Deep Dive: L-Theanine

When I first heard of L-Theanine, it seemed like one of those supplements I simply didn’t need because it wasn’t a commonly discussed product. It wasn’t like Vitamin D or Fish Oil, which I already use daily because of all the research that is touting their importance for brain, heart, and joint health.

I recently started using this supplement again in the morning with my coffee. I take it alongside Gamma-aminobutyric acid (GABA), which is a chemical that is made in the brain. These two supplements are known to help ease anxiety, stress, and reduce insomnia. Before adding these supplements, I was woman smiling while presenting somethingexperiencing a lot of anxiety around bedtime. I was unable to sleep without the help of sleep aids. My naturopath helped me out by suggesting these two products in the morning, and an extra GABA at night. Although I think the GABA helped, the L-Theanine is what I think really did the trick.

Because of my lack of sleep, I was having trouble concentrating in the morning. L-Theanine mixed with caffeine (my morning coffee) helped a lot with my mental alertness and wakefulness.

Read on to learn more about how I started supplementing with L-Theanine and how it could possibly help you. You’ll wish you heard of it earlier!

What is it?

L-theanine is an amino acid that is difficult to find in your diet. It’s not necessarily an essential amino acid or even a common non-essential amino acid. So why is it so popular and why is there even a market for it?

It’s known for its anti-anxiety and anti-stress benefits! With less stress, sleep also becomes easier, reducing your chances of insomnia. 

As I mentioned with GABA above, L-Theanine impacts nerve impulses in the brain, which in turn release neurotransmitters like GABA, which is why I think L-theanine was the major contributor to my lack of anxiety. L-theanine is known as an anxiolytic, which reduces anxiety due to its sedative effect on the body and mind (without all the drowsiness!).

This unique amino acid is not used to form proteins, unlike other amino acids like L-carnitine, leucine, lycine, or tryptophan. It’s not used to make enzymes, either. 


The list is ongoing. Most of you reading this blog may actually start to consider adding L-theanine to your morning routine.

  • Anxiety, depression, and mood-related disorders: improve your ability to deal with stress without lethargy. This means you’ll be relaxed, but not so relaxed that you will fall asleep. Theanine may increase alpha brain waves (α-waves), which are associated with a state of “wakefulman studying from a book relaxation,” selective attention mechanisms, arousal, and mental alertness*
  • Insomnia or trouble falling/staying asleep: Why take L-theanine alone? Melatonin is a great addition to this supplement to help reduce stress and help with sleep quality. But be careful with the dose. If you take more than 600mg of L-theanine, you may have opposite effects.
  • Cognitive loss, like dementia or Alzheimers: L-theanine helps protect the brain by preventing excessive glutamate stimulation of the brain cells, which is believed to be linked to neurodegenerative disorders, stroke, and schizophrenia! L-theanine offers neuroprotection for your aging brain!
  • High blood pressure: In stressful events, your blood pressure will naturally spike. L-theanine can help to prevent this by regulating nitric oxide. Adequate production of nitric oxide can help to protect against artery-blocking clots or obstructions, heart attacks, stroke, and other cardiovascular problems. Even 12-24 hours after a stroke, taking L-theanine may help protect brain black board with lightbulb on top and idea bubblescells and reduce damage caused by the stroke.
  • Poor attention span: Theanine helps control fear responses and memory because it impacts two important areas of the brain – the amygdala and hippocampus. Improve your focus with L-theanine and caffeine together (200mg of each). You may notice that you feel more focused without the wired or jittery feeling.

L-theanine is also said to be helpful in reducing the symptoms of post-traumatic stress disorder (PTSD) and for those with substance dependence, however, I highly recommend speaking to your doctor about how you can use this alongside other medications or treatments (therapy).

Dietary Sources

Unfortunately, there really aren’t that many dietary sources of L-theanine, which is why many people

pouring green tea

choose to supplement. 

The main sources of L-theanine in food and beverage are as follows:

  • Green tea, black tea, and certain types of mushrooms

According to Dr. Axe, here are two specific plants that provide L-theanine:

  • C. japonica and C. sasanqua — These are small shrubs that produce pink and red flowers. They are sometimes used to make tea.
  • The mushroom species called Xerocomus badius — Also called bay bolete, is a brown, edible, pored mushroom found in Europe and North America. This one contains plenty of antioxidants!

Unless you’re getting glasses upon glasses of tea in your diet, you likely aren’t consuming enough L-theanine, which is when supplementation comes in handy. The great thing is you can take it day or night, and it won’t keep you up late like caffeinated tea would. It isn’t the same as caffeine. It promotes relaxation, while caffeine promotes alertness. 

Who should take L-Theanine? 

If you read the benefits of L-theanine and could relate, I’d highly recommend trying this one out. It’s a cheap supplement that doesn’t have too many negative interactions except for those who are on antihypertensive drugs for high blood pressure. However, it’s important to keep some things in mind.

Special Precautions:

  • Those who are pregnant or breastfeeding should stay on the safe side and avoid using this product. Unfortunately, there isn’t enough reliable information to know if theanine is safe for this group.
  • Children: L-theanine is possibly safe when taken by mouth, short-term. Most studies have been conducted on males aged 8-12 years, but up to 400 mg was safely taken for up to 6 weeks.

If you are already taking medication, be careful when starting a new supplement like L-theanine. Some adverse reactions include: 

  • Headache
  • Dizziness
  • GI symptoms

Conclusiongreen powder

When it comes to dosing L-theanine, I’m going to say what I always say: Start low and go slow.

Start with the lower range of 200mg by mouth for a couple of weeks. If that feels comfortable and you don’t notice any negative side effects, feel free to add another 200mg. Some people will prefer this dose split into two, while others will take 400mg right away in the morning with their coffee.

If you have a specific condition, speak with a healthcare professional to find a dose that will work best for you.

Have you tried L-Theanine before? Did you notice a difference? 



Alexia Palmeri

Alexia Palmeri is a 28-year-old personal development enthusiast! She looks at life experiences as an opportunity to always learn and grow. Alexia is also a broadcast journalism graduate with a passion and knack for communications and media. She is always on the lookout for new trends on social media and keeps up to date with what's happening in the world. In her free time, Alexia enjoys socializing with family and loved ones, being in nature, cooking nourishing meals, and discovering new places to dine and adventure!

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