L-theanine: Benefits, Uses, Side Effects and Dosages

l theanine benefits uses dosages

According to various studies, natural foods contain different types of compounds with numerous health benefits. One of these compounds is L-theanine. This compound can be found in black tea, green tea, and even in some types of mushrooms. However, some of the pharmaceutical companies have been able to synthesize it to develop supplements that can be taken alongside meals and medication.

Researchers have been working on determining the benefits of L-theanine to your body. Recent studies indicate an improved mental focus and better sleep.

This article seeks to understand L-theanine, its benefits, uses, side-effects, and dosages.

What is L-theanine?

l theanine for anxietyThis compound is also known as Gamma-glutamyl-ethyl amide or N-ethyl glutamic acid.

The compound occurs naturally in green tea, black tea, and specific types of mushrooms. Aside from improving mental focus, this compound also reduces anxiety, stress, and other mental impairment conditions. The compound works by affecting the levels of certain brain chemicals. Some of which include dopamine, cortisol, and serotonin. These chemical are known to influence your sleep patterns, moods, and overall emotions.

By changing the balance of these chemicals, this compound significantly influences the person’s emotional state.

Uses of L-theanine

There are several research programs dedicated to understanding how this compound affects your body and how it can be used to manage different conditions. Some of the studies are inconclusive, while others have a proven record of working efficiently. Here are a few uses of L-theanine.

Boost cognitive function

Taking L-theanine can help you increase your concentration span, allowing you to stay focused on the task at hand for a long period of time. People with low cognitive skills can use it to perform tasks that require elevated mental capacity. However, research is still working on proving if combining L-theanine with caffeine is effective or if each compound is effective on its own.

Anxiety Relief

Studies show that taking L-theanine daily for a period of time can help reduce stress-related anxiety. However, more research needs to be conducted to ascertain if it can be used to manage other types of anxiety.

Boost concentration span

When looking to improve your ability to pay attention, you need to follow specific guidelines. Research indicated that taking 200mg of L-theanine helped boost the subject’s concentration span. However, lower doses proved ineffective.

Managing ADHD

Studies show that the use of L-theanine can be used to improve cognitive skills in children with ADHD. However, this compound does not do much in terms of impulse and attention control. Another research also showed that the use of L-theanine could help improve sleep quality and reduce night activity in male children with ADHD aged 8-12 years.

Control diarrhea caused by cancer treatment

Consuming supplements and foods with L-theanine and L-cysteine can help reduce diarrhea and boost appetite in cancer patients undergoing treatment.


Previous studies suggest that oral ingestion of L-theanine, especially when going to bed, for two months helps decrease symptoms of depression and even improve their sleep quality.


a combination of L-theanine and other prescription medications can help manage the symptoms of schizophrenia. However, researchers are still working on ascertaining the effectiveness of this use.

Other uses of this compound include managing Alzheimer’s diseases, flu, high blood pressure, and insomnia. As of now, more studies are still underway to ascertain the effectiveness of the use of L-theanine to manage, treat and control certain conditions. Even with research still underway, here are a few benefits of using L-theanine.

Benefits of L-theanine

L-theanine has in the past been known for helping people stay calm. However, o9t also has other health benefits such as:

Anxiety and stress relief

L-theanine is found in black tea and green tea. This means a sip from your favorite mug can help you ease up, with more studies showing that this compound not only helps you relax, but it works without causing drowsiness. Various studies have since shown that taking L-theanine can help reduce stress levels and even manage anxiety in people who find themselves in stressful situations. Aside from helping normal people deal with their anxiety, pairing this compound with other prescriptions can help patients with schizoaffective disorder and schizophrenia deal with their anxiety levels, in turn improving their symptoms.

Increased focus

L-theanine can be used alongside caffeine to help you pay more attention and boost focus. A study showed that a combination of 97mg of L-theanine and 40mg of caffeine helped boost the concentration span in adults, especially those performing demanding tasks. Further results showed that the participants were more alert and were less tired compared to the control group.

Immune boost

Several studies show that L-theanine can be used to boost one’s immune system. One of these studies, recently published on the Beverage, showed that the compound could be used to deal with upper respiratory tract infections. More and more studies have come up to support this claim, with one suggesting that a mixture of theanine and the antioxidants in green tea can help keep flu at bay.

With more research into the validity of some of these benefits, a researcher indicated that theanine could also be used to improve inflammations in the intestinal tract.

Tumor and cancer treatment

L-theanine has for some time been associated with some cancer treatments. Some research indicates that this amino acid could be useful in amplifying the anti-tumor effects of specific cancer treatment drugs. The data to support some of these claims are limited. However, studies are indicating lower cancer risks in people who regularly drink tea. With adequate research, scientists are exploring new ways to combine L-theanine and chemotherapy to fight cancer effectively.

To support this claim, a researcher in China conducted a study that found that women who have ovarian cancer who took a cup of green tea daily lived longer than those who didn’t. This study was mirrored by another study that showed that women who drank green tea were less likely to get diagnosed with pancreatic cancer, unlike non-drinkers.

