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Caffeine + L-Theanine

L-Theanine and Caffeine are powerful energizing compounds found in mushrooms/tea and in coffee, respectively. The benefits of using Caffeine along with L-Theanine include a significant boost in mood, enhanced memory, heightened cognitive performance, energizing effects, and improved metabolism [1] [2] [3] [4]. 


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Caffeine + L-Theanine Reviews




At a Quick Glance


Ingredients (1 capsule)

Caffeine - 100 mg
L-Theanine - 150 mg


How it Works

Binds to Adenosine Receptors [5]
Releases Catecholamines [6]
Active at GABA sites [7]
Anti-inflammatory [4]

Is Used For

Enhancing Cognitive Function [1]
Mental Focus [1]
Boosting Energy Levels [1]
Improving Mood [1]

Medical Disclaimer

Not intended to treat, diagnose, or cure any disease or ailment. Please read and fully understand the potential adverse effects before using this product. These statements have not been reviewed by the FDA and are not written by a medical professional. Please consult your doctor before using any supplements, especially if you have any medical conditions.





Benefits and Effects on Humans

Based on Available Scientific Research and Anecdotal Evidence



Used For: Efficacy
Cognitive Enhancement ★★★★★
Boosting Energy Levels ★★★★★
Improving Mood ★★★★
Enhancing Mental Focus ★★★★★
Pre-workout ★★★




How to Use

Recommended Serving Size and Application


The serving size of our Caffeine + L-Theanine capsules is 250 mg, each containing 150 mg of L-Theanine and 100 mg of Caffeine. The recommended serving size is 1-2 capsules, once to twice daily. Always start with a lower serving (1 capsule) to assess your response to the supplement.


Since this product contains Caffeine, it is not recommended to use it after midday since it may interfere with your sleeping patterns. Best taken in the morning or 30 minutes prior to exercise. Do not exceed the recommended serving size.



Evidence-Based Research



1. Summary

L-Theanine and Caffeine are two highly beneficial compounds with a long history of use in different cultures around the world. Typically, L-Theanine is used for its relaxing, calming, and stress-reducing effects, along with its powerful antioxidant benefits [2]. Caffeine, on the other hand, is used for its stimulating, energizing, and mood-boosting effects.[3] Combining the two supplements provides great benefits, all of which have been verified in studies from around the world.


L-Theanine is a fairly rare phytochemical and a non-dietary amino acid found primarily in a small number of mushrooms and in a tea plant called Camellia sinensis [8]. For thousands of years, people in the East have used strong tea as a health-promoting and calming drink. Without knowing it, they were tapping into the benefits of L-Theanine. These include its ability to help reduce stress, improve mood, enhance mental focus, boost sleep quality, and promote a healthy circulatory system through its powerful antioxidant effects.[9]

Caffeine is even better known than L-Theanine and as coffee is one of the world’s most consumed drinks, most people already have a good understanding of Caffeine’s effects. Accordingly, research shows that caffeine is energizing, stimulating, and induces noticeable improvements in mood and cognitive performance [3, 6]. Caffeine is described as a purine alkaloid and it is found predominantly in Coffea Arabica (the ‘coffee tree’), which is a dark green shrub that is indigenous to Ethiopia [10].


However, Caffeine is also a stimulant with potentially dangerous properties at high doses. It acts as a vasoconstrictor, which means it causes blood vessels to constrict and this increases blood pressure, although it also improves focus and energy [4]. A cup of coffee generally contains about 60 mg of pure caffeine and consuming more than 6 cups of coffee can be dangerous [11]. Therefore, pure caffeine needs to be used very carefully to avoid potentially negative side effects. 

The recommended serving size is 1-2 capsules of 250 mg taken once or twice daily. The side effects of too much Caffeine include nervousness, headache, tremor, spasms, palpitations, high blood pressure, insomnia, and indigestion [4]. Therefore, the recommended serving should not be exceeded.


caffeine + l-theanine for focus


2. Human Effects and Benefits


The overall benefits and effects of Caffeine + L-Theanine capsules can be summarized into three categories, namely, the benefits of L-Theanine alone, Caffeine alone, and the benefits of combining the two.


2.1. Benefits of L-Theanine


2.1.1. Powerful Antioxidant Effects:

Studies have shown that L-Theanine has protective effects on the liver due to its ability to act as a powerful antioxidant. Alcohol consumption increases the amount of toxic chemicals called ‘free-radicals’ in your body. These cause harm to your liver and other organs. In 2012, scientists showed that L-Theanine has a significant protective effect on the liver by helping your body to destroy free-radicals [12].


2.1.2. May Help Boost Mental State:

Studies have also shown that the consumption of L-Theanine significantly increases the activity in alpha-frequency brainwaves in humans [13]. Alpha brainwaves are associated with a relaxed, but alert state of mind. These effects are especially noticeable in concentrations of L-Theanine that are higher than the amount that is generally in a cup of tea, for example. Furthermore, alpha brainwave activity is thought to play an important role in attention and mental focus [13].


