Takeaways
- L-theanine is generally safe with mild side effects
- Common effects include headaches and digestive issues
- Dosage and individual factors influence side effects
- Long-term use may lead to tolerance in some people
- Consult a doctor before use, especially if on medications
- Natural alternatives exist for those sensitive to L-theanine
Understanding L-Theanine
L-theanine, an amino acid present in tea leaves, is becoming a popular supplement.[1] People use it to manage stress and enhance focus.[2] Its structure resembles glutamate, a chemical in the brain.[3] This similarity allows L-theanine to influence brain activity.[4]
L-theanine affects the brain by influencing various processes.[5] It easily passes through the blood-brain barrier.[6] Once in the brain, it interacts with neurotransmitters, the chemicals that relay signals between brain cells.[7] L-theanine primarily affects GABA, serotonin, and dopamine.[8]
GABA is a neurotransmitter that promotes calmness.[9] L-theanine can amplify GABA’s effects, potentially explaining the relaxed feeling some experience after taking it.[10] Serotonin and dopamine influence mood and focus.[11] L-theanine’s impact on these chemicals may lead to improved mental well-being.[12]
L-theanine is generally well-tolerated, and side effects are usually minor.[13] However, like any supplement, it might cause unwanted effects in some people. Knowing about these potential issues can assist in making informed decisions about its use.
How L-Theanine Works in the Body
Absorption and Metabolism
After taking L-theanine, the body quickly absorbs it into the bloodstream via the small intestine.[14] It then circulates throughout the body. L-theanine can reach the brain within approximately 30 minutes.[15]
The body processes L-theanine efficiently.[16] It breaks it down into smaller compounds, which are then eliminated through urine. This process is relatively rapid. Most L-theanine is cleared from the body within 24 hours.[17]
Due to its rapid processing, the effects of L-theanine are not long-lasting.[18] This is why some individuals take multiple doses during the day. It also means that L-theanine does not accumulate in the body over time.[19]
Interaction with Neurotransmitters
The primary effects of L-theanine stem from its interactions with brain chemicals.[20] It has an influence on several neurotransmitters. Each interaction contributes to the overall impact of L-theanine.
GABA is a key target for L-theanine. L-theanine can increase GABA activity, leading to feelings of calm and relaxation.[21] This is similar to how some anti-anxiety medications function.[22]
L-theanine also affects dopamine and serotonin, which are neurotransmitters related to mood and focus.[23] By increasing their levels, L-theanine may improve mental state, which could explain reports of improved concentration and mood.[24]
Here’s a breakdown of how L-theanine affects different neurotransmitters:
| Neurotransmitter | Effect of L-theanine |
|---|---|
| GABA | Increases activity |
| Dopamine | May increase levels |
| Serotonin | May increase levels |
| Glutamate | May decrease activity |
These interactions help to explain many of the benefits people report from using L-theanine. They also help us understand potential side effects, since changes in brain chemistry can produce varied results for different individuals.
Common Side Effects of L-Theanine
Although L-theanine is generally considered safe, some users do experience side effects.[25] These are usually mild and temporary. Being aware of what to expect can help you determine if L-theanine is suitable for you.
Common side effects of L-theanine can include:
- Headaches
- Dizziness
- Digestive issues
- Changes in sleep patterns
- Mild anxiety
Most people who experience side effects find them manageable and that they often lessen with continued use.[26] If side effects persist, consulting with a healthcare provider is recommended.
Headaches and Dizziness
Some users of L-theanine report headaches or dizziness.[27] These symptoms are generally mild and often appear when starting L-theanine or when changing the dosage.[28]
Headaches might occur because L-theanine has an impact on brain chemicals.[29] Usually as the body adjusts, these headaches tend to subside. Dizziness might result from L-theanine’s calming properties, which can make some people feel slightly off-balance.[30]
To minimize these effects, start with a low dose and increase it gradually over time.[31] This allows your body to adapt. If headaches or dizziness persist, consider lowering your dose or stopping use.
Gastrointestinal Issues
L-theanine can occasionally cause digestive discomfort, including nausea, stomach pain, or diarrhea.[32] These effects are usually mild and do not last long.[33]
Digestive issues can occur because L-theanine is a new substance for the body.[34] Your digestive system requires time to adjust. Taking L-theanine with food can help to reduce these effects.[35]
If you have ongoing digestive problems, try reducing your dose. You can also divide your daily amount into smaller doses throughout the day. This can be easier on your stomach.