Blood pressure management

According to various research studies, L-theanine can prove invaluable to people with increased blood pressure, especially when dealing with stressful situations. Taking L–theanine when experiencing elevated pressure levels or after performing certain mental tasks can help reduce your blood pressure. The effects of theanine can be compared to caffeine. However, caffeine is considered to have fewer benefits. One of the best ways to reduce pressure levels is by having a quality sleep. With theanine, you can have a good night’s sleep and wake up refreshed and more relaxed to tackle the day’s events.

To get the best out of theanine, you need to take the right doses. One study showed that taking 250-400mg of theanine before going to bed can help improve your sleep. To reduce your resting heart rate and promote relaxation, you can take about 200mg of L-theanine.

Help with weight loss

Most people today are struggling with weight loss. However, to get you on the right track, you can start by replacing some of the junk foods with green tea to help with your weight loss plan. L-theanine is known for creating a savory taste that lowers your appetite—being in control of how and what you eat can be a plus for weight loss.

Scientific Opinion

L-theanine is not produced in the body. This means you have to ingest it from different sources. Numerous studies have been conducted to ascertain the effects of using L-theanine. As of now, the compound has been proven to be beneficial to your mental and physical health. Some of the studies are inconclusive since scientists are yet to conduct extensive research in humans. Most of the previous studies were conducted on small sample size. Data from these sample sizes may not be considered conclusive compared to those from larger sample sizes. In some cases, scientists used animals such as mice and rats. If the same study was conducted on humans, they are likely to act differently, making some of the results inapplicable.

This brings us to the question, is L-theanine safe. A general consensus from various experts and government agencies categorizes the compound as ‘generally safe.’ This means, when used appropriately or as indicated, then the additive cannot cause any harm. On the other hand, pregnant women and lactating mothers are discouraged from using products containing L-theanine.

Side effects and interactions of L-theanine

Aside from the numerous benefits that come with using L-theanine, it also has some side effects. These side effects present themselves differently in people. However, those who take the supplement version can interact with some medications. Before taking this compound, it’s advisable to consult with your doctor, especially when under different medications.

Research shows that L-theanine interacts with certain drugs and supplements, including:

  • Those used for treating high blood pressure include hydrochlorothiazide, furosemide, valsartan, losartan, and enalapril, among many others.
  • Supplements are used to lower blood pressure.
  • Stimulants used in treatment programs such as ADHD include epinephrine, diethylpropion, and pseudoephedrine, among others.
  • Supplements containing caffeine.

When it comes to pinpointing the exact side-effects of taking L-theanine, there are no documented direct side effects. This means it’s safe to drink tea or take supplements with L-theanine. However, it’s worth noting that most drug law enforcers don’t regulate supplement manufacturers. Manufacturers are tasked with the responsibility of ensuring their products are safe.

Besides L-theanine showing anti-tumor properties, tea with amino acids may contain other ingredients that may prove harmful to cancer patients. This claim is supported by research that showed that the polyphenol EGCG in green tea has a negative impact on the efficiency of certain chemotherapy drugs, bortezomib. It’s because of these scenarios that it is advisable to consult with your health care provider on whether to incorporate green tea into your treatment plan or shelf the idea.

l theanine green tea

Consuming large amounts of green tea has been known to cause nausea, irritability, and stomach upset. As stated before, pregnant and lactating mothers need to limit their intake to reduce the chance of over-caffeinating. The safe use of L-theanine, even for children, can only be determined by a qualified healthcare provider.

Precautions and warnings

Pregnancy and breastfeeding

there is limited data on the effects of L-theanine on pregnant and lactating mothers. However, it’s best to exercise caution when using it. In some cases, it is best to avoid it completely.


this compound is relatively safe for children. However, it’s best to consult on the appropriate dosage. Some experts suggest 200mg twice a day for up to 6 weeks.

Low blood pressure

L-theanine can be used to lower blood pressure. However, some scientists suggest that continued use of the compound could cause the blood pressure to drop below the safe mark, making you susceptible to low blood pressure. People suffering from low blood pressure are encouraged to discuss their options when it comes to using L-theanine.


L-theanine is not considered a form of medication. Hence, there are no specific guidelines on what amount is safe to consume. However, ingesting the supplements is likely to cause an overdose. Most supplements come in 200mg tablets. All you need to do is consult with your physician on the correct amount to take.

In the case of those drinking tea, it is advisable to follow the general consumption guidelines used for caffeine. This way, you can consume the right amount of tea.

For those looking to use L-theanine to boost their cognitive function, a single dose of 100mg can be effective just before a test or activity. In some cases, experts suggest a dose of 200mg daily for a month.

When combined with caffeine, it’s best to balance your intake. You may have to range your doses between 30 to 100mg of caffeine and 12 to 100mg of L-theanine.

Bottom Line

There are numerous studies currently being conducted on the use of L-theanine. Some of these studies have yielded conclusive results, while others are still at the development stages. Regardless, there are several advantages of using L-theanine, especially when used correctly. Just like any other additive, you need to exercise caution when using L-theanine. It’s best to research extensively and even consult your doctor on the safe use of the amino acid.