Here you will find out just what theanine in your brew can do – you won’t think of tea in the same way again.
Discovered by Japanese scientists in 1949, theanine is an amino acid that is most commonly found in tea leaves. It's also known as l-theanine.
Theanine is available as a supplement, with a recommended dosage of 200mg per day.
Other evidence suggests, that when consumed in tea, theanine may change taste perception. Specifically, by lowering the bitter taste in foods such as chocolate and grapefruit.2
A nice cuppa is known to help you relax. But there are many other potential health benefits that you might not know about theanine.
Here you will find four ways that theanine can improve brain function and imrpove sleep.
It’s unlikely that the consumption l theanine will make you happy. However, when you take the above factors into consideration, it may be that you see improvements in your overall wellbeing. After all – feeling relaxed, getting enough sleep and a healthy diet will definitely help.
Now you know what theanine does, its probably best you know how it works.
We know that it stimulates relaxation, which helps contribute to better sleep, but how does l theanine contribute to making those changes in the brain?
L-theanine works by raising Gamma Aminobutyric Acid (GABA)5 as well as serotonin and dopamine in the brain. These are chemicals in the brain, known as neurotransmitters, that help you control your cognitive skills.
By Increasing levels of these calming brain chemicals, you can help promote relaxation and improve your sleep.
Neurotransmitters help regulate your:
This doesn’t mean that you are less likely to feel excitement, but l theanine may reduce and help anxiety by balancing the chemicals in your brain that are linked to stress. It is thought that this may also be a way that l theanine can help protect ageing brain cells.
L-theanine releases alpha brain waves. Alpha brain waves are the state of mind you reach when meditating, being creative or letting your mind go when daydreaming. They also occur when you reach a state of REM when sleeping.
This can make l-theanine an attractive choice for people who are looking to enhance their “wakeful relaxation,” without worrying about becoming fatigued.
As mentioned above, l theanine is a unique compound found in tea that has many relaxing qualities that helps aid concentration and sleep.
Tea is the main source that we consume l-theanine as it doesn’t particularly occur naturally in many other foods.
As we all know, making a cup of tea is common practice. Although it probably goes without saying that how you prefer your tea is entirely down to your own taste and always a good debate! This can also determine the amount of l theanine you are getting in your cuppa.
Brewing time and amounts of milk can determine how l-theanine we receive.6 For a standard cup of tea (200ml) you are likely to consume:
L-theanine is also found in the boletus badius mushroom, although it's not clear exactly how much or how many you would need to use to make it beneficial without more detailed research.
Generally, there are no side effects to l theanine and its safe for healthy adults to take supplements and drink teas that contain l theanine.
Most l theanine supplements contain around 200mg, but there is no conclusive research that says just how much you should have. Drinking tea is generally safe for most people, and there have been no reports of overdose or side of affects of l theanine.
However, it’s worth keeping in mind that many l theanine supplements may contain caffeine, so its worth following the same guidelines as caffeine (400 mg)7.
Like caffeine, it is thought that if you consume excessive amounts of l theanine you may experience:
It would be considered best practice to consider your l theanine intake and consult your doctor if you are:
There is some evidence to suggest that l theanine can benefit your mental and physical health. However, more scientific research is needed before it can be proven just what effects the amino acid l theanine has.
Last updated: 27 April 2021
Joined Holland & Barrett: Apr 2019
Masters Degree in Toxicology and BSc Hons in Medical Biochemistry
Bhupesh started his career as a Clinical Toxicologist for Public Health England, advising healthcare professionals all around the country on how to manage clinical cases of adverse exposure to supplements, pharmaceuticals, cosmetics, industrial chemicals and agricultural products.
After 7 years in this role and a further year working as a drug safety officer in the pharmaceutical industry, Bhupesh joined Holland & Barrett as a Senior Regulatory Affairs Associate in 2019.