L-Theanine is an amino acid that can be found in black and green tea and in some mushrooms. Theanine comes in two forms, D-theanine and L-Theanine. L-Theanine is the form used to improve mental function, and help with stress, mental impairment, anxiety, and other conditions.
It’s a naturally-occurring amino acid that has a chemical structure very similar to glutamate. L-Theanine helps the body transmit nerve impulses to the brain.
Some other common names for L-Theanine include theanine, teanina, suntheanine, gamma-glutamylethylamide, gamma-ethylamino-L-glutamic acid, camellia sinensis, boletus badius, and 5-N-Ethylglutamine.
In this buyer guide, we’ll provide an overview of this nootropic before we go over the top 6 L theanine powder supplements that can be found on the market!
Benefits of L-Theanine
Before you try L-Theanine yourself, it’s a good idea to learn more about the benefits it brings. L-Theanine has many potential benefits for your health that we’ll discuss below.
Improved Mental Focus
People often drink green or black tea while working in order to increase their focus, and they might be right to do so.
A study conducted in 2012 concluded that people who took 100 milligrams of L-Theanine and did an attention task had made fewer errors when compared to those who took a placebo. What also improved the focus of the people was combining L-Theanine with 50 milligrams of caffeine.
However, more research needs to be conducted in order to be able to see how L-Theanine affects the focus and attention of an individual.
A few studies have concluded that L-Theanine might help people sleep more deeply, to sleep more easily, and to relax before bedtime. A study done in 2018 had concluded that people who took 450 to 900 milligrams of L-Theanine every day for eight weeks had greater sleep satisfaction.
The people who participated in the study were taking antidepressants and had generalized anxiety disorders. The authors mentioned that there weren’t any improvements when it came to insomnia or anxiety severity.
Researchers had also concluded that doses of 250 to 400 milligrams of L-Theanine greatly improved sleep in humans and animals.
Blood Pressure Management
Those who have high blood pressure in stressful situations might benefit from L-Theanine.
One study had found that L-Theanine helped reduce high blood pressure in people who had it after specific mental tasks. That same study concluded that caffeine had a similar effect to L-Theanine, though it wasn’t as beneficial.
Maintaining a Healthy Weight
The sleep-promoting and anti-anxiety abilities that L-Theanine has might help people in their efforts to maintain a healthy weight. In order to avoid gaining weight and to be able to stick with a healthy diet, you need to make sure you limit your stress and get enough sleep.
L-Theanine also plays a big role in maintaining weight, since there’s evidence which indicates that L-Theanine might help to limit weight gain and fat accumulation.
Green tea contains L-Theanine, which creates a savory taste, also known as umami. Studies have shown that the appetite can be reduced by umami flavors, which often helps with weight loss.
The body increases the production of certain hormones like corticosterone and cortisone when it’s under stress. These changes in hormones inhibit some brain activity, including spatial learning and memory formation. The levels of the stress hormone corticosterone can be lowered with the help of L-Theanine, to counteract this interference with learning and memory.
L-Theanine might also boost some other cognitive skills. There’s research that suggests that L-Theanine can increase the reaction time and attention span in people who are prone to anxiety. Sometimes, cognitive skills are enhanced by using L-Theanine in combination with caffeine.
Studies have shown that when L-Theanine and caffeine are combined, they can increase accuracy when switching from one task to another, enhance one’s ability to process visual information, and improve attention span.
In combination with caffeine, L-Theanine can lead to improvements of alertness and number skills in people. Caffeine helps people stay focused and alert due to the fact that it’s a stimulant.
Researchers have looked at the benefits that L-Theanine provides and concluded that this compound can benefit the physical and mental health of people. A study done in 2016 has noted that L-Theanine seems to improve brain function due to its neuroprotective effects.
However, the fact that L-Theanine can improve the cognitive abilities of people hasn’t been proven by all research. Additional research is still necessary to clarify the effect that this compound has on the mental functions of people.
