James Davis

L-Theanine Reviews - What Is It?

WARNING: DO NOT BUY L-Theanine Until You Read This Review!
Is it a Scam? Does It Really Work? Check Ingredients, Side Effects and More!

L-Theanine is an amino acid that is usually not found in the common diet and is deemed a nondietary amino acid similar to L-Citrulline or L-Ornithine. It is structurally similar to glutamine and neurotransmitters that are produced from it (glutamate and GABA). It can reach the brain and start working almost immediately after ingestion. Its properties make it a relaxing agent without sedation, as well as stress reliever and booster of focus and attention. L-theanine is not claimed to induce sleep, but it can help to improve sleep but it is certainly not the best treatment for this purpose. The attention promoting and relaxing properties of the product are coupled with low sedation. L-Theanine combined with caffeine (200mg) is said to be beneficial for better cognition and attention.

In this way, L-Theanine is rather a relaxing not sedating amino acid that can be used in combination with stimulants such as caffeine. It shows effectiveness by itself in the dosages that can be found in most supplements but it can also be received via a diet. It can be found in green tea and black tea. There are some health benefits linked with the ingestion of tea but L-Theanine is usually contained in very low doses in tea. The benefits of green tea are more related to the catechins and theaflavins contained in it. It is thought to be associated with better cardiovascular health and some cognitive benefits. Is L-Theanine really beneficial for your health? Let's find out by discussing it more deeply.

Ingredients of L-Theanine - Does It Really Work? Is It a Scam?

L-Theanine is an active ingredient in the product. This is a non-dietary amino acid, which means that it is not required in the diet to maintain life. This is a non-protein amino acid; it is not used to make enzymes. Its technical name is r-glutamylethylamide, which is known as a sedative amino acid. In general, L-Theanine can be found in the leaves of camellia sinensis (the plant used to produce green, black, and white teas; source of green tea catechins). It ranges from 25mg to 60mg per 200mL serving of tea. This is the reason why Theanine is always associated with green tea. Actually, it comprises up to 50% of total amino acids contained in tea. L-theanine is similar to the neurotransmitters GABA and glutamate in its structure.


It is interesting to mention that L-theanine may alter the taste perception by reducing the bitterness of products such as chocolate, caffeine, zinc, and grapefruit, since it is a substrate of the umami perception on the tongue. L-theanine is synergistic with the umami research drug inosine 5-monophosphate. It is the only agent in green tea that creates the sensation of umami. It can negate the taste of bitter stimuli a little, and seems to be the molecules that form the umami taste of green tea. It should be noted that the fermentation process of tea leaves reduces the content of L-theanine, while the drying process increases the content of theanine in tea, better to say, increases the percentage of this substance in tea by weight. It should be mentioned that younger plants have a higher concentration of theanine than older plants. Let us take a look at possible side effects associated with the intake of this substance, as well as at the real users' reviews available online.

Customer Reviews - Does It Have Any Side Effects?

The most commonly reported side effect of L-Theanine is stomach upset and related discomforts linked to gastroenterological tract. The delivery method of the product is drinking the supplement with a caffeinated beverage such as green tea or coffee. The acidity of the drink can irritate the bowels and stomach of some people. As a result, they may experience diarrhea. This side effects is caused not by the L-Theanine itself. Some secondary side effects are also possible. Thus, the production of GABA, could lead to headaches. This side effect can be reduced with simple moderation. This happens because some people's bodies perceive L-Theanine as a nootropic supplement. Many readers are interested whether L-Theanine can be safely combined with alcohol. Well, there is no recorded negative interaction and it is unlikely that you will experience side effects from using these two items in combination. It is not excepted, though, that an individual may experience an unusual reaction due to personal sensitivity. One limited research in mice has demonstrated that L-Theanine can prevent some forms of liver damage due to the alcohol consumption. It is said to prevent alcoholic liver injury through providing antioxidants to the body. This supplement can also prevent hepatoxicity by decreasing the amount of alcohol in the blood flow. This is not applicable to humans, so taking L-Theanine with alcohol is at your own risk. What is known for sure is that this supplement can significantly decrease blood pressure, which can be risky for people who already have hypotension or who are taking blood pressure lowering drugs.

There is a great number of customer reviews about the product online. There are both positive and negative testimonials. Some users are pleased with the action of L-Theanine in their bodies, but many customers have a number of complaints. Thus, one reviewer reports that after one dose (100mg) he experienced severe abdominal cramping and chest pain. He didn't take the product for two days and then he took a dose again. As a result, he experienced even more severe surges of pain. The man was horrified with side effects and stopped using the product. Another female customer wrote in her review that L-theanine made her a little relaxed mentally but it gave her unpleasant heart palpitations. She stopped it too. One customer described in his testimonial that he took one 200 mg pill with dinner. After about an hour the man felt relaxed, and tightness had gone. But he suffered from insomnia all night. The man woke up several times and was not able to work the next day. He definitely had a strange reaction to the product. Let's take a look at some actual customers' reviews available online.

"After four days of taking L Theanine I noticed unusual symptoms after drinking the Matcha tea. I felt calm but also amped up. I didn't sleep well. One night I could hardly sleep and the next morning I had a series of absence seizures. I am sure it was because of L-theanine because I know that it increases the threshold for some seizures and decreases the threshold for some other types. I certainly discontinued taking it"

"I already drank green tea, and did not know that L-theanine was in my other multivitamin supplement. Its content was probably too high, so that I felt very dizzy after a few days of taking the supplement. I could not drive or think well. It also caused fatigue for me, although I am a 46-year old man in good health. I could have crashed my car if I had driven yesterday. Please do not drive when using this product"

"I started taking L-Theanine two weeks ago for my insomnia. I combined it with lavender oil to improve my sleep. It really helped me to shut my brain off at night, but it made me feel extremely dizzy. I also suffered from severe headaches and stomach upset. Today I had such a bad dizzy spell that I fell and hurt my hip. I am a woman of 37 years of age"

Where To Buy L-Theanine?

The supplement can be bought anywhere including from such retail stores as Amazon, GNC, Walmart, and others. The cost may depend on the brand, concentration and number of pills. For example, L-Theanine 200 mg (60 Veg Capsules) from NOW Foods costs $12.99 plus free shipping on Amazon.

My Final Summary

L-Theanine is a unique supplement used for many purposes. It is available in different forms and concentrations but before taking this substance, it is better to consult your doctor. This product can be associated with certain side effects including stomach-related discomforts, headaches, a reaction of a personal sensitivity, low blood pressure and some others. It does not provide equal effects for all users, which is why you should be careful with this product. It can negatively affect your sleep. Taking into account everything we have learnt about L-Theanine, I cannot recommend it to usage.