L-Theanine Review – Its Effects, Dosage, Benefits, Risks & More

According to Psychology Today, L-Theanine was discovered by Japanese scientists in 1949 and is thought to be a source of umami in some foods – it gives them an excellent earthy kind of taste.  

L-theanine is an amino acid, which is an organic compound that plays a vital role in building proteins in the body. Amino acids assist your metabolism. We create our own amino acids, and there are plenty of different kinds of them.

Human's don't need L-theanine like they need Vitamin C or Calcium, and we don't create this one ourselves, but that doesn't mean it can't be beneficial to us.

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How Does L-Theanine Work?

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L-theanine works by doing three different things: boosting levels of calming brain chemicals, lowering the levels of brain chemicals which cause excitement, and triggering the release of alpha brain waves. 

All of these combined let L-theanine allow us to be in a state of wakeful relaxation and operate with less anxiety throughout the day, while also staying more alert.

In addition to being more alert and relaxed, L-theanine is also known to make changes in appetite, how energetic we feel, and other cognitive skills. 

Gamma-Aminobutyric Acid

One of the amino acids that the human body creates is gamma-aminobutyric acid or GABA. GABA is a brain chemical that promotes relaxation by blocking particular activity in your nervous system. 

L-theanine boosts your levels of GABA, which in turn lowers chemicals in the brain, which are responsible for anxiety and stress.

It is how L-theanine allows us to feel more relaxed. At the same time, it doesn't lower stimulating brain chemicals to the point that we begin to feel drowsy. One of the best things about L-theanine is how it manages to balance its own effects on you.

Alpha Brain Waves

Alpha brain waves are responsible for how you feel when you’re daydreaming or meditating – they promote relaxation. 

These brain waves also occur during REM sleep, while you’re dreaming. L-theanine is known to trigger a release of alpha brain waves, which allow you to better relax and focus. 

L-theanine is also known to help elevate levels of serotonin and dopamine, so if you’re ever feeling a little down, a quick dose may do the trick. 

What Are The Benefits Of L-Theanine?

We’ve discussed the primary benefits of L-theanine, which involve feeling more relaxed and less anxious. But these are just primary benefits. In truth, there are a host of secondary benefits – being more relaxed and less anxious simply makes your life easier. 

1. Better Focus

According to Medical News Today, people who took 100 milligrams (mg) of L-theanine made less mistakes at work than a placebo group. 

2. Improved Sleep

What does being relaxed and not stressed out help us do? It helps us sleep. A 2018 study discovered that individuals with Generalized Anxiety Disorder who took 450mg to 900mg of L-theanine daily for 8 weeks began to sleep better. These people with GED were also taking anti-depressants.

3. Relaxation

While L-theanine may help you feel mentally relaxed, it also physically reduces an individual's resting heart rate. It means it's not all in your head – you really are loosening up.

4. Increased Cognition

L-theanine helps your brain work better. It not only enables you to focus on important tasks, but it, in general, allows your overwhelmed thoughts to slow down.

In addition to all of these, L-theanine has also shown to help with weight loss, boost your immune system, reduce blood pressure. A study has also shown that it may help the chemotherapy drug doxorubicin be more effective against cancer.

Downsides Of L-Theanine

Just as with anything that may be good for you, there are always situations which may render such things more harmful than helpful. 

L-theanine has some great benefits, but it still a foreign amino acid which human beings do not create on their own. Everything in moderation.

  • L-theanine is not a medication, and many studies still needs to be done on how it affects us, so there aren't a whole lot of guidelines on how to take it.
  • It may interact with medication and supplements for blood pressure, whether they be for hypertension or hypotension.
  • It may interact with medication used for attention deficit hyperactivity disorder or ADHD
  • It may also interact with caffeine
  • WebMD specifically highlights that L-theanine is “POSSIBLY SAFE when taken by mouth, short term. That means there are definitely risks.
  • L-theanine might have side effects like headaches or sleepiness.
  • We aren't sure how it affects child or women who are pregnant or breast-feeding.

This list of cons is basically yelling at you to talk to your doctor first.

Where Does L-Theanine Come From?

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Now that you've gotten past the part that reads like a prescription drug commercial. Let's get to the exciting stuff.

L-theanine is found in tea leaves! It can also be found in Bay Bolete mushrooms, but we don’t care about those right now, because now we know why drinking tea is so relaxing. 

L-theanine is specifically found in black and green teas, not herbal teas or tisanes, which don’t actually have tea leaves in them. 

L-theanine is also available in supplement form at many drugstores, but if you have tea at home, why not brew yourself a cup instead?

L-Theanine And Umami

If you don’t know what umami is, it’s often easy to understand it by placing it in a category. Some foods are salty, some foods are bitter, some are sweet, and then some have umami – a kind of flavor often described as savory or brothy. Mushrooms and aged foods have umami flavors to them. 

L-theanine was discovered in green tea leaves. Unsweetened, green tea has an umami flavor, and L-theanine is thought to be the source of that umami. Umami is common in foods that have high levels of L-theanine and other glutamates.