Changes in Sleep Patterns
L-theanine can affect sleep in different ways.[36] Some find that it helps them sleep better, while others might experience sleep disturbances.[37] These effects are probably due to L-theanine’s influence on brain chemicals.
For some individuals, L-theanine can promote relaxation and improve sleep quality.[38] It might help you fall asleep faster or sleep more deeply. However, others find that it makes them more alert, which could make it more difficult to fall asleep.[39]
If L-theanine affects your sleep, consider changing the time when you take it. Taking it earlier in the day could prevent nighttime issues. Alternatively, taking it before bed may improve sleep for some individuals.
Rare but Serious Side Effects
While rare, some people experience more severe reactions to L-theanine.[40] These side effects require medical attention. If you notice any unusual symptoms, stop taking L-theanine and seek medical advice.
Allergic Reactions
Allergic reactions to L-theanine are very uncommon; however, they can occur. Indications of an allergic reaction might include:
- Skin rash or hives
- Itching
- Swelling, especially of the face, tongue, or throat
- Difficulty breathing
- Severe dizziness
If you experience these symptoms after taking L-theanine, seek immediate medical assistance. Allergic reactions can be serious and require prompt treatment.
Interactions with Medications
L-theanine might interact with certain medications.[41] These interactions could worsen side effects or reduce the effectiveness of the drugs.[42] It is essential to consult a healthcare provider before using L-theanine with other medications.
Some medications that may interact with L-theanine include:
| Medication Type | Potential Interaction |
|---|---|
| Blood pressure drugs | May enhance effects, leading to low blood pressure |
| Stimulants | Might counteract stimulant effects |
| Sedatives | Could increase sedation |
| GABA-affecting drugs | May amplify effects on GABA system |
This list is not exhaustive. Always inform your doctor about all supplements you are taking. They can advise you about potential interactions and adjust treatment as necessary.
Factors Influencing L-Theanine Side Effects
Several factors can influence how L-theanine affects a person. Understanding these factors can help in anticipating and managing potential side effects.
Dosage Considerations
The amount of L-theanine you take is a significant factor in the occurrence of side effects.[43] Higher doses generally increase the risk of adverse effects.[44] Most studies use doses ranging from 100 to 400 mg per day.[45]
Starting with a low dose can help to minimize side effects.[46] You can gradually increase the amount if needed. This approach allows your body to adjust slowly. It also helps you to find the lowest effective dose for your particular needs.
Some individuals might need higher doses to achieve certain effects. However, this increases the risk of side effects. Always consult a healthcare provider before taking high doses of any supplement.
Individual Sensitivity
People react differently to L-theanine. What works well for one person might cause side effects in another. Several factors contribute to individual sensitivity:
- Genetics
- Overall health
- Body weight
- Caffeine intake
- Stress levels
Some people are naturally more sensitive to supplements.[47] They might experience effects even from small doses, while others might need larger amounts to notice any impact. Knowing your body’s usual reactions to supplements can guide your L-theanine use.
Form of L-Theanine
L-theanine is available in various forms, such as pills, powders, and teas. The form you choose can affect how your body processes it, which, in turn, can influence side effects.[48]
Supplements often contain pure L-theanine.[49] They provide a consistent, measured dose. Teas contain L-theanine naturally but in varying amounts.[50] They also contain other compounds that might interact with L-theanine.
Some people find that natural sources, like green tea, cause fewer side effects, while others prefer the precision of supplements. Experiment to determine what works best for you. Remember that teas also contain caffeine, which can impact L-theanine’s effects.[51]
Managing L-Theanine Side Effects
If you experience side effects from L-theanine, there are several strategies that may help. These approaches are aimed at reducing discomfort while maintaining the benefits.
Adjusting Dosage
Finding the right dose is often the first step in managing side effects.[52] Start with the lowest recommended dose, typically around 100-200 mg per day.[53] Observe how your body responds.
If you do not experience benefits, slowly increase the dose over several weeks.[54] Stop increasing when you achieve the desired effects or encounter side effects. If side effects occur, reduce the dose slightly.
Remember, more is not always better. The goal is to find the lowest dose that provides benefits without causing side effects. This balance varies from person to person.
