L-theanine is an amino acid that is found primarily in dietary sources like green tea and matcha. Most often studied for its effects on reducing stress and promoting calmness, L-theanine also supports sleep, immune function, and blood pressure control.
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In this article, we will discuss what L-theanine is, where it’s found, and the top five health-promoting benefits that it has.
L-theanine is a unique amino acid commonly found in green tea leaves but is also in smaller amounts in black tea, white tea, and some mushrooms.
It’s unique in that it doesn’t function as a building block to proteins, as most other amino acids do. It’s not commonly found in foods and is not required by our bodies. Therefore, L-theanine is considered a non-dietary, nonessential amino acid.
Even though it is deemed nonessential, there are several health-promoting properties associated with L-theanine. The primary benefit of L-theanine is that it stimulates a calm and focused state of mind, relieves stress and promotes calmness, and leads to better sleep.
The calming effects of L-theanine stem from its ability to produce the neurotransmitters GABA and dopamine, which have relaxation-promoting qualities. At the same time, L-theanine also reduces levels of glutamate, an excitatory neurotransmitter. It does this by binding to glutamate receptors and increasing GABA, which competes with glutamate’s re-uptake in the brain.
Structurally, L-theanine is very similar to the amino acid glutamine, which produces glutamate. Through L-theanine, the upregulation of GABA can counterbalance glutamate levels.
Although some glutamate is still needed for a healthy brain, excess amounts can increase stress and agitation. GABA and glutamate have sometimes been referred to as the yin and yang of neurotransmitters, as the combination of the sedative-like properties of GABA and the excitatory nature of glutamate creates a perfect amount of stimulation when in balance.
This yin-yang balance makes L-theanine a natural anxiolytic, a medication or therapeutic intervention that reduces symptoms of unease or agitation. However, unlike prescription anxiolytics, L-theanine can bring on the calm without creating drowsiness.
Research has also backed up the anxiolytic properties of L-theanine. An October study published in Nutrients randomized 30 adults to receive either 200 mg per day of supplemental L-theanine or a placebo. Those in the L-theanine group had significantly reduced levels of low mood, stress, and agitation after four weeks.
Another study published in Nutrients found that adults who consumed a beverage containing 200 mg of L-theanine had reductions in their response to a cognitive stress test one hour after drinking it and reductions in salivary cortisol levels three hours later.
In the October study in Nutrients, adults who took 200 mg of L-theanine before bed also had significant reductions in sleep latency (the time it takes to fall asleep), sleep disturbances, and usage of sleeping medication throughout the four-week study.
The mechanisms behind how L-theanine benefits sleep are similar to that of its calming properties. Through GABA upregulation, L-theanine promotes a relaxing and calm state to wind down for bed.
Another related benefit of L-theanine is how it promotes a state of wakeful relaxation — the kind of peaceful brain state that you experience during meditation, creative work, or anything that puts you in a flow state.
L-theanine produces focused energy through its enhancement of alpha brain waves, which are associated with calmness, relaxation, and contentment, but without drowsiness or fatigue. Consumption of L-theanine in combination with caffeine — like green tea and matcha — amplifies the effects on cognition and focus. In a December trial published in Nutritional Neuroscience, a combination of 97 mg of L-theanine with 40 mg of caffeine led to significant improvements in accuracy during task switching and self-reported alertness and tiredness.
Lastly, L-theanine benefits cognition through its ability to increase brain-derived neurotrophic factor (BDNF), a protein that is essential for maintaining and growing new neurons. BDNF is known to be neuroprotective.
L-theanine has been shown to modulate blood pressure through two mechanisms. First, stress can elevate blood pressure by increasing levels of vasoconstricting hormones, and L-theanine is known to reduce stress.
Secondly, L-theanine can stimulate nitric oxide production, which is a vasodilator that reduces blood pressure.
A study published in the Journal of Physiological Anthropology found that 200 mg of supplemental L-theanine was able to attenuate blood pressure elevation that was induced by stressful mental tasks. The greatest improvement was seen in people considered “high responders” because they typically have elevated blood pressure in stressful situations.
