What You Need to Know About L-Theanine

Dr. Morgan Camp M.D.


L-Theanine is not produced, or even essential for the human body. But it may induce a variety of positive health effects when consumed on its own, or with other medicines. L-Theanine may affect certain chemicals within the brain, and is definitely worth knowing a little something about.

What is L-Theanine? L-Theanine is an amino acid that is found in green and black tea leaves, and to a lesser extent in some types of mushrooms. 

A natural compound derived from those plants and fungi, L-Theanine is not produced, or even essential for the human body. But it may induce a variety of positive health effects when consumed on its own, or with other medicines. 

With particularly high concentrations found in green tea leaves, L-Theanine may affect certain chemicals within the brain including:

  • Serotonin: Helps influence mood, sleep and emotions, and may play a role in appetite and digestion. It is sometimes known as the ‘happy chemical’ and is mainly present in the brain, bowels, and blood platelets. (1) 
  • Dopamine: A chemical produced by the brain and is released during periods of pleasure such as exercise, sex, positive social interactions, and when we consume our favorite foods. Dopamine can also affect sleep, memory, blood flow, and digestion. (2) 
  • Cortisol: A hormone made by the adrenal glands, cortisol helps the body to deal with stressful situations and plays an important role in maintaining and regulating blood pressure, blood sugar levels, fights infections, and helps control metabolism. (3)  

What Are The Health Rewards Of L-Theanine? 

With more and more research being conducted into L-Theanine, scientists are increasingly aware of how it could assist a healthy mind and body. The distinctive amino acid contained within tea shows evidence that it can relax the mind without causing drowsiness, and can play a critical role in mental alertness, attention, and arousal too. (4)  

Effects and benefits of L-Theanine can also include:

  • Better sleep. Analysis has shown that L-Theanine may help people to relax before going to bed, enabling easier sleep, and inducing a deeper sleep. A 2018 study over an 8-10 week period, has shown encouraging results in the treatment of sleep disturbance in patients suffering from anxiety and depression. (5)
  • Relaxation. It is said that tea is the most consumed beverage in the world after water. As well as maintaining levels of hydration, drinking tea is often used to help people relax. Levels of L-Theanine in green and black tea may help with those feelings of relaxation. Tea is also rich in flavonoids and their antioxidant effect can fight against the free radicals linked to aging and disease. (6)
  • Anxiety and stress relief. Various randomized trials have found L-Theanine reduces feelings of stress and anxiety during difficult situations. As stated above, it has also been shown increased relaxation without causing drowsiness. (7) 
  • Weight loss. As part of a healthy balanced diet, L-Theanine in green tea may create a savory taste known as umami flavor. Researchers have suggested umami flavors may help suppress appetite, aiding in weight loss. (8)
  • Improved attention and focus. A study in 2013 found moderate levels of combined L-Theanine and caffeine led to increased attention and focus, along with lower levels of tiredness in general. Black tea contains higher levels of caffeine than green tea,
    but lower levels of L-Theanine. (9) 
  • Fortifies the immune system. L-Theanine may boost immune function.
    Studies suggest, in elderly patients displaying low serum protein, supplements of L-Theanine (280 mg) and cysteine (700 mg) enhance the primary antibody response to the influenza vaccine in elderly participants. Cysteine is an amino acid found in poultry, eggs, beef and whole grains. (10)
  • Lowering blood pressure. With anti-anxiety and stress benefits, L-Theanine may help to lower heart rate and blood pressure levels. Increased blood pressure is linked to several health problems such as heart attack and stroke.

How To Find L-Theanine 

As we now know, L-Theanine is found in green and black tea leaves. As tea has been shown to be among the most frequently and widely consumed drinks in the world, this is the most popular method of consuming L-Theanine.

Matcha green tea has been consumed for many centuries, mainly in Asia. It is a finely ground powder of specially grown and processed green tea leaves gaining popularity the world over. The green tea plants used for matcha are shade-grown for three to four weeks before harvest after which the stems and veins are removed during processing. Grown in shady conditions, the plant Camellia sinensis produces more L-Theanine and caffeine than traditional green tea. The powdered form of matcha is consumed differently from tea leaves or tea bags, as it is added directly to liquid, typically water or milk. (11) 

Bay Bolete is an edible type of chestnut-colored mushroom that grows in coniferous and deciduous forests where the floor is more acidic. It contains smaller amounts of L-Theanine than green or black tea.

L-Theanine has also been used as an additive in foods such as gum and chocolate. Trials have suggested the potential for supplementation of L-Theanine in foods such as bread, juices, non-herbal teas, sporting beverages, specialty bottled water, and even mints. (12)  

Supplements of L-Theanine are available in pill or tablet form in many health-food or drugstores.

One product rich in L-Theanine is Be Serene Instant Relief, a highly effective formula designed to reduce anxiety, stress, and nervousness. Topically applied to the wrists or temples, Be Serene Instant Relief acts quickly to cut through panic and worry and can help induce a better night’s sleep. Made with 100% natural, potent-rich ingredients including California poppy, mulungu, Albizia Supreme, and Gaba, Instant Relief is safe and easy to use.

L-Theanine – A Conclusion 

In a world full of anxiety, stress, and the challenges of modern living, L-Theanine can play an important role in our health and well-being. Whether you get it from drinking tea, or as an additive in food, taken as a herbal supplement on its own, or with a combination of extracts from other medicinal herbs, L-Theanine is a proud member of nature’s “exclusive medicines” club. 

Although generally safe to use and readily available, always read labels and consult with a herbalist or medical practitioner before use.
Women who are breastfeeding should not drink large amounts of tea to increase levels of L-Theanine as over-caffeinating may be possible. Similarly, this may also cause nausea, upset stomach, and irritability. (13)  

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About Dr. Morgan Camp M.D.

Dr. Morgan is an expert in Functional and Integrative Medicine with a Strong Emphasis in stress related illnesses like anxiety and insomnia. In addition to his 20 years of work in Functional Medicine, he has expanded his practice to include work on the deeper aspects of our being that point to the root cause of our illnesses working with Mind Body Wellness, Energy Medicine, and Healing with Consciousness.
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