Timing of Consumption
The timing of when you take L-theanine can affect its impact. Some find that morning doses work best, while others prefer evening use. Experiment with timing to see what suits you best.
For sleep improvement, taking L-theanine 30-60 minutes before bedtime might be helpful. If you are using it for daytime focus, morning or early afternoon doses are common.
If you experience digestive issues, try taking L-theanine with food. This can help to reduce stomach discomfort. Dividing your daily dose into smaller portions can also help.
Combining with Other Supplements
L-theanine is often combined with other supplements. This can enhance the benefits but can also affect the side effects. Common combinations include:
- L-theanine and caffeine
- L-theanine and melatonin
- L-theanine and B-vitamins
Each combination can have unique effects. Caffeine might counteract L-theanine’s calming effects, while melatonin could enhance sleep benefits, and B-vitamins might support overall brain function.
Be cautious when combining supplements. Start with low doses of each, and monitor how you feel and adjust as needed. Always consult a healthcare provider before combining supplements, especially if you are taking medications.
Long-Term Use and Potential Risks
Many people use L-theanine regularly without experiencing issues. However, long-term use raises some questions. Let’s explore potential concerns with extended L-theanine supplementation.
Tolerance and Dependence
Some users report developing a tolerance to L-theanine over time. This means that they need higher doses to achieve the same effects. Tolerance is more common with daily, high-dose use.
There is limited research on L-theanine tolerance. It is unclear how quickly it develops or if it affects everyone. To avoid potential tolerance:
- Take breaks from L-theanine use
- Cycle between different doses
- Use the lowest effective dose
Dependence on L-theanine is rare. Unlike some drugs, L-theanine does not cause physical addiction. However, some people might develop a psychological reliance and feel that they cannot relax without it.
If you are concerned about dependence, try taking regular breaks. This can help you assess L-theanine’s true impact on your well-being.
Cumulative Effects
Long-term L-theanine use might have cumulative effects, which could be positive or negative. Current research does not indicate significant long-term risks; however, studies on extended use are limited.
Potential long-term benefits might include:
- Improved stress management
- Better sleep quality
- Enhanced cognitive function
Possible concerns with long-term use include:
- Changes in neurotransmitter balance
- Interactions with medications over time
- Unknown effects on brain chemistry
To minimize potential risks, consider taking periodic breaks from L-theanine. This allows your body to return to its baseline. It also helps you reassess L-theanine’s effects on your health.
Regular check-ins with a healthcare provider are wise for long-term users. They can monitor your health and adjust recommendations as needed.
Special Populations and L-Theanine
L-theanine affects different groups of people in unique ways. Age, health status, and life stage can all influence its impact. Let’s explore how L-theanine might affect specific populations.
Pregnant and Breastfeeding Women
Research on L-theanine during pregnancy and breastfeeding is limited. Most experts advise caution as the effects on fetal development and infants are not well-studied.
Pregnant women naturally consume some L-theanine through tea, suggesting that low doses might be safe. However, supplement doses are often much higher, and these higher amounts lack safety data for use during pregnancy.
Breastfeeding mothers should also be cautious because L-theanine can pass into breast milk. Its effects on nursing infants are unknown. If you are pregnant or breastfeeding, consult your doctor before using L-theanine supplements.
Children and Adolescents
L-theanine use in children and teens is an area of growing interest. Some studies suggest it might help with attention and sleep; however, research is still in the early stages.
Children’s developing brains might respond differently to L-theanine. What is safe for adults may not be appropriate for children, and dosage is a particular concern as children’s smaller bodies process substances differently.
If you are considering L-theanine for a child, always consult a pediatrician first. They can provide guidance based on the child’s specific needs and health status.
Elderly Individuals
Older adults might benefit from L-theanine’s calming effects as it could help with sleep issues or anxiety that is common in this age group. However, aging bodies process substances differently.
Elderly individuals often take multiple medications which increases the risk of interactions with L-theanine. Changes in kidney and liver function that occur with age can also affect L-theanine processing.
Older adults should start with low doses of L-theanine and monitor closely for side effects. Regular check-ins with a doctor are important to ensure L-theanine use remains safe and effective.
Alternatives to L-Theanine
While L-theanine is effective for many, it is not the only option. Several alternatives can provide similar benefits and might be preferred by those who are sensitive to L-theanine.
