See if this sounds familiar…

You should have been out the door ten minutes ago but you can’t find your car keys. You’re feeling anxious because you know traffic is bad and now you’re going to be late. To make matters worse, you didn’t sleep well the night before and now you’re tired, which is adding to your stress.

The more stressed and anxious you feel, the harder it is to think. And because you can’t think straight, you can’t remember where you left the keys.

It’s a vicious circle that we’ve all experienced. The question is, can you break out of it? Yes, you can.

L-theanine can help to solve all these problems. It mitigates stress and anxiety, improves your ability to focus and think straight, and enhances your sleep.

I’ve used car keys in this example, but it could be anything that you need to remember. Or any situation that calm and clear thinking will help. Let’s go further.

What Is L-theanine?

L-theanine is a natural component of green and black tea that is available in a concentrated form in dietary supplements. It has a calming effect without making you feel drowsy. And it helps you to focus attention and be mentally sharper, even though it is not a stimulant.

If you take L-theanine during the day, it helps you to be more mentally alert and to concentrate better while feeling less stressed and less anxious. If you take it before bedtime, the calming effect helps you get a better night’s sleep.

How L-theanine Works

To see how L-theanine works, researchers measured brain activity in people who took either L-theanine or a placebo. They found that unlike the placebo, L-theanine increased alpha brain waves.[1]

Alpha waves promote relaxation in the brain and nervous system without making you drowsy. They also make it less likely that you’ll get distracted, which makes it easier to stay focused on the task at hand.

Animal studies suggest that L-theanine can also improve learning and memory and helps to protect the brain and nervous system against damage.[2]

5 Important Health Benefits of L-theanine

Here are five ways that L-theanine supplements can enhance your health, and an additional benefit for pets.

1. Improving Focus and Attention

Do you ever feel scatter-brained? You might think it’s a side effect of aging, but it doesn’t have to be. Studies have shown that L-theanine can improve focus, attention, and overall mental function in people of all ages.

One study tested L-theanine on people who were between the ages of 50 and 69. They were healthy but had experienced some decline in mental function as they got older.

Their mental performance was tested a week before taking the supplement, to get a baseline score for comparison, and then a week later. The second round of testing was done about 50 minutes after the subjects took 100 mg of L-theanine.

Subjects taking L-theanine showed significant improvement -- reaction time was shorter and their attention, focus, working memory, and overall mental function improved.[3]

Another study tested 200 mg of L-theanine on healthy college students suffering from varying degrees of anxiety. Mental tests, done between 15 and 60 minutes after taking the supplement, showed that L-theanine was especially beneficial for those who experienced anxiety. It lowered heart rate, shortened reaction time, and improved attention and mental performance.[4]

The supplements used in both of these studies contained Suntheanine®, a patented form of L-theanine that is the most widely studied. Suntheanine is an ingredient in many dietary supplements.

2. Enhancing Sleep

Getting enough sleep is beneficial in many ways, from reducing risk for major diseases such as diabetes and heart disease to improving our sense of well-being, mood, and ability to think clearly. Adequate sleep even makes it less likely that you’ll overeat and gain weight. But today’s stressful world can make it difficult to get enough restful sleep.

Sleeping pills can cause dangerous drowsiness the next day. Other unpleasant side effects may include constipation or diarrhea, headache, heartburn, unusual dreams, memory problems, and others. What’s more, sleeping pills can be addictive.

L-theanine is not addictive and it enhances sleep without adverse effects or drowsiness the next day. Studies show that, unlike drugs, L-theanine is not a sedative. Instead, it works by promoting alpha brain waves that calm naturally. It’s gentle but effective.[5]

To enhance sleep, 200 mg of L-theanine is a common dose, taken before bedtime.

3. Reducing Stress

Stress isn’t always bad. It can be a healthy response that motivates us to overcome challenges. In ancient times, when a dangerous animal approached, the fight-or-flight stress response helped our ancestors to run for their lives by providing a burst of adrenaline and increased energy. They escaped often enough for humanity to carry on — after all, we’re here.

Today, we aren’t running from wild animals. But traffic jams, difficulties at work, and emotional upsets can trigger our stress responses often, or even keep them going continuously. And this overstimulation can lead to many ills, from stomach upsets and headaches to irritability, depression, high blood pressure, and even faster aging.

Studies have proven that L-theanine reduces stress. People who took L-theanine have routinely reported feeling less stressed, but that’s not all. Objective tests by researchers have shown that L-theanine reduces elevated heart rate and other physical markers of stress.[6]

One study looked at fifth-year pharmacy students beginning a particularly stressful part of their training program. And it compared the effects of L-theanine with a placebo.

Those in the study took either 200 mg of L-theanine or the placebo twice a day, after breakfast and lunch. They started taking the supplements one week before the especially stressful part of their program began, and for the next ten days.

At the end of the study period, those taking a placebo felt quite stressed, as expected. But those who took L-theanine reported feeling significantly less stressed. And saliva tests documented that L-theanine lowered physical markers of stress.[7]

4. Lowering Blood Pressure

Stress is often a driver of chronic elevated blood pressure that raises risk for heart disease, stroke, kidney and eye problems, and memory troubles. By reducing stress, L-theanine can help.

In addition, some people have what researchers call a “high stress response” to challenging mental tasks, where their blood pressure suddenly rises by more than an average amount. Such temporary spikes in blood pressure can damage blood vessels.

L-theanine can tame harmful blood pressure surges in the face of mental challenges. One study found that taking 200 mg of L-theanine significantly reduced blood-pressure spikes during a stressful arithmetic test.[8] The supplement in this study contained the patented Suntheanine form of L-theanine.

