Nootropic Review: L-Theanine


What it is

How it works

My protocol moving forward

L-Theanine has a strong reputation as an anti-anxiety, sleep enhancing, and mood boosting supplement. It’s an amino acid found in green tea that is structurally similar to glutamate, the primary excitatory neurotransmitter in the brain. Because of its similarity to glutamate, theanine’s mechanisms primarily involve the glutamatergic system. However, it doesn’t have an overall agonizing effect on this system.


Theanine antagonizes AMPA/Kainate receptors, agonizes NMDA receptors and inhibits reuptake of glutamate/glutamine. Glutamate is taken into astrocytes where it is turned into glutamine, a glutamate precursor. From there, it is transported back to the presynaptic neuron via a glutamine transporter. Inhibiting this transporter causes a depletion of glutamate stores since the neuron has less glutamine to turn into glutamate.

These effects have an overall reduction in glutamatergic activity, resulting in a decrease in brain activity; that is what gives this compound its anti-anxiety, stress relieving, and sleep enhancing properties. It’s also why it pairs extremely well with caffeine (especially higher than normal doses), and magnesium glycinate before bed.

My Subjective Experience

My experience with theanine has been excellent. I put it to the test in a variety of different situations, and have made it a permanent addition to my supplement stack moving forward (not every day though, I’ll explain my exact use cases in a bit).

I used theanine primarily in the morning with caffeine and before bed. These are the two use cases I’ve found the most benefit from. Yes, it does have an anti-stress/anxiety effect when taken alone, but I don’t struggle with that so I didn’t find much of a use in that regard.

Where I found the most benefit was paired with caffeine, in particular with caffeine dosages larger than my everyday dose. This compound is VERY effective at reducing caffeine jitters. I experimented with different dosages and ratios of theanine:caffeine, and came to the conclusion that theanine quells jitters in a dose-dependent manner. 

For example: if I consume 400mg of caffeine, 200mg of theanine would calm my jitters a little bit, 400 would calm them a little more, but 600+ would eliminate them entirely.

Based on my experimenting, I’ve decided that my ideal theanine dose is 1.5-2 times the amount of caffeine I consumed (i.e. for 300mg caffeine I’ll take 400-600mg theanine). This dosing provides me with a calm energetic focus, without the jittery hyperactivity I’d normally get from a large dose of caffeine. I’ll refrain from use on most days, saving it for when I consume a decent amount of caffeine.

Theanine before bed was a mixed bag for me. Taken by itself I slept horrible (tested this multiple nights), but when taken alongside magnesium glycinate I sleep fantastic. My assumption is that since theanine also acts as an NMDA receptor agonist, taking it without magnesium or glycine can leave you pretty restless. That being said, I will never be taking theanine alone before bed ever again. I sleep miles better with no supplements than I did taking it by itself.

Pre-bed dosing took me a bit to get right as well. I noticed no effects from 200-600mg, and it wasn’t until I took 1 g that I felt it had an effect in helping me fall asleep. That’s where this supplement shines in a sleep context, falling asleep. I referred to the combo of 1g theanine and 750mg magnesium glycinate as an ‘off switch’ for my brain the first time I tried it. Within 30 minutes it was like I put my brain on silent mode. Smoothest transitions to sleep when taking that mini-stack. So that’s how I’ll continue to use it moving forward. Not every night, but as wanted/needed, I’ll take 1g alongside my only every night supplement: 750mg of magnesium glycinate.

My protocol moving forward

My experience experimenting with theanine was fantastic (aside from taking it alone before bed), so I’ve decided to add it to my supplement rotation. This is something I will deploy as needed/wanted, but not every day. I’ll outline my specific use cases and dosages here:

-with caffeine doses exceeding my average daily dose (1.5-2x caffeine dose in mg)

-when i feel like i need to de-stress before bed (1g)

-on random occasion before bed (1g)

-if i find myself exceedingly anxious or stressed during the day (200-400mg)

I want to emphasize that these are my findings after weeks of experimenting with different dosages in various scenarios. If you choose to use theanine, I highly suggest you do some testing and find what works best for you. Biology, and certainly neurobiology, are not one size fits all.


Overall, theanine is a fantastic compound. Its synergies with caffeine and magnesium glycinate are unmatched in my book, and it will be a solid addition to my supplement stack moving forward in the scenarios outlined above.

It’s what I’d consider to be an ‘entry level’ nootropic. It’s cheap, low risk, effective, and has a wide range of use cases. I recommend it, even if just for its synergy with caffeine. Can’t stress how well they pair together.

Theanine’s benefits go further than what’s mentioned here, even providing a decrease in blood pressure among other things, but I chose to focus on its effect in the brain.

Supplementary info

Brand used: Nutricost

Form: Pills

Height & Weight for dosage comparison: 6’2, 190lbs

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