L-Theanine: What’s The Tea?

We’ve touched previously on l-theanine, when this newsletter was new, and we had only a few hundred subscribers and the carefully organized format wasn’t yet what it is today.

So now it’s time to give this potent dietary compound / nutritional supplement the “Monday Research Review” treatment…

What is it?

L-theanine is an amino acid found in tea. The human body can’t produce it, and/but it’s not essential for humans. It does have a lot of benefits, though. See for example:

L-Theanine as a Functional Food Additive: Its Role in Disease Prevention and Health Promotion

How does it work?

L-theanine works by moderating and modulating the brain’s neurotransmitters.

This sounds fancy, but basically it means: it doesn’t actually add anything in the manner of a drug, but it changes how we use what we have naturally.

What does it do? Read on…

It increases mental focus

It has been believed that l-theanine requires the presence of caffeine to achieve this (i.e., it’s a combination-only effect). For example:

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

But as it turns out, when a group of researchers actually checked… This isn’t true, as Foxe et al. write:

❝We asked whether either compound alone, or both in combination, would affect performance of the task in terms of reduced error rates over time, and whether changes in alpha-band activity would show a relationship to such changes in performance. When treated with placebo, participants showed a rise in error rates, a pattern that is commonly observed with increasing time-on-task, whereas after caffeine and theanine ingestion, error rates were significantly reduced. The combined treatment did not confer any additional benefits over either compound alone, suggesting that the individual compounds may confer maximal benefits at the dosages employed❞

See: Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task

It promotes a calmly wakeful feeling of serenity

Those are not words typically found in biopharmaceutical literature, but they’re useful here to convey:

• L-theanine promotes relaxation without causing drowsiness
• L-theanine promotes mental alertness without being a stimulant

Here is where l-theanine really stands out from caffeine. If both substances promote mental focus, but one of them does it by making us “wired” and the other does it while simultaneously promoting calm, it makes the choice between them clearer!

Read more: L-theanine, a natural constituent in tea, and its effect on mental state

It relieves stress and anxiety

Building on from the above, but there’s more: l-theanine relieves stress and anxiety in people experiencing stressful situations, without any known harmful side effects… This is something that sets it apart from a lot of anxiolytic (antianxiety) drugs!

Here’s what a big systematic review of clinical trials had to say:

Theanine consumption, stress and anxiety in human clinical trials: A systematic review

L-theanine has other benefits too

We’ve talked about some of the most popular benefits of l-theanine, and we can’t make this newsletter too long, but research also suggests that it…

• Supports healthy weight management
• Reduces inflammation
• Supports immune health
• Helps fight cancer
• May extend lifespan ← this one’s a C. elegans study, but despite being a tiny worm, they actually function very similarly to humans on a cellular level; it’s why they’re used so much for anti-aging research

If you’re interested in this topic, we recommend also reading our previous article on l-theanine—pardon that we hadn’t really nailed down our style yet—but there’s a bunch of useful information about how l-theanine makes caffeine “better” in terms of benefits. We also talk dosage, and reference some other studies we didn’t have room to include today!