L-Theanine Benefits and Uses
Known for helping people relax, L-theanine also has other potential health benefits, including:
Relieve anxiety and stress
Drinking a hot cup of tea can help you feel relaxed, and studies show that it not only relaxes your mind but also won't cause drowsiness.
In a review of five randomized controlled trials involving 104 participants, four trials linked L-theanine to reduced stress and anxiety in people experiencing stressful situations.
Another study published in the Journal of Clinical Psychiatry focused on people with schizophrenia or schizoaffective disorder. Researchers have found that L-theanine can reduce anxiety and improve symptoms.
increase concentration
L-theanine may help improve concentration when paired with caffeine.
A small study found that a combination of L-theanine (97 mg or mg) and caffeine (40 mg) helped a group of young adults focus better during difficult tasks. A typical cup of coffee contains 95 milligrams of caffeine.
Study participants also felt more alert and less fatigued overall.
better immunity
Some studies show that L-theanine can improve the function of the body's immune system. A study published in the journal Beverage found that L-theanine can help reduce upper respiratory tract infections.
Another study found that green tea catechins (antioxidants) and theanine were effective in preventing the flu.
Another study found that L-theanine can help improve intestinal inflammation. However, more research is needed to confirm and extend these findings.
Tumors and Cancer Treatment
L-theanine has also been linked to enhancing the anti-tumor effects of certain chemotherapy drugs. Because of these promising findings, researchers anticipate that L-theanine may also help improve the cancer-fighting power of chemotherapy.
Although there is no conclusive evidence that tea can prevent cancer, many studies show that people who drink tea regularly have a lower chance of developing cancer.
A Chinese study found that women diagnosed with ovarian cancer who drank at least one cup of green tea a day lived longer than those who did not drink green tea.
Another study comparing tea drinkers with non-tea drinkers found that women who drank green tea were 32% less likely to develop pancreatic cancer.
blood pressure management
L-theanine may be beneficial for those whose blood pressure increases during stressful situations.
One study found that people whose blood pressure typically rises after performing certain mental tasks found that L-theanine helped reduce the rise in blood pressure.
In the same study, researchers noted that caffeine had similar but less beneficial effects.
Some research suggests that L-theanine may be beneficial for good sleep, possibly because it helps promote relaxation.
Researchers found in one study that doses of 250 mg and 400 mg of L-theanine significantly improved sleep in animals and humans.
Additionally, 200 mg of L-theanine has been shown to help lower resting heart rate, suggesting its ability to promote relaxation.
L-theanine may also help boys diagnosed with attention deficit hyperactivity disorder (ADHD) sleep better.
A double-blind study examined the effects of L-theanine on 98 boys aged 8 to 12 years. Patients were randomized to take two 100 mg L-theanine chewable tablets twice daily. The other group received placebo pills.
After six weeks, the group taking L-theanine slept longer and more restfully. While the results are encouraging, more research is needed before it can be proven safe and effective, especially in children.
Other studies have shown that L-theanine can improve sleep quality in people with schizophrenia.
L-Theanine Risks and Side Effects
There are no proven or direct side effects from consuming L-theanine. Generally speaking, drinking tea and taking supplements containing L-theanine are safe.
But it’s worth noting that the U.S. Food and Drug Administration (FDA) does not regulate supplements. The manufacturers of these products are responsible for ensuring the safety of their products.
However, while some studies have shown beneficial effects of L-theanine's anti-tumor properties, tea containing the amino acid may contain other ingredients that may be harmful to people undergoing cancer treatment.
According to Memorial Sloan Kettering Cancer Center, the polyphenol EGCG found in green tea can reduce the effectiveness of certain chemotherapy drugs, such as bortezomib.
Therefore, it is important for people taking chemotherapy drugs to talk to their healthcare provider before drinking green tea as part of their treatment plan.
Although there have been no reports of side effects from taking L-theanine, due to the caffeine in it, drinking large amounts of green tea may cause:
- nausea
- upset stomach
- irritability
Women who are pregnant or breastfeeding should also limit the amount of tea they drink to avoid consuming too much caffeine.
It's best to ask your healthcare provider what's safe for you. The same advice applies to children.
Safe Dosage Recommendations for L-Theanine
Safe L-theanine dosage recommendations are unclear as there are no conclusive studies. But if you drink tea, it may be helpful to follow general caffeine intake guidelines.
For people taking L-theanine supplements, it is best to consult a healthcare provider for dosage guidance.