Natural Alternatives
Many natural substances offer calming effects similar to L-theanine. These include:
- Chamomile
- Lavender
- Lemon balm
- Passionflower
- Valerian root
These herbs can be consumed as teas, supplements, or essential oils. Each has its own set of effects and potential side effects. Research their specific properties before use.
Some foods also contain compounds that promote relaxation. These include:
- Tart cherries (contain melatonin)
- Kiwi fruit (may improve sleep quality)
- Fatty fish (rich in omega-3s, which may reduce anxiety)
- Dark chocolate (contains serotonin-boosting compounds)
Incorporating these foods into your diet might provide gentle calming effects.
Lifestyle Changes
Many lifestyle adjustments can promote relaxation and focus. These natural approaches avoid the need for supplements. Consider trying:
- Regular exercise
- Meditation or mindfulness practices
- Breathing exercises
- Improved sleep hygiene
- Stress management techniques
- Reduced caffeine intake
- Increased exposure to nature
These methods often have additional health benefits beyond stress reduction and can be used alone or alongside the careful use of supplements.
When to Consult a Healthcare Provider
While L-theanine is generally safe, certain situations warrant professional advice. Knowing when to seek help can ensure safe and effective L-theanine use.
Consult a healthcare provider before starting L-theanine if you:
- Take any medications
- Have existing health conditions
- Are pregnant or breastfeeding
- Plan to give L-theanine to a child
- Have a history of mental health issues
During L-theanine use, seek medical attention if you experience:
- Severe headaches
- Persistent digestive issues
- Unusual mood changes
- Allergic reaction symptoms
- Any unexpected or concerning effects
Regular check-ins with a healthcare provider are wise for long-term L-theanine users. They can monitor your health and adjust recommendations as needed.
Remember, a healthcare provider can offer personalized advice. They consider your overall health when making recommendations. This approach is safer than relying solely on general information.
FAQ: Common Questions About L-Theanine Side Effects
Can L-theanine cause anxiety?
Is it safe to take L-theanine daily?
Does L-theanine interact with caffeine?
Can L-theanine lead to weight gain?
How long do L-theanine side effects last?
Is it possible to overdose on L-theanine?
Conclusion
L-theanine offers potential benefits for many, helping with relaxation, focus, and sleep quality. However, like any supplement, it has potential risks. Understanding these potential side effects helps you to make informed decisions about its use.
Most L-theanine side effects are mild and temporary. Common issues include headaches, digestive discomfort, and changes in sleep patterns. These often resolve as your body adjusts to the supplement. Starting with a low dose and increasing gradually can help to minimize side effects.
Individual factors play a major role in L-theanine’s effects. Your body chemistry, overall health, and any other supplements or medications you take can all influence how you respond to L-theanine. This is why personalized advice from a healthcare provider is so important.
Long-term use of L-theanine raises some questions. While current research suggests it is generally safe, more studies are needed on extended use. Taking breaks from L-theanine use can help prevent potential tolerance and allow you to reassess its effects.
For those who experience unwanted effects from L-theanine, alternatives exist. Natural herbs, dietary changes, and lifestyle adjustments can offer similar benefits. These options might be preferable for some individuals, especially those who are sensitive to L-theanine.
Remember, supplements are not regulated as strictly as medications. The quality and purity can vary between products. Choose reputable brands and consider third-party tested supplements for added safety.
Ultimately, L-theanine can be a helpful tool for many people. By understanding its potential side effects and using it responsibly, you can maximize its benefits while minimizing risks. Always prioritize your health and well-being and do not hesitate to seek professional advice when needed.
L-theanine is indeed a non-protein amino acid found primarily in tea leaves, particularly green tea. It has gained attention for its potential cognitive and relaxation benefits and is therefore being marketed as a supplement.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
L-theanine is often used for its purported anxiolytic (stress-reducing) and nootropic (cognition-enhancing) properties, although more research is needed to fully validate these claims.
L-theanine and glutamate share a structural similarity, though they have different functions in the brain. This resemblance might contribute to L-theanine’s interactions with glutamate receptors.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Due to its structural similarity to glutamate, L-theanine can interact with glutamate receptors and other neurochemical systems in the brain. This interaction is thought to mediate its effects on mood, focus, and relaxation.
