L-theanine has fantastic healing properties, according to peer-reviewed studies. They range from detox to better sleep quality, weight loss and even support cancer treatment. Although naturally occurring in tea, the functional food additive should also be taken with some precaution in supplement form.
This article is a simple guide to the key effects and uses of the compound, with recommendations to supplements and how best to use them.
Key Takeaways: L-Theanine Weight Loss and Memory Boost
- L-theanine is a unique amino acid compound found in tea plants.
- Its health benefits have been recognized since ancient times in Japan and China.
- Scientific evidence shows that it can prevent and improve certain diseases or health problems, as well as improve cognitive function and reduce stress.
- L-theanine is generally recognized as safe but should not be taken by pregnant or lactating women or children.
- There are a variety of l-theanine supplements available.
L-Theanine: Overview
See below for a straightforward summary of what L-theanine is and how it could be effective in weight loss.
What Is It?
L-theanine is a naturally occurring compound from the camellia sinensis plant, or the tea plant. It is commonly found in green and black tea, as well as some mushrooms.
Specifically, it is an amino acid, made of essential elements that combine to form proteins. They are highly important for many of the body’s vital functions.
Amino acids are not produced in the body and have to be consumed through food, drinks, or an L-theanine supplement.
How Does It Work?
L-theanine has many qualities that may be highly advantageous to health. The tumor reducing, anti-inflammatory, antimicrobial, and antioxidant properties found in tea, due to its L-theanine content, are key to these benefits.
Inflammation is an outcome of many health problems, such as diabetes, high blood pressure, cancer, and arthritis. Therefore, green tea’s generalized anti-inflammatory effects may have benefits for all of these conditions.
The antioxidant properties of green tea include the ability to limit the number of free radicals in the body and increase the activity of antioxidant enzymes, helping to regulate cell development. This gives a detoxing effect and supports disease prevention.
For these reasons, L-theanine in green tea is also beneficial for cardiovascular diseases, obesity, and oral health problems [1].
L-theanine impacts neurological functioning because it can cross the blood-brain barrier and regulate hormones in the brain, positively impacting brain waves. This influences the central nervous system, reducing subjective stress, increasing subjective alertness, and enhancing mental focus [2].
Does L-Theanine Help With Weight Loss?
L-theanine is known for its anti-obesity effects, especially when combined with other ingredients. Green tea catechins and caffeine, which are also consumed when drinking green tea, are believed to enhance energy and boost metabolism—qualities generally associated with weight loss. However, peer-reviewed studies suggest this is not the main reason tea may be effective in weight loss [3].
In fact, green tea can alter digestive enzymes to reduce fat accumulation, which may be why it stops body weight increase. It can also decrease blood pressure and lowers cholesterol [1].
Dieticians suggest that green tea can also support weight loss for a more simple reason—drinking a cup of hot tea before a meal and staying hydrated can act as an appetite suppressant and lead to healthier food choices. If weight loss is important to you, talk with your dietician about the benefits of green tea.
L-theanine causes the savory flavor in green tea, which can reduce your appetite and essentially help you lose weight. The compound is also quite a powerful stress reducer and sleep aid, which are factors that contribute to weight loss as well [4].
L-Theanine Uses
L-theanine has been shown to have many other benefits to health, primarily:
- Boosting cognitive function.
- Relieving stress and anxiety.
- Improving immunity.
- Increasing focus.
- Enhancing treatment for cancer patients.
- Possibly reducing the risk of Alzheimer’s disease.
Boosts Cognitive Function
The calming effects of L-theanine are said to improve brain function. In a double-blind placebo-controlled clinical trial of older people supplemented with L-theanine for 12 weeks, memory and reaction time improved during the period of the clinical trial [5].
This is likely due to the effect that L-theanine has on brain waves. Although it is thought that caffeine improves cognitive performance, research suggests that caffeine intake \ actually reduces memory capacity. It is the mood-enhancing effect of L-theanine, its impact on objective sleep quality and wakefulness, that is responsible for the difference in executive function.