Precautions When Using L-Theanine
Before you use a natural product, always make sure that you check with your doctor. Some products might not combine well with other natural products or drugs. If you plan to get pregnant soon or you’re already pregnant, don’t use this product. If you’re breastfeeding, don’t use this product.
While taking this product, make sure that you avoid wine, beer, and mixed alcoholic drinks. This product might cause a feeling of sleepiness. If you’re taking this product, make sure you take extra care while doing tasks like driving or operating motorized vehicles. Check with your doctor if you’re thinking about consuming this product and you have anxiety.
You should watch out for dizziness and upset stomach.
Signs of a bad reaction to L-Theanine include:
- Swelling of throat, tongue, lips, or face
- Blue skin color
- Bad cough
- Tightness of the chest
If you experience any of these symptoms, you should visit the emergency room immediately. Look out for signs of low blood pressure, which include clammy, cool, and pale skin, thirst, fainting, and feeling tired, weak, or dizzy.
Lastly, call your doctor if you have a bad headache, loose stools, are throwing up, or see a change in your ability to think clearly.
It’s suggested that you start with a smaller dose of L-Theanine, and then increase it gradually. For stress, sleep, and similar uses, it’s recommended that you use 100 to 400 milligrams. If you’re combining it with caffeine, it’s recommended that you use 12 to 100 milligrams of L-Theanine with 30 to 100 milligrams of caffeine.
Healthy adults generally have no problem tolerating L-Theanine. However, you should consult a physician before using an L-Theanine supplement for children, if you’re an individual that has low blood pressure, or you are a pregnant or breastfeeding woman.
6 of the Best L Theanine Powder Supplements
1. L-Theanine Bulksupplements
Bulksupplements’ L-Theanine powder is clean and pure and doesn’t use any filling.
The supplement acts as a relaxing agent and helps to lower blood pressure. It can have calming effects on sleep and mood and can support focus, memory, cognition, and alertness.
You can mix this powder with a liquid such as almond milk, water, smoothies, or juice, or you can create your own capsules. The only ingredient used in this powder is L-Theanine.
The recommended dosage when you’re taking this product as a dietary supplement is about 1/5 of a teaspoon or 500 milligrams of the powder once or twice a day, or as advised by a physician.
Ingredients: L-Theanine 100 g
- Guaranteed purity
- Lab-tested for quality
- Manufactured according to cGMP standards
- Some customers complained of strong smell
2. L-Theanine Powder FitPowders
To ensure the purity of this product, it’s tested in a separate lab by a third party in the United States. The L-Theanine found in this product enhances relaxation and improves mood. The supplement contains no additives or fillers, and is 100% pure.
You should take 100 or 200 milligrams, however, make sure you’re not exceeding 400 milligrams a day. This product also includes a scoop with which you can easily measure the recommended dose of 200 milligrams. This supplement pairs great with caffeine. Take a 2:1 ratio of L-Theanine to caffeine in order to eliminate the jitters that sometimes accompany caffeine consumption.
Ingredients: L-Theanine 100 g
- Improves mood
- Promotes relaxation
- Tested by a third party
- Some users complained of a strong smell
3. Nutricost L-Theanine Powder
The L-Theanine powder by Nutricost has 500 servings, with 200 milligrams of L-Theanine per serving. The product is GMO-free and gluten-free and is manufactured in a facility that’s FDA-registered and GMP-compliant.
When using the product as a supplement to your diet, you should mix 1 scoop of the powder with 6 to 10 ounces of water, or as advised by a healthcare professional.
Nutricost is a supplement company that’s based in Utah, and as the name of the brand suggests, they aim to make supplements that are affordable for the average consumer. They offer a wide range of products, including everything from generic vitamins and minerals to more specific products such as spinach powder.
