Anxiety disorders are the #1 mental health issue in the U.S., affecting 40 million adults. There's a lot that can be done for anxiety, yet less than 37% of those suffering ever receive treatment. Anxiety develops from a variety of factors, and sometimes combinations of factors, that include genetics, brain chemistry, personality, and life events (1).
If you've struggled with anxiety hopefully you understand that it's common and that you're not alone. Even major celebrities like Taylor Swift (T-Swift) who may appear to have a care-free, glamorous life on the outside have opened up when asked about stress and anxiety issues. In a recent Shape.com article T-Swift went on to mention that she started taking a L-theanine supplement, and she now swears by it. I mean if it's good enough for Tay-Tay, right?
What is Anxiety?
You may be relieved to find out you're not crazy. Well at least not that I'm aware of. Anxiety has a well-defined biologic explanation. Anxiety stems from altered fear and stress inputs to our brain and is followed by altered stress responses in our body. The fear and stress systems are closely wired together for very good reasons (to keep us alive), however when we detect a threat that really isn't life-threatening we can start to set off the alarm in safe, everyday scenarios.
Our bodies constantly work to keep things in balance. This balance is a term called homeostasis. Any time we have an alteration away from this point of balance we have a disruption, or stress. The stress response in humans involves a cascade of hormonal events that all starts in our brain. Sensory input from our organs such as our skin, eyes, ears and even a visual picture that we create in our minds in anticipation of a stressful event can start the initial response in higher brain centers. Being able to anticipate danger once again is a very good thing, as we then hopefully have time to avoid it. Physical challenges can also cause an imbalance resulting in the same stress response. When we perceive, or are made to believe that we are entering a stressful event anxiety can be triggered.
The amygdala is one of the areas of the brain involved in processing sensory input, sometimes subconsciously, and plays a key role in fear and triggering the stress. It is also central to registering the emotional significance of stressful stimuli and creating emotional memories. Because the stress response is so strong it can become "hard-wired" to be triggered by the amygdala when sensory input appears similar to past stressful events. Perceived triggers may become associated with similar sights, sounds, smells and even envisioning a similar experience can begin to prime and trigger this system (2).
When the amygdala is activated it stimulates the midbrain and brain stem which causes autonomic hyperactivity (sympathetic) that is correlated with anxiety. The sympathetic response, or 'fight or flight' response is initiated by the hypothalamic-pituitary-adrenal (HPA) axis. The HPA-axis is typically hyperactive in anxiety and depression disorders (2).
The activation of the HPA-axis is where the hormone cascade begins. The hypothalamus produces and releases corticotropin-releasing factor (CRF), which then signals the anterior portion of the pituitary gland to release adrenocorticotropic hormone (ACTH) and eventually activates the release of glucocorticoids, such as cortisol, and adrenaline (epinephrine) from the adrenal gland (cortex), which sit on top of our kidneys (3). CRF itself acts as a neurotransmitter with the central nervous system (CNS), activating autonomic, behavioral, immune and endocrine responses, while also causing anxiety, initiating depression and causing an inflammatory response which increase pain perception (4).
Cortisol also activates the locus caeruleus, which sends a powerful signal back to the amygdala using the neurotransmitter norepinephrine. The amygdala then sends out more CRF, which leads to more release of cortisol, and a vicious circle of feedback between the mind and the body results. When the amygdala is constantly stimulated it strengthens that communication to the brain, creating longer lasting effect by what's called long-term potentiation (5).
Our body has neurotransmitters to balance the excitatory and stimulating activity in the brain and spinal cord. The primary inhibitory neurotransmitter, GABA, plays a key role in the development of anxiety as GABA is decreased in the higher brain centers in those with anxiety disorders (6). Benzodiazepines are a class of drugs that enhance GABA's function in the brain and is commonly prescribed for anxiety.
What is L-Theanine and How Does it Improve Anxiety?
The amino acid L-theanine is a biologically active component of green tea, black tea, and is also found in certain mushrooms and in smaller amounts in other plants. Chemically L-theanine is very close in structure to glutamate and GABA, and has been shown to cross the bood-brain barrier (7). In human studies when taken as a supplement L-theanine has been shown to safely and effectively reduce anxiety (9). The mechanism shows that it increases alpha brain wave (calm and focused) activity in certain regions of the brain and increases the production of GABA, which then increases dopamine and serotonin and adds to the calming effect (8). In Asian countries it is commonly used to treat moderate and severe anxiety due to its calming effects and doesn't carry the side effects of drowsiness and risk of addiction like benzodiazepines and other treatments (11).
In some people medications can also be ineffective, or eventually lose the initial benefit after prolonged use. Because of this scientists have started looking into L-theanine in non-responsive patients as an alternative and adjunctive treatment. A 2019 systematic review published in journal Plant Foods for Human Nutrition evaluated the effect of pure L-theanine as nutritional supplements, on stress responses and anxiety levels in 9 human randomized controlled trials where all had a placebo control involved. The authors concluded that supplementation of 200–400 mg/day of L-theanine can reduce symptoms of stress and anxiety in people undergoing stressful conditions (9).
Another recent 2019 randomized, double-blind, placebo-controlled study published in the journal of Nutrients looked at L-theanine supplementation for four weeks in healthy individuals' stress response and cognition. Sleep, depression and anxiety surveys were used for evaluation along with the need for medication in these areas as well. Verbal reasoning and executive function tests were used for cognition. The findings suggested that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments (10). The next steps with L-theanine would be to perform larger clinical trials and directly compare it to other supplements and medications in the same population to confirm the efficacy of L-theanine. I'm looking forward to more research on this awesome nutrient.
How to Use L-Theanine
When supplementing with L-theanine always start with a high quality product. For most people experiencing stress or mild anxiety a calming effect is noted about 30 to 40 minutes after L-theanine is taken at a dose of 50 to 200 mg, and typically lasts 8 to 10 hours. Moderate anxiety symptoms often improve with a regimen of 200 mg once or twice daily. More severe anxiety symptoms may require doses up to 600 mg to 800 mg daily taken in increments of 100 mg to 200 mg spaced over the day (8,11).
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3. Shelton, C. (2004). Diagnosis and Management of Anxiety Disorders. The Journal Of The American Osteopathic Association, March 2004(104), S2-S5. Retrieved from https://jaoa.org/article.aspx?articleid=2092999
6. Goddard AW, Mason GF, Almai A, Rothman DL, Behar KL, Ognen AC, et al. Reductions in occipital cortex GABA levels in panic disorder detected with 1H-magnetic resonance spectroscopy. Arch Gen Psychiatry. 2001;58:556-561.
9. Williams, J., Everett, J., D’Cunha, N., Sergi, D., Georgousopoulou, E., & Keegan, R. et al. (2019). The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. Plant Foods For Human Nutrition, Nov. 22.
10. Hidese, Ogawa, Ota, Ishida, Yasukawa, Ozeki, & Kunugi. (2019). Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients, 11(10), 2362.