Even in healthy people whose blood pressure is generally normal, stress-induced spikes can lead to chronic high blood pressure down the road. L-theanine can help to prevent this from happening.

5. Reducing Anxiety

Who hasn’t occasionally felt anxious? Whether this happens only once in a while or anxiety is an ongoing concern, L-theanine can help.

A review of 9 peer-reviewed studies found that taking between 200 and 400 mg of L-theanine daily can reduce anxiety. Stress, which often triggers anxiety, was also relieved.[9]

Other research found that L-theanine is beneficial for both acute and ongoing anxiety. And doses lower than 200 mg, or higher than 400 mg, can also be therapeutic.[10]

Calming Dogs and Cats

Humans aren’t the only ones who can benefit from L-theanine. Studies have found that stressed, anxious, or fearful dogs and cats can be calmed by the supplement.

One study tested L-theanine on dogs who were sensitive to storms. The supplements reduced dogs’ drooling, pacing, panting, following people, and hiding, and dogs returned to their normal selves sooner after a storm.[11] Another study found that L-theanine reduced dogs’ fear of unfamiliar humans.[12]

L-theanine was also tested on cats that had been stressed for at least a month, with symptoms such as fear, aggression, tension, or unusual urination or defecation. L-theanine improved symptoms in 91 percent of stressed cats.[13]

These studies of dogs and cats used a supplement specially formulated for pets, which contained the patented Suntheanine form of L-theanine.

Can You Get L-theanine from Food?

Green and black teas are the sources of L-theanine in our diets. However, there’s no way to tell exactly how much L-theanine is in a cup of tea and it isn’t realistic to get therapeutic amounts simply by drinking tea.

When researchers tested L-theanine content of teas, they found that it varied quite a bit. One study measured L-theanine in a 7-ounce cup and found that green tea contained between 4 and 12 mg and black tea contained between 18 and 30 grams.[14]

Generally, brewing tea for a longer time increased L-theanine content. However, adding milk decreased L-theanine.

Green and black teas both come from the same plant: Camellia sinensis. Herbal teas come from other plants and do not contain L-theanine.

How Much L-theanine Should I Take?

Although there is no standard recommended dose, studies have generally used between 100 mg and 400 mg of L-theanine daily. When the supplement is taken by itself, 200 mg is a common dose. For older people looking to improve mental function, 100 mg daily produced a noticeable benefit.

L-theanine can start to work in about 30 minutes after taking the supplement, and effects last 5 hours or more.[15] For better concentration and/or less stress or anxiety during the day, take it with breakfast or lunch. For better sleep, take it before bedtime.

Formulations of L-theanine can differ. Suntheanine is a patented form of L-theanine that has been most widely studied and is found in many supplements. On product labels, the Supplement Facts will show if a product contains the Suntheanine form.

For cats and dogs, look for a supplement specially formulated for them and follow product recommendations for your pet’s size. In studies, L-theanine was given to dogs and cats twice daily. Benefits were seen in cats after 15 days, and more so after 30 days. Dogs took one to two months to show full benefits.

Does L-theanine Have Side Effects or Risks?

There have not been any reports of adverse effects from L-theanine supplements. Some studies have tested daily doses of more than 400 mg and found them to be safe and well tolerated.

The Bottom Line

Green and black tea contains L-theanine but not enough to deliver the benefits seen in studies of L-theanine supplements. If your aim is to enhance your attention and focus, reduce stress or anxiety, sleep better, or reduce blood pressure, take L-theanine supplements. And if you like to drink tea, go ahead and enjoy it!

References

  1. Nobre, A.C., et al. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. 2008;17 Suppl 1:167-8.
  2. Nathan, P.J., et al. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30.
  3. Baba, Y., et al. Effects of L-theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study. J Med Food. April 2021; 24(4): 333–341.
  4. Higashiyama, A., et al. Effects of L-theanine on attention and reaction time response. Journal of Functional Foods 2011 Jul;3(3):171-178.
  5. Rao, T.P., et al. In Search of a Safe Natural Sleep Aid. J Am Coll Nutr. 2015;34(5):436-47.
  6. Kimura, K., et al. L-theanine reduces psychological and physiological stress responses. Biological Psychology. 2007 Feb;74(1):39-45.
  7. Unno, K., et al. Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary α-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav. 2013 Oct;111:128-35.
  8. Yoto, A., et al. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012; 31(1): 28.
  9. Williams, J.L., et al. The Effects of Green Tea Amino Acid L-theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. Plant Foods Hum Nutr. 2020 Mar;75(1):12-23.
  10. Sakamoto, F.L., et al. Psychotropic effects of L-theanine and its clinical properties: From the management of anxiety and stress to a potential use in schizophrenia. Pharmacol Res. 2019 Sep;147:104395.
  11. Pike, A.L., et al. An open-label prospective study of the use of L-theanine (Anxitane) in storm-sensitive client-owned dogs. Journal of Veterinary Behavior. 2015 Jul-Aug;10(4):324-331.
  12. Araujo, J.A., et al. ANXITANE® tablets reduce fear of human beings in a laboratory model of anxiety-related behavior. Journal of Veterinary Behavior. 2010 Sep-Oct;5(5):268-275.
  13. Dramard, V., et al. Effect of L-theanine tablets in reducing stress-related emotional signs in cats: an open-label field study. Ir Vet J. 2018; 71: 21.
  14. Keenan, E., et al. How much theanine in a cup of tea? Effects of tea type and method of preparation. Food Chemistry. 2016 Mar;125(2):588-594.
  15. Adhikary, R., et al. L-theanine: A potential multifaceted natural bioactive amide as health supplement. Asian Pacific Journal of Tropical Biomedicine. 2017 Sep;7(9):842-848.