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Everything You Need to Know About L-Theanine

L-theanine is a amino acid found in only a handful of foods. If you've already taken steps to create a nighttime routine and reduce stress, yet you still struggle with insomnia and anxiety that interferes with your sleep, this may be a supplement worth adding to your repertoire*. Let's take a deeper look at this unusual amino acid and its effects on sleep quality and cognitive function so you can figure out if its right for you.

What is L-Theanine?

l-theanine in green tea
First discovered in 1949 by Japanese scientists, theanine (1) is an amino acid that you'll typically find in all types of tea leaves (except herbal varieties):
  • green tea or green tea extract
  • black tea
  • oolong tea
It can also be found in trace amounts in some mushrooms. If you feel calm, relaxed and alert after an afternoon cup of tea, it may just be because of l-theanine. We'll explain deeper later, but caffeine and theanine have may have a synergistic effect on the brain. L-Theanine is an interesting amino acid because it is able to cross the blood brain barrier. To top it off, experts believe l-theanine is a natural source of umami -- a savory flavor enhancer. You can find this amino acid in supplement, powder, and liquid forms.

What are the potential Benefits of L-Theanine?

l-theanine in oolong tea
Although l-theanine isn't an essential amino acid, that doesn't mean it can't improve your health. Let's have a look at the most well-documented health benefits.

L-Theanine May Improve Sleep Quality

Theanine appears to improve objective sleep quality even in folks with various mental health disorders. (2, 3) Studies show that theanine doses of 200 to 400 mg may reduce your resting heart rate and encourage healthy relaxation, so it's easier to fall asleep.

May Reduce Anxiety Symptoms

L-theanine is commonly used for relaxation. Double blind studies have shown that l-theanine may be useful in reducing symptoms of anxiety for people during stressful situations. (4)
Interestingly, l-theanine is able to help with relaxation without causing drowsiness. (5)

May Improve Cognitive Function

Studies show that l-theanine can boost alpha brain waves -- especially in folks prone to anxiety -- which promote hand-eye coordination, learning, calmness, and focus. (6) Although it's an amino acid, l-theanine almost functions as an adaptogen in terms of reducing psychological stresses and improving your stress response. When you're in a stressful situation, your body produces hormones like cortisol and corticosterone. These hormones interfere with your ability to focus and make proper decisions. When you take l-theanine, it can reduce your stress hormone levels so you can focus better. (7) Finally, l-theanine offers added nootropic benefits when you combine it with caffeine.

What You Should Know About Combining L-Theanine and Caffeine

beverages l-theanine and caffeine
L-Theanine and caffeine create a nootropic powerhouse. We've all been there: You're feeling tired from a poor night's sleep, so you pound caffeine through the morning. The next thing you know, you're a ball of anxiety, jittery, and you don't even feel focused or awake! L-Theanine is great because it can help balance the effects of caffeine intake. Since l-theanine impacts your GABA levels and crosses the blood-brain barrier, it can help you enjoy the alert feelings of caffeine without feeling anxious or stressed. Remember when we mentioned that green tea makes you feel alert and energized yet calm and relaxed? The unique green tea components of l-theanine and caffeine are exactly why.

Side Effects and dosage

In general, l-theanine is considered safe with no direct side effects. Most people take 100 to 200 mg of theanine in capsules or mix it in powder form into their coffee to balance the effects of caffeine. If you take capsules, it's a good idea to take your morning l-theanine about 30 minutes before you start sipping your coffee. You can take this combination of l-theanine on an empty stomach without any food to aid absorption. Although there aren't any known side effects of l-theanine, you should still talk to a doctor before taking it as a dietary supplement if you are taking other medication or have a medical condition.

The Bottom Line

L-Theanine is a somewhat rare amino acid mainly found in tea leaves like green tea and black tea, as well as some mushrooms. Since it's extremely safe with no known adverse effects, easy to find, and essentially flavorless, it's easy to experiment with theanine as a dietary supplement. Take a few capsules before your morning cup of coffee and see how it works to boost cognitive performance and reduce anxiety with your caffeine intake!
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