Relieves Stress and Anxiety
Evidence shows the de-stressing effects of low caffeinated green tea consumption. Tests with animals where physical and psychological stresses were created then stress-related symptoms treated with L-theanine have shown favorable physiological stress responses [6].
This is because L-theanine has a direct effect on the brain. In another placebo-controlled clinical trial, L-theanine was shown to significantly increase alpha brain waves, which promotes alert relaxation without making you sleepy. This is also known as subjective wakefulness [7].
Stress caused by schizophrenia and schizoaffective disorder has also been examined in its relationship with L-theanine.
In a double-blind placebo-controlled trial, 60 schizoaffective disorder patients participated in an 8-week trial. They received 400mg per day of L-theanine with their usual drug administration. Compared with the placebo group, the L-theanine group was associated with reducing anxiety [8].
According to a review of the evidence by academic research institutions, anxiety symptoms caused by all mental health problems can be helped safely with 200–400mg of L-theanine per day. This is thanks to its stimulation of alpha brain waves and effect on the central nervous system to promote relaxation [9].
Does L-Theanine have an effect on depression?
May Improve Immunity
Green tea has been shown to support the immune system in randomized controlled clinical trials.
In a medical exploration with rats, L-theanine’s results on immune function were positive [10].
This is because of L-theanine’s effect on the brain, including in the pituitary gland, impacting hormones. It also helps the body produce anti-inflammatory cytokines, a type of protein that can reduce inflammation caused by illness [11].
Increases Focus
A peer-reviewed study about L-theanine and caffeine stimulation to assess the possible treatment of attention deficit hyperactivity disorder showed that L-theanine boosts focus, but caffeine does not. Though it is believed caffeine improves cognitive performance, it has a negative impact on memory and healthy sleep.
Attention deficit hyperactivity disorder is characterized by a lack of attention and ability to focus, as well as impulsive behavior. Alpha activity is known to play an essential role in improving attention span and cognitive performance [12].
The effects of L-theanine, even at levels that are realistic to normal intake from drinking tea daily, increases subjective alertness and contributes to a naturally enhanced state of focus [13].
May Enhance Cancer Treatment
Drinking tea has been shown to support the treatment of cancer alongside medical interventions.
In an extensive study of 254 patients diagnosed with cancer, the group who increased their green tea consumption showed a more significant improvement than those who did not. Therefore, it was conclusive in the study that theanine enhances recovery as it increases cancer patients’ survival time due to its anticarcinogenic effects [14].
There are mixed views on the extent to which green tea can prevent cancer or support in its recovery. Further scientific research is available about how L-theanine compounds can affect the behavior of cells and prevent cancer. It is seen as a dietary supplement for general health benefits, though, as opposed to a cure [15].
May Reduce Risk of Alzheimer’s Disease
Alzeheimer’s is an inherited neurodegenerative condition whereby brain function, reactions, and memory decrease in old age to a point that severely interferes with daily life.
Research on how to prevent the condition or reduce the extent of deterioration it causes is becoming more prominent, and L-theanine has been tested for this reason.
In a 2018 review of tea drinking evidence relevant to Alezheimer’s, L-theanine is not yet a proven cure. However, with more clinical trials making this link, it could prove useful in the fight against Alzheimer’s disease [16].
L-Theanine Side Effects
L-theanine is not known to have any significant side effects, although there are a few points to consider if you are thinking of taking L-theanine.
Precautions and Warnings
The FDA classification of L-theanine is “generally recognized as safe,” which means an L-theanine supplement has no health risk if used as recommended [17].
However, there is limited research to show the effect that L-theanine may have on women who are pregnant or breastfeeding. Therefore, it is not recommended for use during pregnancy or lactation.
Animal studies whereby a higher dosage of L-theanine is administered have been associated with some liver damage due to toxicity—a general side effect of taking too much of a substance [18].
Science suggests daily doses ranging from 200 to 400 mg for up to 8 weeks are safe and have anti-stress effects [13].
