-theanine might lower blood pressure, and thus is a potential concern in those with hypotension. However, side effects are rare at usual doses used in supplementation.