L-theanine is one of my favorite supplements for anxiety. It’s an amino acid found naturally in tea and several types of mushrooms, though the L-theanine in the majority of supplements are lab produced due to the difficulty and cost involved in isolating it from natural sources.

L-theanine modulates neurotransmitters, including GABA, serotonin, and dopamine, resulting in reduced stress, increased relaxation, and improved attention. It may be especially helpful for those who inherited two copies of the “worrier” gene variant, COMT met158, which results in greater dopamine signaling in the brain and a tendency toward anxiety or worrying. It may also lower blood pressure and improve sleep latency (time to takes to fall asleep). Side-effects from L-theanine are rare, but may include headache and drowsiness. Contraindications include high blood pressure medications, stimulant drugs, hypotension, pregnancy and lactation.

When combined with caffeine, either as a combination supplement or taken alongside caffeine containing beverages, the two potentiate the positive effects of each other resulting in greater alertness and improved physical and mental performance while reducing the side-effects associated with caffeine including heart palpitations, rebound fatigue, and sleeplessness.

Standard dosage of L-theanine is 50-200mg once or twice daily; timing of the supplement depends on the response of the individual. It helps some people sleep when taken prior to bedtime, but keeps others awake.

Disclaimer: The content herein is not intended to be a substitute for professional medical advice. It is not meant to diagnosis, cure, or treat any medical condition. Always consult a physician or other qualified healthcare provider with questions regarding a medical condition and before starting new diets and dietary supplements. Not all diets or supplements are appropriate for all people or all health conditions.


  1. I drink BCAAs in my water every morning and I’ve not heard of this. I know Amino Acids are helpful though. Perhaps I should do some more research! Thank You!!

    1. Amino acids are organic compounds that contain an amine group and a carboxyl group. There are 20 amino acids required by the human body for the synthesis of proteins, 9 of which must be obtained through diet. While L-theanine is an amino acid, it is not one required or synthesized by humans. Branch-chain amino acids (BCAAs), valine, leucine, and isoleucine, stimulate muscle protein synthesis, resulting in increased muscle growth and reduced muscle fatigue and wasting; it may also improve liver function in those with cirrhosis.

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