How L-Theanine’s Umami May Have Additional Health Benefits

Mono-sodium glutamate, or MSG, is a naturally occurring salt in tomatoes, Parmesan cheese, and seaweed, among other things. MSG additives for cooking come from seaweeds like kombu. It is another source of umami, like that in your Chinese take-out or miso soup.

L-theanine has a unique relationship with umami because umami also links it to other health benefits. 

Scientists studying umami as a flavor have discovered that umami may be linked to a decreased risk of obesity. It may also help boost metabolism and help you feel full for longer. 

What Studies Have Been Done On L-Theanine?

There is always buzz online about what new diet supplements are on the trend to help you lose weight and boost your metabolism, but it’s hard to know what’s real and what’s not. Luckily, there has been plenty of study on L-theanine and its effect on our mental state. 

One such research paper was written by Anna C Nobre, PhD, Anling Rao, PhD, and Gail N Owen, PhD. Together they wrote “L-Theanine, a natural constituent in tea and its effect on mental state,” which was published in the Asia Pacific Journal of Nutrition. 

Their abstract directly outlines the many benefits of L-Theanine that we have already talked about. 

Real Scientific Studies and Results

The research that they conducted involved measuring alpha brain waves on “healthy, young participants” using EEG’s. One group of participants had ingested L-theanine some time before and had a noticeable increase in alpha brain waves, while the placebo group did not. 

Doctors Nobre, Rao, and Owen concluded that “L-theanine, at realistic diet levels, has a significant effect on the general state of mental alertness or arousal.”

So, in case your skeptical on how L-theanine affects us, you can be assured that there is conclusive scientific evidence.

The Ironic Partnership Of L-Theanine And Caffeine

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An overview of multiple studies on L-theanine on Examine.com concludes that L-theanine has a synergistic relationship with caffeine. While caffeine may help you stay alert and keep focus, it can also make you anxious and jumpy. 

Even though L-theanine promotes alertness just like caffeine does, it does so by creating a specific balance between the brain chemicals which relax over the brain chemicals which excite. 

Tea Vs. Coffee

Have you ever gotten the shakes after a few too many cups of coffee? L-theanine doesn't do that. It helps promote relaxation without drowsiness. Combined with caffeine, L-theanine helps to improve focus and cognition.

Tea has caffeine in it, but not as much as coffee. Black tea has more caffeine than green tea. So, if you’re reaching for a hot drink in the morning but don’t want to end up with hand tremors by lunch, reaching for a cup of tea may be exactly what you need. 

L-Theanine For Your Pets!

So many dogs or cats have anxiety. They tear up the house because they're stressed. They get separation anxiety when you're not home, and you may come back to a massacre of couch cushion strewn about your living room regularly.

According to the Doctor of Veterinary Medicine Elizabeth DeLomba, L-theanine can be used as a non-prescription method to help reduce anxiety in pets. 

She writes that it can be administered to both dogs and cats and remains in their system for about 24 hours after oral ingestion, so it’s a once a day kind of supplement. 

L-Theanine's Effects in Dogs and Cats

Dr. DeLomba also says that L-theanine promotes reduced blood pressure and heart rate, helps with muscle relaxation, helping your pet sleep better, and helps senior pets with cognitive issues.

She writes that L-theanine can help your pet feel less irritable and anxious. So, if you're having some problems with pet anxiety, it might be something to ask your vet about.

How Do You Use and Dose L-Theanine Correctly?

l theanine soage

Dr. Michael Breus keeps a blog titled “The Sleep Doctor.” Breus is a Clinical Psychologist who is involved with the American Board of Sleep Medicine as well as the American Academy of Sleep Medicine. He specializes in sleep disorders and often tells his patients to drink tea.

Dr. Breus wrote a post entitled, “Understanding L-theanine: Sleep better at night, feel relaxed and alert during the day” in which he discusses the benefits of L-theanine and drinking tea in regards to improved sleep. He also discusses what to know about taking it and what doses to use. 

Staying Safe With L-Theanine

Just like any dietary supplement or medication, always consult your doctor. There's a difference between drinking tea to your heart's content and taking over the counter pills or tablets. 

Don't just dive in headfirst if you want to start taking L-theanine in supplement form, especially if you're on other medications or supplements.

Dr. Breus provides dosage suggestions based on doses that have been investigated in scientific research. He writes that 100mg to 400mg should help with sleep, stress, and other issues. 

In combination with caffeine, one should take between 12mg and 100mg of L-theanine with 30mg to 100mg of caffeine.

Some people, a lot like me, find it easier to hear and watch information rather than read about it. Here is an educational video about L-theanine, complete with citations from actual scientific studies. 

Wrapping It Up

You’ve made it to the bottom of this long list of paragraphs. What have we learned from them?

L-theanine has a lot of benefits regarding wakeful relaxation, better focus, and improved cognitive performance. 

You might find that drinking tea help you do all of these things, but if you need a little extra help and are interested in L-theanine as a supplement, consult your doctor to see if it’s right for you. 

L-theanine and caffeine work together to provide synergistic results. If you need a little pep in your step, combine the two for improved alertness through the day without increasing your anxiety or getting jumpy. 

Multiple studies have been done on L-theanine and how it affects us, but there is still plenty of research to be done, as we don’t yet have any official guidelines on dosage and risks. 

Last but not least, go have a cup of tea!

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