L-theanine, also known as theanine, is a unique substance found at high levels in tea, where it gives flavor and special health properties. In contrast, magnesium is a multifunctional, essential mineral for many processes in the body, and is found in many different foods.
Both L-theanine and magnesium may have overall effects that improve relaxation, decrease feelings of stress and anxiety, and improve sleep—at least for some individuals. To achieve these effects, some people take both.
Not much research has directly studied the effects of combining these substances. However, because they affect the brain in related but somewhat different ways, it’s possible that taking both might have an additive effect on promoting relaxation and improving resilience.
L-theanine and magnesium should be safe for most people to take together. However, be mindful of the doses of magnesium, especially if you have a significant medical condition like kidney disease.
L-theanine is an amino acid. Amino acids are the building blocks of proteins found in the foods you eat. However, L-theanine has a different structure than the other amino acids found in your diet. Scientists think its unique structure may give it certain health properties.
L-theanine at least partly works by enhancing levels of the neurotransmitter gamma-aminobutyric acid (GABA), which promotes sleep and relaxation. Higher GABA levels also increase levels of serotonin and dopamine, which enhance feelings of enjoyment and overall well-being.
L-theanine also seems to positively affect one of the body’s stress systems, the hypothalamus-pituitary-adrenal (HPA) axis.
Studies of L-theanine are limited, but some evidence supports the following possible benefits:
Provides anti-stress effects and reduces anxiety: L-theanine may improve stress-related symptoms in some people. It may also increase mental sharpness if stress is negatively affecting your ability to think clearly.
Improves sleep quality: L-theanine tends to promote relaxation, but it doesn’t make most people drowsy, unlike many other sleep aids. It may improve both sleep quality and sleep duration in some people.
Potentially decreases depressive symptoms: L-theanine impacts multiple biological pathways involved in depression. It may benefit people with clinical depression when used along with drug therapies, but more studies are needed.
Researchers have also explored other potential benefits, including improved immunity, neuroprotection, anti-inflammatory properties, blood glucose regulation, anti-cancer characteristics, and cardiovascular protection. However, much of this research needs further studies to confirm these benefits.
Magnesium helps trigger many chemical reactions in the body, including some important for nerve and muscle signaling. Among its other properties, magnesium seems to modulate GABA receptor activity. It also affects one of the body’s stress systems, the HPA axis.
Scientists have studied magnesium in many different health contexts. Results are most impressive in people who have a magnesium deficiency, but some studies have shown taking extra magnesium may be beneficial as well. Potential benefits of magnesium include:
Improving sleep quality: Magnesium may improve sleep quality and sleep duration, especially in people who haven’t been getting enough of the mineral. However, it’s unclear if supplements help everyone, including people not deficient in magnesium, sleep better. Improving depression: People with depression are more likely to have low magnesium levels, and depression is common in people with severe deficiencies. However, supplementation doesn’t always improve depression symptoms.Decreasing anxiety and perceived stress: Stress can contribute to lower magnesium levels, and lower levels of magnesium are associated with greater levels of anxiety and stress. Magnesium can also help relax tight muscles and relieve nervous tension, so supplementation may help some people with the symptoms of anxiety and stress.
Scientists have also studied the use of magnesium for high blood pressure, diabetes, asthma, osteoporosis, migraine headaches, and epilepsy. So far, these studies have mixed results.
L-theanine and magnesium may have positive effects when it comes to reducing perceived stress, decreasing anxiety, and promoting high-quality sleep. If you are looking for help in any of these areas, a combination of the two supplements might theoretically work better than taking either on its own.
People who experience a lot of stress might particularly benefit from the combination since both supplements seem to impact the body’s stress response. Stress depletes magnesium, so people with high stress levels may be particularly at risk of deficiencies. Taking L-theanine as well might enhance the anti-stress effects.
There is limited research on combined magnesium and L-theanine supplements. One study on sleep in mice looked at the differences between L-theanine alone versus L-theanine combined with magnesium. L-theanine combined with magnesium was better at decreasing the time to get to sleep and increasing the sleep duration compared to L-theanine alone. Using both supplements also improved important neurotransmitters involved in sedation, like melatonin.
Another potential benefit might be related to dosage and reducing side effects. For example, if you take L-theanine and magnesium together, you might be able to use a lower dosage of magnesium and still get a similar effect than if you were just taking magnesium alone. That might be helpful if you were experiencing side effects from magnesium, like diarrhea.
You could choose to take L-theanine and magnesium as separate supplements, but they are also available as combination products in the form of pills, powders, or chews. Sometimes the two are included in products marketed for stress support, along with other compounds like B vitamins.
