What Are the Benefits of Combining L-Theanine and Caffeine?

Plenty of people rely on caffeine to feel sharp and focused.

The problem is that most overshoot the dose. One strong coffee or an energy drink too many, and instead of feeling locked in, they’re jittery, anxious, and mentally all over the place.

That’s where L-theanine comes in.

L-theanine is an amino acid found mainly in tea, and it works as caffeine’s counterbalance. While caffeine ramps you up, L-theanine smooths you out, helping you stay calm, focused, and productive—without the crash or scattered attention.

In this article, you’ll learn how L-theanine and caffeine interact and affect your body. You’ll also discover their benefits, the perfect L-theanine-to-caffeine ratio, and how to find the best caffeine and L-theanine supplement for you. 

Key Takeaways

• L-theanine and caffeine affect your brain in complementary ways. Caffeine stimulates the central nervous system and boosts alertness, while L-theanine promotes calm by balancing neurotransmitters like GABA and serotonin.
• Research shows that combining caffeine and L-theanine improves energy, attention, reaction time, and multitasking ability more effectively than taking either compound on its own. 
• The optimal L-theanine and caffeine ratio is between 1-to-1 and 2-to-1. If you’re taking 100 mg of caffeine, aim for 100-to-200 mg of L-theanine for the best results.
• To get the full benefits of L-theanine and caffeine, look for products with effective doses and high-quality ingredients, like Peak.

Table of Contents

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• How Does L-Theanine and Caffeine Affect Your Body?
• What Are L-Theanine and Caffeine’s Benefits?
• What’s the Perfect L-Theanine Caffeine Ratio?
• How to Find the Best L-Theanine and Caffeine Supplement
• FAQ #1: Can you find L-theanine in energy drinks?
• FAQ #2: Can you drink coffee and theanine?
• FAQ #3: How long does L-theanine last?

How Does L-Theanine and Caffeine Affect Your Body?

Caffeine’s primary effects in the body are to stimulate the central nervous system and block the activity of adenosine, a chemical that causes tiredness. It also increases levels of neurotransmitters like dopamine and acetylcholine, which enhance alertness, attention, and mood.

L-theanine, on the other hand, helps balance the levels of several chemicals in the brain, including glutamate, serotonin, and GABA, all of which affect mood, cognitive performance, and other aspects of mental function.

When combined, caffeine and L-theanine complement each other. Caffeine increases alertness and energy, while L-theanine takes the edge off the potential jitteriness or anxiety, resulting in smoother, more focused mental energy.

What Are L-Theanine and Caffeine’s Benefits?

The combination of L-theanine and caffeine has been shown to improve focus, attention, and mental performance more effectively than either compound alone.

For example, a study published in the journal Nutrition Research found that people reacted faster and were less distracted after taking caffeine plus L-theanine compared to caffeine alone, L-theanine alone, or a placebo.

Similarly, a study published in Nutritional Neuroscience found that supplementing with caffeine and L-theanine significantly improved reaction time and attention compared to taking caffeine or theanine separately or a placebo. 

In a study published in the Journal of the International Society of Sports Nutrition, researchers had elite curling athletes take either caffeine, L-theanine, L-theanine and caffeine, or a placebo before performing a mental task and several precise curling shots. 

The results showed that while taking caffeine or L-theanine alone had a small effect on performance, taking a combination yielded much better results. 

Another study published in Appetite showed that taking L-theanine and caffeine helped people switch between tasks faster and more accurately compared to a placebo, suggesting the combination can improve your ability to juggle different jobs at the same time. 

And in yet another study published in Nutritional Neuroscience, researchers found that combining L-theanine and caffeine improved people’s ability to switch between mentally demanding tasks and ignore distractions.

Several more studies echo these findings, leaving little doubt that supplementing with L-theanine and caffeine sharpens focus and boosts cognitive performance, especially for tasks that require quick thinking and shifting attention. 

Other research also suggests that L-theanine may reduce some of caffeine’s downsides, particularly by lowering the risk of caffeine-induced headaches and reversing its negative effects on brain blood flow.

What’s the Perfect L-Theanine Caffeine Ratio?

Most studies showing benefits from combining L-theanine with caffeine use a L-theanine-to-caffeine ratio of between 1:1 and 2:1.

In other words, if you take 100 mg of caffeine, pair it with 100-to-200 mg of L-theanine.

How to Find the Best L-Theanine and Caffeine Supplement

The supplement market is flooded with caffeine and L-theanine products—but many use generic ingredients and ineffective doses.

Peak is different.

Peak contains clinically effective doses of patented forms of caffeine and L-theanine: Suntheanine®, the most studied form of L-theanine with over 40 peer-reviewed studies supporting its benefits, and PurCaf®, a natural, organic form of caffeine.

It also contains no artificial fillers, food dyes, or other unnecessary junk. And it’s tested in an ISO 17025-accredited lab for purity and potency, has a transparent label with no proprietary blends, and is made in NSF-certified, FDA-inspected, and cGMP-compliant facilities.

In other words, if you want a clean, safe, and potent L-theanine and caffeine supplement to enhance energy, focus, and cognitive performance, try Peak.

FAQ #1: Can you find L-theanine in energy drinks?

Yes. For example, Legion’s energy drink contains 150 mg of both caffeine and L-theanine.

The main difference between an energy drink and a standalone caffeine and L-theanine supplement is what else is in the formula. Energy drinks usually include additional ingredients designed to boost energy or mood, while most caffeine and L-theanine supplements contain only those two compounds.

Another difference is the form: energy drinks are liquids, while L-theanine and caffeine supplements typically come in capsule or tablet form.

READ MORE: Pre-Workout vs. Energy Drink: Which Is Best for You?

FAQ #2: Can you drink coffee and theanine?

Yes—combining L-theanine with coffee is a popular way to get both compounds, especially if you’re using coffee as your caffeine source.

However, L-theanine powder has a distinctive taste—some find it sweet, others bitter—which can alter the flavor of your coffee in unpredictable (and usually unpleasant) ways.

If you’re using L-theanine powder, it’s better to mix it with water and take it just before drinking your coffee for the same benefits without compromising the taste.

FAQ #3: How long does L-theanine last?

Research shows that L-theanine levels peak in the blood around 50 minutes after ingestion, which is when its effects are likely to be strongest. Its half-life is just over an hour, meaning you’ll typically feel the effects for around 2-to-4 hours after taking it.