2.1.3. Helps to Reduce Feelings of Stress:

Human studies have shown that supplementing the diet with L-Theanine can reduce your response to stress [14]. In one study, volunteers took an L-Theanine supplement and were presented with a stressful stimulus. The results demonstrated the participants who took L-Theanine had a lower heart rate and salivary immunoglobulin (s-IgA) in comparison to those who took a placebo or not supplement at all [14]. These are critical aspects of the stress response.


2.2. Benefits of Caffeine


2.2.1. Energizing and Stimulating

Caffeine has powerful effects on the central nervous system (CNS) [15]. Through these effects, it is able to generate positive and noticeable influence on mental activity. In particular, it activates noradrenaline receptors and promotes the release of dopamine. Essentially, caffeine increases mental and physical energy while improving mental stimulation and alertness [15].

2.2.2. Improves Mood

People have known for a long time that caffeine can be used to improve mood. For instance, a single cup of coffee noticeably enhances the state of mind and feelings of well-being for many people. Numerous studies have also been conducted to evaluate the mechanism of action and the scientific soundness of these claims. Accordingly, there is now empirical evidence that Caffeine significantly helps to boost mood [16].


2.2.3. Boosts Physical Energy and May Help Maintain a Healthy Metabolism

In a recent study, the effects of Caffeine on energy levels and thermogenesis (the production of heat in the body as a result of increased metabolism) were studied. In the study, twelve healthy participants were given either Green Tea Extract, Tyrosine, or Caffeine (50 mg). Out of the three substances used, only Caffeine produced a significant increase in thermogenesis [17]. This means that Caffeine can be used to boost metabolism, physical energy, and endurance. Furthermore, this evidence suggests that people may consider using Caffeine in addition to a healthy diet as a means of promoting weight-loss due to its influence on metabolism [17].


2.3. Benefits of Using L-Theanine with Caffeine

When you take a supplement containing both Caffeine and L-Theanine, you’ll be able to experience the benefits of both these great compounds. This means you’ll feel noticeable improvements in mood, memory, and stress-reduction, while also feeling mentally stimulated and energized [1]. This is definitely one of the top supplement stacks available today!


2.3.1. Helps Mitigate Potential Negative Effects of Caffeine

Studies involving the benefits of using L-Theanine with Caffeine show a highly synergistic relationship between the two [1, 18]. In one study for example, researchers found that L-Theanine helped to reduce the vasoconstrictive (blood vessel constricting) effects of Caffeine. This means that L-Theanine may help reduce some of the potentially dangerous effects of Caffeine, especially for people with high blood pressure [18].


2.3.2. Boosts Cognitive Performance

A number of studies have researched the synergistic effects of taking both L-Theanine and Caffeine, especially for your mental state. In one such study, researchers found that taking Caffeine with L-Theanine significantly improved cognitive performance and mood, while reducing the negative influence that consuming caffeine alone has on heart-rate and blood pressure [19].

In a similar study, researchers found that taking L-Theanine with Caffeine helped to reduce the adverse effects of taking these two substances in large amounts. This means that fewer people reported experiencing headaches, which was common with high doses of L-Theanine [20]. Furthermore, the combination improved Rapid Visual Information Processing (RVIP) accuracy scores and reduced ‘mental fatigue’ ratings better than either supplement alone. These results indicate that significant improvements in cognitive performance are experienced when using a combination of L-Theanine and Caffeine [20].

caffeine for energy and focus  


3. Safety & Toxicity


3.1. Side Effects

Large servings of Caffeine can cause nervousness, headache, tremor, spasms, palpitations, high blood pressure, insomnia, and indigestion [4, 21]. Large servings of L-Theanine may cause dizziness, upset stomach, and headaches.

Caffeine may not be suitable for people with a number of ailments. This includes people with anxiety disorders, bipolar disorder, bleeding disorders, heart conditions, diabetes, epilepsy, diarrhea, glaucoma, high blood pressure, irritable bowel syndrome, or osteoporosis [4]. If you have any medical issues, please consult your doctor before using a Caffeine supplement.

Caffeine is also known to be addictive and withdrawal symptoms from prolonged caffeine use are common. Withdrawal effects may include headaches, irritability, anxiety, dry mouth, and nausea [22]. In order to avoid withdrawal symptoms, do not use high doses of Caffeine capsules for prolonged periods of time.


3.2. Overdose

Please be aware that it is possible to overdose on Caffeine. At extremely large servings, a fatal overdose is also possible, although an overdose on coffee is very unlikely. However, using pure anhydrous Caffeine increases the risk of overdosing because it is much easier to take a far greater amount. In one case study, a 39-year-old man passed away after consuming 12 grams of pure anhydrous caffeine [23].

According to research, overdose symptoms can occur at servings of 5 grams or more of Caffeine per day [21, 23]. This means that it is important to limit the serving of Caffeine + L-Theanine capsules to no more than 4 capsules per day, for healthy adults. Pregnant women are warned to reduce this amount to no greater than 200 mg per day [21].





