The Details

What Is L-theanine? L-theanine is a non-protein amino acid analogue of L-glutamate and L-glutamine, and is found primarily in particular plants, especially teas, but also in some mushrooms.

What Does L-theanine Do? L-theanine is present in many plants commonly ingested, and 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 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 does not exist.

What About L-theanine’s Use? 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. A randomized-controlled trial found L-theanine “may assist in the reduction of stress… in people exposed to stressful conditions.”* [] L-theanine is also often used to support cognition and focus*, an effect of tea drinking that is not solely related to the caffeine content.

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.

Is There Any Laboratory Testing for L-theanine Deficiency? Laboratory testing is neither available nor clinically useful.

Why is L-theanine Used in CalmNeeds®?


L-theanine is added to CalmNeeds® as it generally promotes relaxation without drowsiness*.


*These statements have not been evaluated by the U.S. Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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