L-Theanine and Caffeine Synergy

L-Theanine and Caffeine Synergy

The key benefits of taking a pre-workout supplement include experiencing a boosts in focus. This allows you to maintain concentration and make progress, without getting distracted.

But which nutrients deliver the best results for keeping you both focused and motivated? Caffeine and L-Theanine.

Also known as ‘smart caffeine’, the combination of these two nutrients has shown to enhance the benefits of caffeine; keeping you away from unwanted side effects, such as jitters and energy crashes.

Both of these nutrients are found naturally in green tea – but you won’t get a strong enough dose from a single cup.

With this in mind, we’ve formulated 4 Gauge to be more efficient at providing these nutrients with a clinical serving of each.

By the time you’ve read this article, you’ll know:

  • The benefits of caffeine and L-Theanine
  • How they work in synergy
  • The science
  • Are there any side effects?

The Benefits of Caffeine and L-Theanine

Everyone knows what caffeine is. It’s one of the best natural stimulants available.

That energy boost you get when drinking tea, or coffee to get you started in a morning? That’s caffeine.

However, you probably haven’t heard of L-Theanine. But it’s consumed more than you think.

What is L-Theanine?

It’s a relaxing agent that’s most prominently found in green tea.

What does it do?

It enhances the benefits of caffeine in smaller dosages – keeping you away from side effects associated with high dosages of the stimulant.

How They Work in Synergy

Caffeine is a strong stimulant, and L-Theanine is an effective relaxing agent – naturally, these two nutrients work well together.

This results in them forming a ‘smart caffeine’ when consumed together.

Why is this beneficial? 

Although caffeine is an effective stimulant, it can sometimes cause side effects when used in isolation. Usually in the form of jitters or energy crashes, when taken in large dosages.

Here’s where L-Theanine plays an important role.

Studies have shown that this relaxing amino acid can relieve the side effects of caffeine; balancing out the negative effects and giving you an overall feeling of energy and focus.

How does Smart Caffeine boost your workout?

The smart caffeine combination allows you to stay focused on your training session. How does this improve your workout?

It allows you to get more out of each rep with stricter form and higher intensity; this is where the term ‘mind-muscle-connection’ stems from.

Ultimately, more time lifting weights and training, means more progress made on your physique.

Benefits summed up: 

  • L-Theanine cancels the unwanted side effects of caffeine (jitters and energy crashes).
  • ‘Smart caffeine’ combo boosts focus in the gym.
  • Stay focused and motivated for longer.

What Contains This Combination?

The only natural source containing both of these excellent nutrients together are green tea leaves. However, the amount of L-Theanine in green tea isn’t high enough to benefit your workout.

Studies have shown that you need more L-Theanine than caffeine to feel the combined smart caffeine combination. This is impossible to achieve when drinking green tea.


Answer: A cup of green tea usually contains 70 mg of caffeine, and only 35 mg of L-Theanine per cup.

How do I consume enough smart caffeine?

This is why finding supplements that contain optimal amounts of both nutrients is your best option.

4 Gauge has been formulated with this in mind; with both nutrients dosed clinically, 4 Gauge promotes enhanced focus in the gym.

Bottom Line: Taking 4 Gauge is the easiest way of ingesting the smart caffeine combination, as well as providing numerous other benefits.

The Science Behind It

Smart caffeine has been the subject of many scientific studies that have researched its effects – to examine whether this combo delivers its benefits.

These studies proved that both nutrients consumed together boosts:

  • Focus
  • Cognitive Performance
  • Alertness.

Here are a few studies that show the effectiveness of smart caffeine: 

Study 1

In a study by Giesbretcht T et al [1] participants were given dosages of L-Theanine and caffeine, or a placebo. Their cognitive performance was tested shortly after, through multiple tasks.

The study found that the cognitive function of the participants who’d taken caffeine and L-Theanine had significantly improved.

The results:

  • L-Theanine and caffeine significantly improved focus – The participants given dosages of  smart caffeine showed enhanced cognitive performance.

Study 2

A study conducted by Owen GN et al [2] aimed to compare the mental performance of participants who had taken dosages of caffeine, against those who’d been given a placebo.

The participants who’d ingested caffeine and L-Theanine showed faster speed and accuracy, as well as being less distracted, when performing tasks.

The results:

  • Smart caffeine combo improved cognition and prevented distraction – The speed and accuracy of the participants had improved, and they were distracted less.

Are There Any Side Effects?

You’ll be glad to hear that L-Theanine hasn’t shown to be toxic in dosages as high as 4,000 mg per body weight in kg.

This means that an 80 kg person would be safe consuming 320,000 mg of L-Theanine daily [3] – you’ll never be consuming this amount, so L-Theanine is extremely safe, and free from side effects.

However, you should watch your daily caffeine intake – the recommended daily allowance (RDA) for caffeine is 400 mg, so we recommend taking no more than 300 mg dosages, to avoid side effects.

4 Gauge contains 150 mg caffeine per serving, so is free from side effects. It’s even been formulated so you can double up your dose (300 mg for a double dose), on days when you need that extra ‘kick’.

Things To Remember: 

  • L-Theanine is extremely safe – it’s almost impossible to over-dose on it.
  • Don’t consume over 300 mg caffeine servings – this will ensure you avoid side effects.
  • 4 Gauge is free from side effects – it contains 150 mg Caffeine per serving, so you won’t experience any jitters or energy crashes.


L-Theanine is a relaxing agent that takes away the potential side effects of caffeine (jitters and energy crashes), so they’re very beneficial when consumed together.

The smart caffeine combination of both nutrients is a great addition to any pre-workout – it’s proven to boost focus, keeping you concentrated on making progress in the gym.

However, studies has shown that the dose of L-Theanine needs to be higher than caffeine for the combination to deliver its full benefit.

This is why 4 Gauge has been formulated with 200 mg L-Theanine, and 150 mg of caffeine – with these dosages, it’s scientifically proven that you’ll experience enhanced focus during your workout, when taking our pre-workout supplement.


  1. Giesbrecht, T et al. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 2010; 13(6): 283-90
  2. Owen, GN et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci. 2008; 11(4): 193-8
  3. Borzelleca, JF et al. A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats. Food Chem Toxicol. 2006; 44(7): 1158-66

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