While these results are promising for acute blood pressure control, no studies have been done assessing L-theanine’s effects on longer-term blood pressure regulation.
Lastly, L-theanine may support immune system functioning through its ability to upregulate certain immune cells and decrease pro-inflammatory compounds. L-theanine has been shown to enhance the innate immune system, our body’s first line of defense against pathogens, through regulation of cytokines.
A common combination used in studies on immune function is L-theanine with L-cysteine, another amino acid. Research has shown that this combination is linked to improved immune function in endurance athletes as well and the elderly population.
Although more research still needs to be done on the effects of L-theanine on immunity, the results so far are encouraging.
Although you can get L-theanine from green tea and matcha, more benefits are seen with higher amounts found in supplements. Matcha, a powder made up of green tea leaves, has higher L-theanine than green tea, which is just the water that the tea leaves were steeped in.
One cup of tea contains approximately 25 mg of L-theanine, whereas supplements range from 50 to 200 mg. In the studies mentioned in this article, 200 mg of L-theanine per day was the most common dosage.
Whether you’re drinking tea or taking a supplement, L-theanine has been shown to cross over the blood-brain barrier and take effect within 30 to 120 minutes of ingesting it.
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There are no major side effects reported with L-theanine usage. However, people taking blood pressure medications may want to be careful due to the potential blood pressure-lowering effects of L-theanine.
If you are pregnant, breastfeeding, or tend to have low blood pressure, ask your doctor before consuming L-theanine in supplemental form.
References:
Giesbrecht T, Rycroft JA, Rowson MJ, De Bruin EA. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. ;13(6):283‐290. doi:10./X
Hidese S, Ogawa S, Ota M, et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients. ;11(10):. Published Oct 3. doi:10./nu
Juszkiewicz A, Glapa A, Basta P, et al. The effect of L-theanine supplementation on the immune system of athletes exposed to strenuous physical exercise. J Int Soc Sports Nutr. ;16(1):7. Published Feb 15. doi:10./s-019--y
Li C, Tong H, Yan Q, et al. L-Theanine Improves Immunity by Altering TH2/TH1 Cytokine Balance, Brain Neurotransmitters, and Expression of Phospholipase C in Rat Hearts. Med Sci Monit. ;22:662‐669. Published Feb 28. doi:10./msm.
Lorenz M, Urban J, Engelhardt U, Baumann G, Stangl K, Stangl V. Green and black tea are equally potent stimuli of NO production and vasodilation: new insights into tea ingredients involved. Basic Res Cardiol. ;104(1):100‐110. doi:10./s-008--3
Lyon MR, Kapoor MP, Juneja LR. The effects of L-theanine (Suntheanine®) on objective sleep quality in boys: a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev. ;16(4):348‐354.
Nobre AC, Rao A, Owen GN. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. ;17 Suppl 1:167‐168.
Ota M, Wakabayashi C, Sato N, et al. Effect of L-theanine on glutamatergic function in patients. Acta Neuropsychiatr. ;27(5):291‐296. doi:10./neu..22
Rothenberg DO, Zhang L. Mechanisms of Regular Tea Consumption. Nutrients. ;11(6):. Published Jun 17. doi:10./nu
White DJ, de Klerk S, Woods W, Gondalia S, Noonan C, Scholey AB. Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial. Nutrients. ;8(1):53. Published Jan 19. doi:10./nu
Williams J, Kellett J, Roach P, et al. l-Theanine as a Functional Food Additive: Its Role in Disease Prevention and Health Promotion. Beverages. ;2(2):13. doi:10./beverages
The magic of L-theanine lies in its ability to increase activity of alpha brain waves, which induce a feeling of calm relaxation, without causing drowsiness.1 A study investigating the effect of 250 mg of L-theanine on alpha brain waves in subjects found that L-theanine had a significant effect on the general state of mental alertness, and plays a more general role in “…facilitating longer-lasting processes responsible for sustaining attention across the timeframe of a difficult task...”2
Another study explored the combined effects of 250 mg of L-theanine plus 150 mg of caffeine with similar findings. Visual information processing and mental fatigue ratings improved; faster reaction times, numeric working memory reaction times, and improvements in word recognition reaction times were all reported in the L-theanine and caffeine group.3 A separate study examining the ability of participants to maintain focus on monotonous tasks over a two-hour period, showed that those taking a combination of 100 mg of L-theanine plus 50 mg of caffeine had a significant reduction in errors compared to an increase in errors in the placebo group.4
