Perhaps you wish you had your youthful mind and figure back, or you want to boost your grades while losing the pounds you’ve gained from using junk food to get through study. 

L-theanine has gained attention for its potential to assist in both these areas: improved cognition and weight loss. But what does the research say? Let’s dig deeper to find out whether L-theanine shapes up to its reputation. 

Key Takeaways: L-Theanine for Weight Loss and Memory Boosting

• Taking L-theanine can enhance your levels of GABA, dopamine, and serotonin, improving sleep, motivation, and mood. 
• It may therefore be helpful in indications such as attention-deficit hyperactivity disorder (ADHD), insomnia, and anxiety.
• Through increasing alpha waves, an L-theanine supplement may boost subjective alertness.
• Its effect on the autonomic nervous system, including heart rate, could make L-theanine a helpful tool in protecting against physical and psychological stresses. 
• There is little evidence that L-theanine has anti-obesity effects, including the prevention of body weight increase. 
• There are many nootropic supplements including L-theanine with benefits that go beyond that of green tea extract alone. 

What Is L-Theanine?

L-theanine is a natural constituent of green tea, made from the amino acid glutamate. It is a non-protein amino acid, meaning it features the nitrogen-containing amino acid backbone. However, it is not used to make proteins in the way that proline, glycine, and other more familiar amino acids are. It is a free-standing molecule instead [1]. 

What Is the Structure of L-Theanine? 

L-theanine is similar in structure to glutamic acid, or glutamate. This is how it can interact with glutamate receptors and inhibit its activity. L-theanine is a molecule with a linear chain, and a similar configuration of side-groups, including a ketone group (a double-bonded oxygen atom) [1]. 

How Is L-Theanine Extracted and Isolated? 

L-theanine can be extracted from green tea using hot water, so even just drinking green tea gives you a low dose of the amino acid. Water is the safest and cheapest solvent, with no toxicities as seen with chemical solvents. 

To be exact, the best conditions for extracting green tea involve a temperature of 80 degrees Celsius (176 degrees Fahrenheit) and 30 minutes of steeping time. They also require a tea leaf particle size of 0.5–1mm, and a water-to-tea ratio of 20mL:1 gram [1]. 

However, many commercial supplements use L-theanine extracts from tea waste, left over from polyphenol extraction. Methods such as copper salts or surfactants can bind to L-theanine and separate it, then these are broken off to leave purified L-theanine [2]. 

How Does L-Theanine Work? 

L-theanine is a glutamate receptor antagonist, meaning that it blocks activity of the stimulating neurotransmitter. Through binding to the NMDA receptors, L-theanine protects neurons (brain cells) against being fatally overstimulated. It also increases levels of GABA in the brain, which in turn raises dopamine and serotonin [3]. 

Dopamine plays key roles in motivation, focus, and memory. It helps you perceive making an effort to achieve something as worthwhile, banishing that “can’t be bothered” feeling. The effects of dopamine on memory center around reinforcing new information you have learned when you revise it, or when you learn related information and need to make connections [4]. 

Uses of L-Theanine in the Body

The effects of L-theanine mainly involve the central nervous system and metabolic functions:

1. Boosting in alpha brain waves, which increases subjective alertness.
2. Improving motivation through an increase in dopamine.
3. Increasing the sedative neurotransmitter, GABA.
4. Relaxing the autonomic nervous system.
5. Priming innate immunity to pathogenic bacteria.
6. Potential anti-obesity effects by reducing body fat accumulation.
7. Possible ability to reduce blood levels of triglycerides.

Sources of L-Theanine

L-theanine is found in green tea and certain edible mushroom species. Matcha and gyokuro green tea are the richest sources of L-theanine, containing more than sencha varieties. All of these come from the Camellia sinensis plant, the same species that black tea comes from. 

An average cup of green tea contains 25 mg of L-theanine. On the other hand, clinical studies show that you need a dose of 50–100 mg of L-theanine to improve your attention, which is two to four cups. Drinking tea may therefore give you some benefit, but you may need an L-theanine supplement for best results [5]. 

L-Theanine Benefits

Clinical and laboratory studies show that the potential benefits of L-theanine include:

1. Weight loss.
2. Improved focus.
3. Better cognitive performance.
4. The ability to decrease blood pressure.
5. Immune system support.
6. Relief of stress and anxiety.
7. Improved sleep quality.

1. Weight Loss

L-theanine alone does not promote weight loss, but it may have an effect alongside the caffeine and catechins found in green tea—making them common ingredients in weight loss supplements. 

A lab study on mice found that different combinations of L-theanine, caffeine, and green tea catechins could both reduce weight gain and blood levels of triglycerides. However, the best combination was caffeine and green tea catechins together. 

When the constituents were tested individually, L-theanine was the most effective, equal to whole green tea powder. All of them reduced the gain of visceral fat. This type of fat sits in and around the organs and can have negative effects on metabolic health [6]. 