Interactions
L-theanine may have a negative impact on health when combined with other pharmacological compounds [9].
Therefore, if you are on any other regular medication, it would be a good idea to inform your doctor if you are looking to start taking L-theanine supplements.
Best L-Theanine Weight Loss and Memory Boosting Nootropics
Here is a quick guide to the best brain-enhancing nootropics for memory and weight loss on the market.
Mind Lab Pro
Mind Lab Pro is a nootropic supplement that has some excellent reviews relating to its effect on mood and focus. It contains 100 mg of L-theanine alongside other plant-based enhancers and a mix of useful vitamins. The Mind Lab Pro review provides you with more detail of its results, but below is a snapshot of its pros and cons.
Pros
- Heightens attention span and focus.
- Enhances energy levels.
- Positive effect on mood.
Cons
- Relatively expensive.
- Does not help you stay awake (though it is not stimulant medication).
NooCube
Similarly, NooCube is an over-the-counter supplement containing 100 mg of L-theanine and other herbs for enhancing focus and productivity. This NooCube review will give you a balance of opinions on the effectiveness of these nootropics for memory.
Pros
- NooCube improves memory.
- Improves mood.
- Impacts focus and concentration.
Cons
- May not have as much of an effect as marketed.
Qualia Mind
Qualia Mind is a blend of amino acid, including green tea extract and vitamins, with a similar goal to the other two nootropics for motivation—to enhance cognitive performance.
Pros
- Enhances mental clarity.
- Enhances memory and focus.
- Promotes long-term brain health.
Cons
- Relatively expensive.
- It has a lot of ingredients, some of which may not be very beneficial to the brain.
FAQ
Find your key questions about L-theanine answered here.
What Does L-Theanine Do for Anxiety?
L-theanine reduces anxiety by affecting hormones and brain alpha waves. They, in turn, affect the nervous system that leads to a feeling of calm wakefulness.
L-theanine helps with restful sleep too. Its effects on objective sleep quality are known for improving mood and cognition.
How Do You Take Theanine for Anxiety?
L-theanine is from green tea catechins; therefore, you can simply just drink green tea. White and black tea also contain some of it, to a lesser extent.
Alternatively, it can be supplemented as part of a healthy diet with nootropics.
Should You Take L-Theanine at Night?
Yes, it should be fine to take it at night and may even improve sleep quality.
How Long Does It Take for L-Theanine To Start Working?
According to reviews, supplements can start working in as quickly as 20 minutes. Effects may then last up to 10 hours.
However, it would be worth considering incorporating a suitable amount of L-theanine into your dietary habits for a longer-term effect.
Conclusion
Reviews aside, the science of L-theanine is something we should know about. Eastern cultures have benefited from long-term health for millennia, which could be related to tea consumption.
Whether you want to boost and impact your cognition quickly through supplementation or are simply inspired to drink more healthy tea, L-theanine would be a great change in your diet for health promotion.
References
- Reygaert, Wanda C. “Green Tea CATECHINS: Their Use in Treating and PREVENTING Infectious Diseases.” BioMed Research International, Hindawi, 17 July 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6076941/.
- Li, Chengjian, et al. “L-Theanine Improves Immunity by Altering Th2/th1 Cytokine BALANCE, BRAIN Neurotransmitters, and Expression of Phospholipase C in RAT HEARTS.” Medical Science Monitor : International Medical Journal of Experimental and Clinical Research, International Scientific Literature, Inc., 28 Feb. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC4772912/.
- Jurgens TM;Whelan AM;Killian L;Doucette S;Kirk S;Foy E; “Green Tea for Weight Loss and Weight Maintenance in Overweight or Obese Adults.” The Cochrane Database of Systematic Reviews, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/23235664/.
- Hidese, S., Ogawa, S., Ota, M., Ishida, I., Yasukawa, Z., Ozeki, M., & Kunugi, H. (2019). Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients, 11(10), 2362. https://doi.org/10.3390/nu11102362
- Baba Y;Inagaki S;Nakagawa S;Kaneko T;Kobayashi M;Takihara T; “Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study.” Journal of Medicinal Food, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/33751906/.