Even without the addition of caffeine, L-theanine delivers. A 12-week randomized, placebo-controlled study looking at the effects of 100 mg of L-theanine on cognitive function showed positive results after one dose. After just a single dose of L-theanine, subjects saw an improvement in attention tasks, an increase in the number of correct answers, and a decrease in the number of errors in working memory tasks. The researchers concluded, “Our study indicated that L-theanine may contribute to improving attention, thus enhancing working memory and executive functions.”5
L-theanine also supports attention, learning, and reaction times in those with high anxiety. One study on L-theanine in college-aged subjects backs this up. Eighteen subjects were classified as either having high anxiety or minimal/low anxiety and were separated into those respective groups. Both groups were given 200 mg of L-theanine and a placebo over the duration of the study. Fifteen to 60 minutes after taking L-theanine or placebo, they underwent assessments on visual and audio attention and response tests. The results on anxiety markers showed “a significant enhanced activity of alpha [waves], descending heart rate, elevated visual attentional performance, and improved reaction time response among high-anxiety propensity subjects compared to a placebo.” The study concluded, “Results evidently demonstrated that L-theanine clearly has a pronounced effect on attention performance and reaction time response in normal healthy subjects prone to have high anxiety.”6 They noted that no significant differences were evident among subjects with minimal anxiety.
Another randomized, placebo-controlled study looked at the effects of taking 200 mg of L-theanine daily for four weeks on stress-related symptoms, sleep, and cognitive function. The 30 participants were healthy adults 48 years and older. The Self-Rating Depression Scale, State-Trait Anxiety Inventory-Trait, and Pittsburg Sleep Quality Index (PSQI) scores all improved after taking L-theanine. Furthermore, scores for sleep latency (amount of time it takes to fall asleep), sleep disturbance, and use of sleep medication all were reduced in the L-theanine group, compared to the placebo group.7
The same study found that when it came to cognitive function, verbal fluency, and executive function, scores improved after L-theanine administration, especially letter fluency (naming as many words as possible that start with a specific letter in a specified amount of time) when compared to those taking a placebo. They summarized, “Our findings suggest that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments.” Other research has found theanine reduces stress-induced rises in blood pressure, another way it supports the whole body under stress.8
When there’s a chemical imbalance in the brain, there’s no one-size-fits-all answer. Maintaining your mental health means taking a multifaceted approach—implementing things like talk therapy, regular self-care, nutrition, exercise, vitamins, and supplements daily. L-theanine is one of those supplements that shows promise in helping combat depression at the source.
In one study, L-theanine was examined for its effectiveness in patients with major depressive disorder (MDD). Findings revealed that after eight weeks of 250 mg/day of L-theanine depression and anxiety scores decreased and sleep scores improved. Cognition, verbal memory, and executive function were also enhanced, and error rate decreased. They concluded, “…L-theanine administration is safe and has multiple beneficial effects on depressive symptoms, anxiety, sleep disturbance, and cognitive impairments in patients with MDD.”9
Another study investigating the effects of L-theanine on an animal model of depression showed that rats with chronic mild stress and depression symptoms experienced a significant increase in neurotransmitters such as serotonin, norepinephrine, and dopamine after administration of L-theanine. The researchers summarized that L-theanine possibly had antidepressant-like effects.10
Beyond calm and focus, L-theanine appears to have a protective effect on brain function. In studies of older adults with mild to moderate cognitive decline, L-theanine supplementation improves attention and memory both acutely and after long term use.11 12 Getting at least some theanine from green tea may offer additional benefits, since green tea is rich in polyphenols that may modulate inflammation and protect against oxidative damage in the brain as we age.11 13 14
Don’t let a scattered, stressed-out, sleep-deprived day get in the way of your true potential. Reach for L-theanine for the cool calm!
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