Ingredients: L-Theanine 100 g
- Manufactured in a GMP-compliant facility
- Pure form of L-Theanine
- Helps with anxiety
- Some users complained that the powder is clumpy
4. Micro Ingredients Pure L-Theanine 99% Powder
This supplement contains pure L-Theanine powder, has a natural scent, and is specially formulated for maximum benefit to the consumer.
The powder doesn’t contain any artificial flavors, colors, additives, or preservatives, and it’s vegan-friendly. The goal of the company that made this product is to guarantee the quality of the ingredients that are used in its supplements and to help people live a healthier and better lifestyle.
The product is gluten-free, and is non-GMO. It’s also been tested by a lab for heavy metals and purity. The product is packaged in a facility in California that’s FDA-registered.
The L-Theanine in this supplement supports focus and learning, and promotes relaxation without causing a feeling of drowsiness. It also balances blood pressure and supports cardiovascular functions.
You should take 100 to 200 milligrams one to three times a day with a shake, juice, or water.
Ingredients: L-Theanine 100 g
- Natural scent
- Some users have complained that the effects are slow
5. L-Theanine Powder 3.53 oz
L-Theanine promotes alpha brain waves and improves creativity, learning, cognition, and focus. It also enhances the formation of new and healthy neurons. The powder helps you to relax without feeling sedated, and it does this by encouraging healthy levels of cortisol. This reduces the perception of stress and allows you to fall asleep more easily.
It can be combined with caffeine and other stimulants. The jittery side effects that usually occur when taking stimulants can be eliminated or reduced by taking L-Theanine. This is what makes this product a great addition to your pre-workout supplements.
The daily recommended dose is 100 to 200 milligrams. To get the maximum nootropic benefits that this product has to offer it’s usually combined with caffeine or other stimulants.
The company offers a full refund if you decide you aren’t satisfied with the product.
Ingredients: L-Theanine 100 g
- Promotes healthy blood flow
- Synergistic with caffeine
- Improves focus
- Doesn’t include a measuring scoop
6. L-Theanine Powder by Pure
This product improves mood fluctuations, concentration and focus, and heart function, and offers natural relaxation, and relief from stress and anxiety. The L-Theanine powder by Pure has non-protein amino acids, high purity and quality, is found naturally in black and green tea, is a rich source of antioxidants and polyphenols, and has eco-friendly packaging.
The product is suggested to be used as a supplement to your diet. You should consume 1/8 of a teaspoon one to three times per day with a smoothie, juice, water, or a liquid of your choice.
The company that manufactures this product offers a 100% money back guarantee. You can return the product and get a full refund in case you’re not satisfied with your purchase.
Ingredients: L-Theanine 113.4 g
- Good for stress relief
- Improves fluctuations in mood
- It has eco-friendly packaging
- Some users complained of a racing heart as a side effect
L-Theanine affects the level of chemicals in the brain, including dopamine and serotonin, which influence emotion, sleep, and mood. L-Theanine supplements can help improve the way that your body deals with stress, alongside many other benefits they provide.
We hope that this buyer’s guide provided a thorough overview of L theanine powder, including its benefits and risk factors.
 John J Foxe, Kristen P Morie, Peter J Laud, Matthew J Rowson, Eveline A de Bruin, Simon P Kelly, Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task, 2016
 Jerome Sarris, Gerard J Byrne, Lachlan Cribb, Georgina Oliver, Jenifer Murphy, Patricia Macdonald, Sonia Nazareth, Diana Karamacoska, Samantha Galea, Anika Short, Carolyn Ee, Yoann Birling, Ranjit Menon, Chee H Ng 3, L-Theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial, 2018
 Jackson Williams, Jane Kellett, Paul Daniel Roach, Andrew McKune, Duane Mellor, Jackson Thomas, Nenad Naumovski, l-Theanine as a Functional Food Additive: Its Role in Disease Prevention and Health Promotion, 2016
 Ai Yoto, Mao Motoki, Sato Murao, Hidehiko Yokogoshi, Effects of L-Theanine or caffeine intake on changes in blood pressure under physical and psychological stresses, 2012