What about L-Theanine

What about L-Theanine

L-Theanine is touted as a calming substance for parrots. Like a lot of things you read on the internet, no evidence is given to support any claims. So, let’s change that.

The products

First off, there are a number of products that contain L-Theanine, including one called UnruffledRx Parrot Calming Formula. It’s important to have a long name!

No, it’s not a roll-on.

The claim they make is:

UnRuffledRx Parrot Calming Formula,with the active ingredient, L-Theanine, a Green Tea derivative, enhances alpha waves in the brain to produce a calming, yet non-sedating effect. L-Theanine has been found to improve alertness and disposition.

So, let’s take a look at these.

Theanine is found primarily in plant and fungal species. It was discovered as a constituent of tea (Camellia sinensis) in 1949 and in 1950, a laboratory in Kyoto successfully isolated it from gyokuro leaf, which has high theanine content. Theanine is substantially present in black, green, and white teas from Camellia sinensis in quantities of about 1% of the dry weight.



Large studies in humans have not been undertaken; however, several smaller-scale studies (fewer than 100 participants) have shown increased alpha wave generation and lowered anxiety, along with benefits to sleep quality in people with ADHD.


CONFIRMED. A reasonable claim. A study of 100 is a decent size to draw conclusions from.

For alertness there are two conflicting studies, and both involve also using caffeine.

“L-Theanine and caffeine improve task switching but not intersensory attention or subjective alertness”

“The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness”



Let’s look at L-Theanine itself and the research. There are some quite small studies but also some very impressive ones. This first one is a study of 20 dogs.

L-Theanine inhibits the reuptake of glutamate and increases GABA levels, generating an anti-stress effect and a sense of well-being, and has neuroprotective effects in the hippocampus by blocking the multiple receptor subtypes of glutamate.

Effectiveness of L-theanine and behavioral therapy in the treatment of noise phobias in dogs—Journal of Veterinary Behavior—Jan/Feb 2010

A study of thirty-four human subjects. A double-blind, placebo-controlled trial.

The findings of the present study further support the anti-stress effects of l-theanine. Following administration of the active treatment, a nutrient beverage containing 200 mg of l-theanine, in addition to smaller doses of PS, alpha GPC and chamomile, subjective stress response to a cognitive stressor was found to be significantly reduced one hour post-dose, and cortisol response was significantly reduced three hours post-dose, using a double-blind, placebo-controlled, balanced crossover design. No differences in cognitive performance were observed. 

Anti-Stress, Behavioural and Magnetoencephalography Effects of an l-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial—Nutrients—Jan 2016

A small double-blind study of 12 human subjects.

The results showed that L-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

L-Theanine reduces psychological and physiological stress responses—Biological Psychology—Jan 2007

A small study on 8 human subjects suffering from varying degrees of anxiety.

Four of them were ranked to be Grade I (the highest anxiety) and the remaining four, Grade V (the lowest anxiety) in an investigation done by the manifest anxiety scale method.

he emission intensity of α-brain waves (integrated as a function of investigation times and area) was significantly greater in the group of Grade I than that of Grade V. These results indicate the possibility for L-theanine to be applied to foods and beverages as a new type of functional food ingredient for its relaxation effect.

Effects of L-Theanine on the Release of α-Brain Waves in Human Volunteers—Nippon Nōgeikagaku Kaishi—1998, Issue 2

A study of 30 cats.

Although this study does not contain any control group, it suggests that in stressed cats, administration of L-theanine (Anxitane®) twice daily may help improve undesirable signs in as soon as 15 days, though better results were seen after 30 days of administration. These encouraging results showed that L-theanine can help manage stress related behaviour, although additional trials with a placebo group should be run to confirm this effect.

Effect of l-theanine tablets in reducing stress-related emotional signs in cats: an open-label field study—Irish Veterinary Journal—2018

A study of 98 boys with Attention deficit hyperactivity disorder.

This study demonstrates that 400 mg daily of L-theanine is safe and effective in improving some aspects of sleep quality in boys diagnosed with ADHD. Since sleep problems are a common co-morbidity associated with ADHD, and because disturbed sleep may be linked etiologically to this disorder, L-theanine may represent a safe and important adjunctive therapy in childhood ADHD. 

The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial—Alternative Medical Review—Dec 2011

And a meta-study including 104 participants.

The findings in four studies indicated significant improvements in reducing stress and anxiety.

Theanine consumption, stress and anxiety in human clinical trials: A systematic review—Joint Annual Scientific Meeting of the Nutrition Society of New Zealand and the Nutrition Society of Australia—December 2015

And if that’s not enough, Taylor Swift Says She Takes L-Theanine For Her Anxiety.

Taken together, it seeems reasonable to conclude that L-Theanine has calming properties and there is no particular concern with dosage. There is also significant anecdotal evidence for both humans (either with tea or supplements) or with people’s birds that it does indeed have a calming effect.