Source: “The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent” https://pubmed.ncbi.nlm.nih.gov/17182482/
L-theanine is known to interact with various brain processes, particularly those involving neurotransmitter activity and brainwave patterns. It is understood to affect multiple brain systems simultaneously.
Source: “Functional roles of taurine, L-theanine, L-citrulline, and betaine during heat stress in poultry” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8908636/
L-theanine has been demonstrated to effectively cross the blood-brain barrier. This ability allows it to directly influence the brain’s neurotransmitter systems and produce its purported effects.
Source: “L-theanine attenuates nicotine reward and withdrawal signs in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10204724/
L-theanine is understood to interact with various neurotransmitter systems in the brain, influencing their activity. This interaction is thought to be the primary mechanism behind its effects on mood, focus, and relaxation.
Source: “l-Theanine Prevents Long-Term Affective and Cognitive Side Effects of Adolescent Δ-9-Tetrahydrocannabinol Exposure and Blocks Associated Molecular and Neuronal Abnormalities in the Mesocorticolimbic Circuitry” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7842745/
Studies suggest that L-theanine primarily interacts with GABAergic, serotonergic, and dopaminergic neurotransmitter systems. This interaction is considered the main mechanism of action. Although studies suggest L-theanine’s effects on serotonin and dopamine are moderate.
Source: “L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9014247/
GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter that reduces neuronal excitability, promoting relaxation, and reducing anxiety.
Source: “Relationship between the GABA Pathway and Signaling of Other Regulatory Molecules” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11476557/
Studies suggest that L-theanine can interact with GABA receptors and increase its inhibitory effects. This effect is thought to be one of the primary reasons why people feel relaxed after consuming L-theanine.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Serotonin is a neurotransmitter that plays a key role in regulating mood, sleep, and appetite. Dopamine is involved in reward, motivation, and focus. Both neurotransmitters are very important for mental well-being.
Source: “Emerging Roles for Serotonin in Regulating Metabolism: New Implications for an Ancient Molecule” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6624793/
L-theanine’s influence on serotonin and dopamine is believed to improve mood and focus, but more research is needed to fully understand these effects. While there is some supporting evidence, the extent of L-theanine’s impact on these neurotransmitter levels requires further study.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
L-theanine has been shown to be well-tolerated in most people. Side effects are typically mild and uncommon, such as headaches or gastrointestinal discomfort. It is important to note that individual reactions may vary.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
L-theanine is absorbed relatively quickly through the intestinal lining into the bloodstream, where it begins circulating throughout the body.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Studies have demonstrated that L-theanine can be detected in the brain within approximately 30 minutes of ingestion. This rapid absorption and transport allows it to exert its effects relatively quickly.
Source: “L-theanine attenuates nicotine reward and withdrawal signs in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10204724/
L-theanine is rapidly metabolized and cleared from the body, which accounts for its generally short-lived effects.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Due to its relatively fast metabolism, L-theanine is largely cleared from the body within 24 hours, and mostly through the urine.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
The relatively rapid metabolism and elimination of L-theanine lead to its effects being short-lived. This explains why people take multiple doses throughout the day to maintain its benefits.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Due to the rapid metabolism and clearance of L-theanine, it is not expected to accumulate in the body with regular use. This is a key point for its safety.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
The interactions with the brain’s neurotransmitter systems is understood to be the primary driver of L-theanine’s effects on mood, focus, and relaxation.
Source: “l-Theanine Prevents Long-Term Affective and Cognitive Side Effects of Adolescent Δ-9-Tetrahydrocannabinol Exposure and Blocks Associated Molecular and Neuronal Abnormalities in the Mesocorticolimbic Circuitry” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7842745/
L-theanine can interact with GABA receptors and increase its inhibitory effects, which can lead to feelings of calm and relaxation.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Some anti-anxiety medications work by enhancing GABAergic activity in the brain, which is similar to how L-theanine is thought to work.