You can also get L-theanine by drinking tea, which contains other compounds with additional health effects. However, if you are considering L-theanine for its calming effects, make sure to choose a tea that doesn’t contain caffeine.
Because of the relaxing properties of L-theanine and magnesium, you might consider taking them in the evening before bed. If you experience any stomach upset, you may want to take them after eating food.
Some people notice a very quick calming effect from taking a combination product. Other people might experience a slower and more subtle impact.
Note that combination products containing L-theanine and magnesium are not identical to products sold as magnesium L-threonate. That is a specific form of magnesium designed to be more readily absorbed, but it doesn’t contain L-theanine.
Dosage
The ideal dosage for L-theanine and magnesium taken together is not known. It’s often best to start with a lower dose and increase gradually if needed. Factors like your age, sex, and other medical conditions might change your ideal dosage.
L-theanine isn’t an essential nutrient, so there isn’t a minimum dose you need to have daily. From a supplement perspective, the best doses of L-theanine haven’t been established. Most studies have used doses between 100-200 milligrams (mg), and many over-the-counter (OTC) supplements are in this range. In a clinical setting, it’s been shown to be safe in doses of up to 900 mg for up to eight weeks.
For magnesium, the recommended daily allowance is 420 mg for men and 320 mg for women (age 31 and over). This should include any magnesium in the food you eat as well as any magnesium supplements you are taking. Many OTC supplements include 250-300 mg of magnesium.
For most people, it should be safe to combine L-theanine and magnesium, as both are safe at reasonable doses. The pair aren’t well studied together, but research does not indicate that taking them together would be a problem.
OTC supplements can vary in quality. Ideally, look for labeling that indicates that the product has been tested by a third party, like the U.S. Pharmacopeia (USP). Some supplements purchased through a healthcare provider may be designated as “pharmaceutical grade,” another sign of high quality.
Potential Drug Interactions
Drug interactions can make another drug you take more or less potent, and they might increase drug side effects. Because of this, it’s best to discuss your supplements with a healthcare provider who can help you make informed choices based on your specific medical needs.
Potential drug interactions for L-theanine are not well studied. However, due to L-theanine’s effect on the body, it might interact with other medications that affect the GABA system. This could increase sedation to a potentially harmful level, although that hasn’t been demonstrated.
Drugs that affect the GABA system are often used for anxiety, sedation, muscle spasms, neuropathy, or seizure prevention. These include:
Valium (diazepam)Ativan (lorazepam)Lioresal (baclofen)Dyzantil (valproate)PregabalinGabapentinAlcohol
Magnesium might decrease the absorption of certain antibiotics such as Vibramycin (doxycycline) or Cipro (ciprofloxacin), or some drugs for osteoporosis such as Fosamax (alendronate). Depending on the type, diuretics might either increase or decrease the amount of magnesium in your body. You might also need to limit medications that contain magnesium, such as antacids like Rolaids.
The U.S. Food and Drug Administration (FDA) categorizes L-theanine as “generally recognized as safe” (GRAS). Studies of L-theanine also haven’t identified any major safety problems. However, supplements like L-theanine haven’t been as well studied as drugs approved by the FDA. You should still use a reasonable approach with dosage and generally not take more than indicated on the product.
It is possible to have too much magnesium. When taken at extremely high doses, magnesium can cause symptoms such as muscle weakness, difficulty breathing, low blood pressure, and vomiting. If severe, magnesium toxicity may lead to a potentially fatal heart rhythm.
Government recommendations state that people 9 years or older should take no more than 350 mg per day of magnesium supplements. However, your total magnesium intake including foods could be higher. People with severe kidney disease may be at particular risk of magnesium toxicity and may need to avoid supplements.
It’s not known if combining L-theanine with magnesium increases their potential side effects. Since both can have a calming effect, the combination could make you less alert than desired.
L-theanine doesn’t have well-known side effects, but anecdotally some people have described headache, nausea, or jitteriness when taking it at higher doses. However, these issues might have occurred in people who were taking L-theanine supplements combined with caffeine, so it’s not clear that L-theanine was the cause.
Diarrhea, cramping, and nausea are relatively common side effects of magnesium, even at moderate doses. If you are having this issue, you might need to decrease your dose.
L-theanine is an amino acid naturally found in tea, and magnesium is a multifunctional mineral. Health supplements containing both have become popular for reducing stress, improving relaxation and sleep quality, and enhancing one’s sense of overall well-being. Both products tend to make you feel more relaxed but not overly sedated.
L-theanine is generally considered safe, but some people need to be cautious about taking extra magnesium, especially people who have kidney disease. Working with a healthcare professional is the best way to get advice about whether the combination might make sense for you.