2. Improved Focus

Whether we have everyday fatigue or a condition such as attention-deficit hyperactivity disorder (ADHD), many of us could benefit from improved focus. A trial testing three doses of L-theanine in healthy volunteers found that the highest dose, 400 mg, significantly improved brainwave patterns related to attention span [7].  

3. Better Cognitive Performance

We all want to protect and restore our cognitive performance as we age. A study of Japanese volunteers in their 50s and 60s found that 100 mg of L-theanine significantly improved working memory and reaction times after just one dose.

The participants all had subjective cognitive impairment, meaning they noticed a decline but it wasn’t severe enough to be categorized as mild cognitive impairment or dementia.

Long-term benefits of L-theanine involve improved brain cell regeneration and protection of the neurons you already have through reducing glutamate. Glutamate is a stimulating neurotransmitter, and in excessive levels, it can kill off neurons [5]. 

L-theanine also showed to have slight improvements for working memory, motor speed, and verbal fluency

4. Lowering Blood Pressure

During stressful situations, L-theanine may prevent the increase in blood pressure triggered by the fight-or-flight response. A study on people taking cognitive and cold pressor tests found that L-theanine significantly reduced the blood pressure spike during mental tasks. As this was related to a reduction in psychological stresses, it was likely caused by stress reduction [8]. 

5. Supporting the Immune System

L-theanine may support innate immunity, your rapid yet non-specific first response to infection. It can convert to ethylamine, which mimics a type of molecule found on the cell walls of bacteria. This means that L-theanine can prime immune cells to react in a faster, stronger manner to bacterial infections, sometimes before they can cause a clinical disease state [9]. 

6. Relieving Stress and Anxiety

If you’re about to take on a stressful task, such as an exam or public speaking, L-theanine could give you a helping hand. A trial where volunteers performed a math test found that the amino acid reduced physiological anxiety symptoms by acting on the autonomic nervous system. Heart rate, heart rate variability, and levels of protective antibodies in the mouth all improved [10]. 

Additionally, L-theanine relieves positive symptoms in schizophrenia and schizoaffective disorder patients. These include mood dysphoria, which can involve stress and anxiety, and autistic preoccupation. Taking L-theanine alongside medication appeared to be safe [3]. 

L-theanine decreased the self-rating depression score compared to the placebo, which remained the same

7. Improving Sleep Quality

L-theanine may improve sleep quality, meaning you enjoy greater benefits from the same time spent asleep. A double-blind, placebo-controlled trial involving boys with ADHD found that L-theanine increased sleep efficiency by triggering a deeper sleep. It didn’t improve sleep duration, however. 

These results included both subjective and objective sleep quality, meaning it was not merely a case of the boys feeling better. The researchers used both a parents’ survey and an Actigraph watch to record data. The neurotransmitter GABA is likely behind L-theanine’s ability to enhance sleep quality [11]. 

L-Theanine for Weight Loss

Currently, there is no placebo-controlled clinical trial showing that L-theanine is effective for weight loss. As described above, L-theanine may inhibit fat accumulation, but it did not cause weight loss and the study was performed on mice. 

L-theanine may have indirect effects on body weight through reduced stress. Stress often leads to overeating, so its relaxing properties could prevent the temptation to binge on comfort food. Increasing dopamine is also known to reduce appetite and lead to weight loss, as seen with Adderall use [6].

No supplement is a substitute for a healthy diet, however, but reducing junk food cravings may help you go a long way in achieving your goals. 

L-Theanine Side Effects

Generally, research demonstrates that L-theanine is safe, with no significant side effects. One trial involving boys with ADHD did have one participant drop out after he developed tics. However, he had a previous history of tics so it may not have entirely been the result of L-theanine supplementation [11]. 

L-Theanine Interactions

There is a theoretical chance that L-theanine may increase the potency of certain chemotherapy drugs used to treat cancer. Whether this is a positive effect, through enhanced anticancer actions, or a negative one through worsened side effects, is unclear [12]. 

L-Theanine Contraindications

As L-theanine boosts levels of dopamine and certain other neurotransmitters, it may be best to avoid it if you need to take other medications that work on the same pathways. For example, Adderall is a powerful dopamine-enhancer. You may feel too manic and irritable if your dopamine levels are already high from other drugs. 

On the other hand, L-theanine appears to be safe in cases of schizophrenia and schizoaffective disorder. These conditions are viewed as contraindications for substances that boost dopamine, but the calming properties of L-theanine may cancel out any overstimulating properties [3]. 

Best L-Theanine Supplements

L-theanine is a popular ingredient in nootropics and natural alternatives to Adderall. These are a category of supplements aimed at improving and protecting cognitive function, including nootropics for motivation, energy, and neuron regeneration. 

When choosing a dietary supplement with L-theanine, it’s important to look at two factors. How much L-theanine will you get per dose, and are the other ingredients’ effects in line with what you need? 

Mind Lab Pro

Mind Lab Pro is an 11-ingredient nootropic “stack” that aims to enhance neurotransmitter production, as well as antioxidant protection, brain cell regeneration, circulation, and brain wave regulation. At $69.00 for a month’s supply, you may find it’s worth every penny. 