Source: “Effects of Drugs and Excipients on Hydration Status” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6470661/
Studies suggest that L-theanine can influence the levels and activity of dopamine and serotonin. These neurotransmitters play a crucial role in mood and focus regulation.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
The impact of L-theanine on serotonin and dopamine levels is not fully elucidated. More research is needed to confirm the extent of this impact and its direct influence on mental state.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
While L-theanine is known to be well-tolerated, some individuals may experience side effects such as headache or digestive issues. It is important to note that these side effects are typically mild and temporary.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Most of the side effects, if they do occur, are mild, manageable and tend to lessen with time, as the body adapts to the supplement.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Some individuals report mild side effects such as headaches and dizziness, especially when first starting L-theanine or with dosage changes.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Side effects like headaches and dizziness are generally mild and tend to occur more frequently during the initial phase of L-theanine use or with changes in dosage.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
L-theanine’s interactions with neurotransmitters could potentially trigger headaches in some individuals, but this is not a well established side effect and requires more study.
The mechanisms by which L-theanine causes dizziness are not well understood, but may be due to its effects on neurotransmitters and overall calmness.
Starting with a low dose and gradually increasing it allows your body to adjust and can help to minimize any potential side effects.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
While relatively uncommon, some individuals might experience mild digestive discomfort, including nausea, stomach pain or diarrhea after consuming L-theanine.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
These gastrointestinal side effects are usually mild and tend to resolve without any intervention.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Digestive issues could occur as the body adjusts to a new supplement such as L-theanine, which might affect the digestive system in some individuals.
Consuming L-theanine with food might help in reducing digestive issues and discomfort.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
L-theanine can affect sleep patterns differently in individuals. Some people find it helps improve sleep quality, while others report sleep disturbances.
Source: “Effect of Alpha-S1-Casein Tryptic Hydrolysate and L-Theanine on Poor Sleep Quality: A Double Blind, Randomized Placebo-Controlled Crossover Trial” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8838692/
L-theanine may promote sleep quality in some people, but some individuals may find that it affects sleep negatively, causing sleep disturbances or restlessness.
Source: “Effect of Alpha-S1-Casein Tryptic Hydrolysate and L-Theanine on Poor Sleep Quality: A Double Blind, Randomized Placebo-Controlled Crossover Trial” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8838692/
L-theanine can promote relaxation and improve sleep by enhancing GABA activity and reducing stress.
Source: “Effect of Alpha-S1-Casein Tryptic Hydrolysate and L-Theanine on Poor Sleep Quality: A Double Blind, Randomized Placebo-Controlled Crossover Trial” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8838692/
Some individuals may find that L-theanine’s effects make them more alert and therefore more difficult to fall asleep. This effect is paradoxical and may be due to the way L-theanine interacts with various brain systems.
Source: “L-theanine attenuates nicotine reward and withdrawal signs in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10204724/
Although rare, more severe reactions can happen with L-theanine. If you notice any unusual symptoms, you should stop taking L-theanine and seek medical attention.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
L-theanine may interact with various medications, therefore consult with your healthcare provider before using L-theanine with other medications.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Medication interactions with supplements such as L-theanine can potentially cause harmful side effects or interfere with a medication’s therapeutic effects.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
The amount of L-theanine you consume significantly affects the potential for side effects, with higher doses increasing the risk.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Taking higher doses of L-theanine can increase the likelihood of experiencing adverse side effects, highlighting the importance of taking an appropriate dose.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Most studies of L-theanine use dosages ranging between 100 mg and 400 mg per day, which are considered the general recommended dosages.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Starting with a lower dose of L-theanine can help to minimize any potential adverse side effects, as the body slowly adapts to the supplement.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
Individual sensitivity to supplements varies widely depending on various genetic and physiological factors, which can lead to different responses.
The form of the supplement can impact absorption rate, bioavailability, and metabolism, which can lead to differences in side effects experienced.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
L-theanine supplements often contain pure L-theanine as a single active ingredient, which allows for a more precise dosage.
Tea, especially green tea, contains L-theanine, however, the amount can vary based on factors including the type of tea and brewing conditions.
Source: “L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11214244/
The caffeine content in teas can counteract L-theanine’s calming effects. Caffeine can also enhance focus and alertness.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Finding the right dose is a crucial step in managing potential side effects. It allows the individual to receive the benefits without experiencing adverse effects.
It is generally recommended to start with the lowest recommended dose (between 100 and 200 mg) to assess individual tolerance.
Source: “Goals in Nutrition Science 2020-2025” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923694/
Gradually increasing the dose over weeks allows your body to adjust. This will help to find the lowest effective dose while minimizing any potential side effects.