- Unno K;Hara A;Nakagawa A;Iguchi K;Ohshio M;Morita A;Nakamura Y; “Anti-Stress Effects of Drinking Green Tea with Lowered Caffeine and Enriched Theanine, Epigallocatechin and Arginine on Psychosocial Stress Induced Adrenal Hypertrophy in Mice.” Phytomedicine : International Journal of Phytotherapy and Phytopharmacology, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/27765356/.
- GN;, Nobre AC;Rao A;Owen. “L-Theanine, a Natural Constituent in Tea, and Its Effect on Mental State.” Asia Pacific Journal of Clinical Nutrition, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/18296328/.
- Ritsner MS;Miodownik C;Ratner Y;Shleifer T;Mar M;Pintov L;Lerner V; “L-Theanine Relieves Positive, Activation, and Anxiety Symptoms in Patients with Schizophrenia and Schizoaffective Disorder: An 8-Week, Randomized, Double-Blind, Placebo-Controlled, 2-Center Study.” The Journal of Clinical Psychiatry, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/21208586/.
- Lopes Sakamoto F;Metzker Pereira Ribeiro R;Amador Bueno A;Oliveira Santos H; “Psychotropic Effects of l-Theanine and Its Clinical Properties: From the Management of Anxiety and Stress to a Potential Use in Schizophrenia.” Pharmacological Research, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/31412272/.
- Li, Chengjian, et al. “L-Theanine Improves Immunity by Altering Th2/th1 Cytokine BALANCE, BRAIN Neurotransmitters, and Expression of Phospholipase C in RAT HEARTS.” Medical Science Monitor : International Medical Journal of Experimental and Clinical Research, International Scientific Literature, Inc., 28 Feb. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC4772912/.
- Zhang, Jun-Ming, and Jianxiong An. “Cytokines, Inflammation, and Pain.” International Anesthesiology Clinics, U.S. National Library of Medicine, 2007, www.ncbi.nlm.nih.gov/pmc/articles/PMC2785020/.
- Kahathuduwa, Chanaka N., et al. “Effects of l-Theanine–Caffeine Combination on Sustained Attention and Inhibitory Control among Children with Adhd: A Proof-of-Concept Neuroimaging Rct.” Nature News, Nature Publishing Group, 4 Aug. 2020, www.nature.com/articles/s41598-020-70037-7.
- GN;, Nobre AC;Rao A;Owen. “L-Theanine, a Natural Constituent in Tea, and Its Effect on Mental State.” Asia Pacific Journal of Clinical Nutrition, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/18296328/.
- Zhang, Min, et al. “Green Tea Consumption Enhances Survival of Epithelial Ovarian Cancer.” Wiley Online Library, John Wiley & Sons, Ltd, 23 June 2004, onlinelibrary.wiley.com/doi/full/10.1002/ijc.20456.
- Miyata, Yasuyoshi, et al. “Anticancer Effects of Green Tea and the Underlying Molecular Mechanisms in Bladder Cancer.” Medicines (Basel, Switzerland), MDPI, 10 Aug. 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC6164790/.
- Polito, Curt Anthony, et al. “Association of Tea Consumption with Risk of Alzheimer’s Disease and ANTI-BETA-AMYLOID Effects of Tea.” Nutrients, MDPI, 22 May 2018, www.ncbi.nlm.nih.gov/pmc/articles/PMC5986534/#sec4-nutrients-10-00655title.
- “Gras Notices.” Cfsanappsexternal.fda.gov, www.cfsanappsexternal.fda.gov/scripts/fdcc/index.cfm?set=GrASNotices&id=209.
- Lopes Sakamoto F;Metzker Pereira Ribeiro R;Amador Bueno A;Oliveira Santos H; “Psychotropic Effects of l-Theanine and Its Clinical Properties: From the Management of Anxiety and Stress to a Potential Use in Schizophrenia.” Pharmacological Research, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/31412272/.
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