L-Theanine for Anxiety: Pros and Cons

By Caitlin Bray

L-Theanine for Anxiety: Pros and Cons

In any conversation about natural products that can help fight anxiety, L-Theanine is one of the most frequently brought up… and for good reason! 

L-Theanine is a natural and efficient way to promote both your mind and your body to a state of calm and relaxation, even when you’re feeling overwhelmed or uneasy. 

But, like everything in life, L-Theanine comes with its own unique set of pros and cons. Knowing what they are can help you make a more informed choice if the supplement is right for you.

What is L-Theanine?

L-Theanine is an amino acid, one that is not able to be produced naturally by the body (these are called “essential” amino acids, and must always be supplemented). It is water soluble and is found mostly in tea leaves, both black and green. It can also be found in certain types of mushrooms, as well, like Bay Bolates. 

While many other supplements that we know to be effective have been used for medicinal purposes for centuries, L-Theanine was only discovered in 1949 by Japanese scientists. In addition, when it was first discovered, it wasn’t because those scientists were looking for a new medicinal supplement. Those scientists were actually looking for a source of umami, which is an additional flavor (besides spicy, sweet, salty, sour, and bitter) that has been described as rich and savory. 

A fun fact about L-Theanine is that it may be able to literally change our perception of how things taste, especially when it is consumed in tea form. This is especially true when it comes to bitter foods, like grapefruit or dark chocolate. 

What Are the Reported Benefits of L-Theanine?

L-Theanine is particularly useful in promoting relaxation, increasing focus, and supporting healthy sleep patterns.* 

While we’ll get into the science behind how and why L-Theanine works in a minute, let’s look a little deeper at some of those reported benefits. 

When it comes to reducing feelings of anxiousness and stress, L-Theanine really shines. 

Many people report that the amino acid helped them to feel calm yet wakeful at the same time. L-Theanine also affects some of the physical effects of being uneasy, like lowering blood pressure and decreasing heart rate.* 

Supplementing with L-Theanine can also help to improve sleep.* Whether this is because it helps naturally calm you so that sleep comes easier, or whether getting better sleep helps decrease uneasiness is not 100% clear. What is clear is that people supplementing with L-Theanine both fall and stay asleep easier.

A lesser known and discussed benefit of L-Theanine is also the way it can assist with weight management in conjunction with a healthy diet and lifestyle.* While more research still needs to be done, it may have the potential to promote healthy metabolism.*

How Does L-Theanine Work?

This seemingly magic amino acid works by promoting multiple, helpful changes to the way that the brain works. 

One of those changes involves promoting healthy levels of GABA in the brain,* as well as a few other calming chemicals, like serotonin and dopamine. Each of these chemicals is considered a neurotransmitter, which, in its most basic sense, helps to send messages back and forth between neurons. 

When functioning appropriately, these neurotransmitters help regulate our emotions, help balance mood, aid in concentration, and help promote alertness and healthy sleep. With all the different functions they support, it’s no wonder that having healthy levels of these neurotransmitters results in a happier, healthier you!

In addition to promoting healthy levels of GABA, serotonin, and dopamine, L-Theanine also helps to support healthy stress management in the brain.* This helps to protect brain cells from damage caused by high levels of stress that can cause an increase in cortisol levels. 

L-Theanine also is able to enhance the brain waves in a way that can cause them to revert to an “alpha” wave pattern.* There are four different brain wave patterns - beta, alpha, theta, and delta. 

  • Beta wave patterns are what are seen when we are fully awake and conscious. 
  • Delta wave patterns are seen when someone is fully unconscious. 
  • Alpha waves, on the other hand, are the waves that are seen when we are completely relaxed, in both body and mind. This wave pattern, also known as wakeful relaxation, is also associated with an increase in the production of serotonin. 

Are There Any Compatible Supplements?

While L-Theanine is a pretty amazing supplement all on its own, it works even better in combination with a few other supplements. 

A great example of that is GABA. One of the ways that L-Theanine works, as we’ve learned, is that it helps promote healthy GABA concentrations available for use in the brain.* If you use a supplement that has both L-Theanine and GABA, you’re starting out even further ahead! GABA also helps promote better, longer sleep.* Together, GABA and L-Theanine are a match made in heaven.

Rhodiola Rosea is another excellent complimentary supplement that pairs incredibly well with L-Theanine. While L-Theanine is an amino acid, Rhodiola Rosea is an adaptogen. That’s what makes it a great product to work alongside L-Theanine. 

Rhodiola Rosea helps the body be better able to cope with the stress that comes on a physical level. It helps support the body, while L-Theanine and GABA help to support the mind. When all three work together in tandem, it’s an amazing, holistic approach to improving mental health and promoting a feeling of calmness. 

Also, while not a supplement, combining L-Theanine with an overall healthy, balanced diet can further boost the benefits of each individual component. Focusing on getting enough of all of the essential vitamins and minerals that most diets are lacking can help improve both your physical and mental health overall. 

Many of the beneficial supplements out there, like L-Theanine, can be obtained mostly from the food products they come from. It does take a level of focus on what you’re putting into your body, but with a little dedication and planning, you can work toward changing not only your body but also your mind. 

Are There Any Drawbacks to L-Theanine?

The great news is, with L-Theanine, side effects are nearly non-existent

In healthy adults, the amino acid is incredibly well tolerated. However, everyone should contact their physician before starting any new supplement, especially those who are already being treated for any health conditions with prescription medications. L-Theanine has the potential to interact with high blood pressure medications, specifically, as well as many stimulants and supplements containing caffeine or those meant to lower blood pressure.

In addition, pregnant and breast-feeding women as well as children should take extra precautions to verify the safety of supplements before adding them to their wellness regimen. There isn’t any conclusive research to show that L-Theanine is dangerous to either of those groups, but there also isn’t enough research to show that it is safe. It’s always better to be safe than sorry in those cases.

Also, as L-Theanine may have the potential to lower blood pressure, those who already have the condition known as hypotension should make sure to ask their doctor before starting on the supplement. While the blood pressure lowering effects are temporary, having low blood pressure can cause dizziness, lightheadedness, nausea, and even passing out. 

Speaking of nausea, nausea and vomiting may also be present when first starting on L-Theanine. This can be normal, and will go away once your body adjusts. This may go hand in hand with some of the reported metabolism and weight loss side effects of the supplement.* While some wouldn’t consider that a side effect, for those who struggle with issues like eating disorders or have other body image issues, losing weight while taking a medication can actually trigger other anxiety and depression related concerns, so proceed with caution if these apply to you. 

And finally, possibly the most researched side effect, is the potential for headaches. However, this has been attributed to one of two things - high starting doses, and combining it with caffeine. To reduce the risk of headaches, start with the lowest effective dose and try to avoid drinking caffeine while taking the supplement. It may also be helpful to take an additional magnesium supplement, which has also been known to help with feelings of anxiety on its own!


L-Theanine is an incredibly safe, effective, and beneficial supplement that nearly anyone can use to help promote mental wellness. It is helpful all on its own, but especially when combined with other, complimentary products like GABA and Rhodiola Rosea. 

Check with your doctor before starting on any new supplement, but, with the lack of major side effects, you can be assured that L-Theanine is well worth the efforts. Your mental health will thank you!

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