Mind Lab Pro contains two other ingredients besides L-theanine for brain regeneration: lion’s mane extract and phosphatidylserine. While lion’s mane extract increases levels of certain growth factors that act on neural stem cells, phosphatidylserine transports vital molecules through brain cells for their development and repair [13] [14]. 

NooCube

NooCube is a simpler formulation of seven ingredients and costs $59.99 for a 60-capsule bottle. The focus of NooCube is on neurotransmitter support, including acetylcholine. This is the main neurotransmitter in cognition, and therefore functions such as memory retrieval. 

One ingredient included for an acetylcholine boost is alpha glycerylphosphorylcholine (Alpha GPC). Alpha GPC is a little-known, underappreciated nootropic that can even improve memory and overall cognition in people with dementia. In fact, researchers described it as potent enough to inhibit the effects of scopolamine, a “memory-wiping” drug [15]. 

Qualia Mind

Qualia Mind aims to be everything you need in a nootropic: neurotransmitter support, antioxidant defense, cell regeneration support, a circulation boost, and aid for cellular energy production. Qualia Mind is $5.41 per seven-pill dose, as its comprehensive ingredient list makes higher doses necessary. 

Some ingredients in Qualia Mind have different effects on the same pathway. For example, tyrosine is the amino acid precursor to dopamine, while acetyl-l-carnitine can increase counts of the D1 dopamine receptors. Acetyl-l-carnitine protects dopaminergic brain cells from damage and indirectly assists by increasing cellular energy production [16]. 

Brain Pill

Brain Pill is a great all-rounder rich in dopamine-boosting ingredients, along with others to soothe inflammation, increase acetylcholine, and support brain cell regeneration. The Brain Pill supplement is $89.95 per 60-capsule bottle, costing around $3 per daily dose. 

One of Brain Pill’s ingredients is ginkgo biloba, one of the best nootropics for memory as you age. Ginkgo can boost cerebral blood flow and improve memory as a result. These benefits can even reach people with mild Alzheimer’s disease, a point where extensive damage has already been done [17]. 

L-Theanine and Caffeine

L-theanine and caffeine have opposing effects in some ways. While caffeine is a fast-acting stimulant, L-theanine has relaxing properties. Caffeine improves cognitive performance in the short term, while the effects of L-theanine can take longer, with some building up over time.

Can I Stack L-Theanine Supplements and Caffeine?

Yes, you can. When you drink green tea, you are essentially stacking L-theanine and caffeine, but at lower doses. Some nootropic supplements contain higher amounts of both, as they have differing benefits. The combined effects of L-theanine and caffeine stimulation have synergistic (multiplying) benefits on attention, cognition, and mood [5].

It is important to avoid falling into an excessive caffeine intake, even though caffeine improves cognitive performance quite rapidly. The overstimulating effects of constant coffee may leave you feeling burned out and compromise sleep quality. As L-theanine and caffeine appear together in green tea formulations, a nootropic supplement may be best. 

FAQ

What are the most important things we need to know about L-theanine?

What Does L-Theanine Do for the Brain? 

L-theanine inhibits the actions of glutamate while increasing GABA and dopamine. Reducing glutamate activity protects the brain cells from being overstimulated to death. Its supportive actions on other neurotransmitters may improve sleep, mood, motivation, and focus [3]. 

Can You Lose Weight on L-Theanine?

There isn’t enough evidence that L-theanine helps with weight loss. Only laboratory research suggests that L-theanine has fat-burning benefits, and this is yet to be replicated in a double-blind placebo-controlled clinical trial. However, if you are prone to emotional eating, you may lose weight from its stress-relieving properties [6]. 

What Happens if You Take Too Much L-Theanine?

It is unclear as to what dose of L-theanine is too much. The U.S. Food and Drug Administration (FDA) suggests that you consume no more than 1200 mg per day. This is because the 90th percentile for L-theanine intake is roughly 1200 mg, and is just to be on the safe side [18]. 

What Is the Best Time To Drink L-Theanine? 

The best time to drink L-theanine is when you are sitting down to mental work or before bed. This is because its effects on alpha brain waves provide a relaxed yet alert feeling that won’t overstimulate you or impair sleep at night. 

How Long Does It Take for L-Theanine To Start Working?

Clinical studies show that L-theanine can start working soon after just one dose. It can reach the brain in 40 minutes after reaching the intestines [5]. 

Conclusion 

L-theanine is a lesser-known amino acid found in green tea formulations, but may go a long way in improving your neurological health—and possibly metabolic health.

Its health benefits originate from an increase in the neurotransmitters GABA, serotonin, and dopamine; alongside a boost to calming alpha brain waves. These effects translate to improved objective sleep quality, better cognitive functions such as memory and focus, lower blood pressure, and a faster immune response. 

References:

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9. Kamath, Arati B et al. “Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses.” Proceedings of the National Academy of Sciences of the United States of America vol. 100,10 (2003): 6009-14. doi:10.1073/pnas.1035603100 
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