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How We Research Our Content

Our content is written using meticulous research methods and claims are backed by links to scientific references, wherever possible. The author and editors of Liftmode's Research Team have strong academic backgrounds in microbiology, physiology, and biochemistry.

Content Updated On: January 9th, 2019



Content By:

Written By: Tristan Pelser, B.Sc. in Molecular Biology
Medically Reviewed by: Dr. Karen Vieira, PhD in Biomedical Sciences


Scientific Support and References

[1] Einöther, S. J., & Martens, V. E. (2013). Acute effects of tea consumption on attention and mood. American Journal of Clinical Nutrition, 98(6 Suppl):1700S-1708S.

[2] Lu, K., Gray, M. A., Oliver, C., Liley, D. T., Harrison, B. J., Bartholomeusz, C. F., Phan, K. L., & Nathan, P. J. (2004). The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharmacol, 19(7):457-65.

[3] Nehlig, A. (2010). Is caffeine a cognitive enhancer? J Alzheimers Dis, 20:S85-94.

[4] Temple, J. L., Bernard, C., Lipshultz, S. E., Czachor, J. D., Westphal, J. A., & Mestre, M. A. (2017). The Safety of Ingested Caffeine: A Comprehensive Review. Frontiers in Psychiatry, 8.

[5] Cornelis, M. C., El-Sohemy, A., & Campos, H. (2007). Genetic polymorphism of the adenosine A2A receptor is associated with habitual caffeine consumption. Am J Clin Nutr, 86(1):240-4.

[6] Jackman, M., Wendling, P., Friars, D., & Graham, T. E. (1996). Metabolic catecholamine, and endurance responses to caffeine during intense exercise. J Appl Physiol, 81:1658-63.

[7] Nathan, P. J., Lu, K., Gray, M., & Oliver, C. (2006). The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother, 6(2):21-30.

[8] Adhikary, R., & Mandal, V. (2017). L-theanine: A potential multifaceted natural bioactive amide as health supplement. Asian Pac J Trop Biomed, 7(9):842-848.

[9] Juneja, L. (1999). L-theanine—a unique amino acid of green tea and its relaxation effect in humans. Trends in Food Science & Technology, 10(6-7):199-204.

[10] Barone, J. J., & Roberts, H. R. (1996). Caffeine consumption. Food and Chemical Toxicology, 34(1), 119-129.

[11] Svatikova A., Covassin, N., Somers, K. R., Somers, K.  V., Soucek, F., Kara, T., & Bukartyk J. (2015). Potentiated blood pressure responses to energy drink intake in caffeine naïve healthy adults: A double-blind randomized controlled study. Journal of the American College of Cardiology, 65: A1432.

[12] Li, G., Ye, Y., Kang, J., Yao, X., Zhang, Y., Jiang, W., Gao, M., Dai, Y., Xin, Y., Wang, Q., Yin, Z., & Luo, L. (2012). L-Theanine prevents alcoholic liver injury through enhancing the antioxidant capability of hepatocytes. Food Chem Toxicol, 50(2):363-72.

[13] Nobre, A. C., Rao, A., Owen, & G. N. (2008). L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr,17 Suppl 1:167-8.

[14] Kimura, K., Ozeki, M., Juneja, L. R., Ohira, H. (2007). L-Theanine reduces psychological and physiological stress responses. Biol Psychol, 74(1):39-45.

[15] Glade, M.  J. (2010). Caffeine-Not just a stimulant. Nutrition, 26(10):932-8.

[16] Smith, A., Sutherland, D., & Christopher, G. (2005). Effects of repeated doses of caffeine on mood and performance of alert and fatigued volunteers. J Psychopharmacol, 19(6):620-6.

[17] Belza, A., Toubro, S., & Astrup, A. (2009). The effect of caffeine, green tea and tyrosine on thermogenesis and energy intake. European Journal of Clinical Nutrition, 63:57-64.

[18] Dodd, F. L., Kennedy, D. O., Riby, L. M., & Haskell-Ramsay, C. F. (2015). A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood. Psychopharmacology (Berl), 232(14):2563-76.

[19] Giesbrecht, T., Rycroft, J. A., Rowson, M. J., & De Bruin, E., A. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci, 13(6):283-90.

[20] Haskell, C.F., Kennedy, D. O., Milne, A. L., Wesnes, K. A., & Scholey, A. B. (2008). The effects of L-theanine, caffeine and their combination on cognition and mood. Biol Psychol, 77(2):113-22.

[21] Kerrigan, S., & Lindsey, T. (2005). Fatal caffeine overdose: Two case reports. Forensic Science International, 153(1):67-69.

[22] Juliano, L. M., & Griffiths, R. R. (2004). A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology, 176(1):1-29.

[23] Jabbar, S. B., & Hanly, M. G. (2013). Fatal caffeine overdose: a case report and review of literature. Am J Forensic Med Pathol, 34(4):321-4.