Suntheanine vs. L-Theanine: What’s the Difference?

According to a 2024 survey by the American Psychological Association (APA), 43% of U.S. adults reported feeling more anxious compared to the previous year—an increase from 37% in 2023 and 32% in 2022.

This rising trend has been largely attributed to heightened stress levels, with the most commonly cited stressors being current events, economic instability, and gun violence. These alarming statistics highlight the critical state of mental health in today’s society and the urgent need for effective stress-relief solutions.

Are you feeling overwhelmed and searching for a natural way to relieve stress? You may have heard of L-Theanine, but what about Suntheanine? Are Suntheanine and L-Theanine the same, and which one is better?

In this article, we will explore the relationship between Suntheanine and L-Theanine, examine their differences, analyze their effectiveness in stress reduction, and review the scientific evidence behind these two compounds!

L-Theanine: The Science-Backed Relaxant from Tea

What is L-Theanine?

First and foremost, L-Theanine is an amino acid found in green tea leaves and certain types of mushrooms. It was first discovered in 1949 and quickly attracted scientific interest due to its effects on the brain and neurological health.

Unlike most amino acids, L-Theanine does not directly participate in protein synthesis. Instead, it influences the nervous system, affecting neurotransmitter activity.

One of the most unique properties of L-Theanine is its ability to cross the blood-brain barrier, allowing it to directly impact neurotransmitter function. This enables L-Theanine to promote relaxation without causing drowsiness, while also enhancing focus and cognitive function.

Mechanisms of Action

L-Theanine exerts its effects through three primary mechanisms:

Enhancing Alpha Brain Waves:

Supplementing with L-Theanine increases alpha wave activity in the brain, leading to a meditative or pre-sleep-like state. This promotes calmness without drowsiness. Studies have confirmed this effect by observing increased alpha wave activity in the occipital lobe of individuals who consumed 200mg of L-Theanine (Kobayashi et al., 2023) [1].

Regulating Neurotransmitters:

L-Theanine boosts levels of GABA, serotonin, dopamine, and norepinephrine, which helps reduce stress and enhance focus and energy levels for work and study.

A review study published on PubMed conducted on mice demonstrated the mechanism by which L-theanine promotes the release of GABA, as well as dopamine and serotonin in the brain.

The study further revealed that L-theanine stimulates the activation of glutamate receptors—key excitatory neurotransmitters involved in brain response, information processing, and memory formation. The primary receptors affected by L-theanine include AMPA, Kainate, and NMDA (Nathan et al., 2016) [2].

Reducing Cortisol Levels:

Cortisol is a stress hormone that can have negative health effects if elevated for prolonged periods. L-Theanine helps inhibit cortisol secretion in response to stress, making it an effective tool for stress management.

A study reported that: “An estimated sample size of 24 participants revealed a difference in the mean change of salivary cortisol levels of 8.5 nmol/L between the intervention group and the placebo group from baseline to the end of the study.” As the sample size increased, researchers observed a similar trend in cortisol levels between the two groups (Moulin et al., 2024) [3].

Benefits of L-Theanine

Based on these mechanisms, L-Theanine provides several major benefits:

Reduces Stress:

A study involving over 30 adults found that within one hour of L-Theanine consumption, salivary cortisol levels decreased, and after three hours, alpha wave activity significantly increased, particularly in individuals with higher stress levels (White et al., 2016) [2].

Enhances Focus:

In 2020, Kahathuduwa et al. discovered that L-Theanine combined with caffeine improved sustained attention, inhibitory control, and cognitive processing in five boys with ADHD:

“The L-Theanine–caffeine combination enhanced overall cognitive processing and showed trends in improving inhibitory control.” (Kahathuduwa et al., 2020) [5].

Supports Neurological Disorders:

A broad systematic review on the effects of L-Theanine supplementation on patients with mental disorders, including ADHD, concluded:

“Findings from this systematic review suggest that L-Theanine supplementation significantly supports alleviating psychiatric symptoms compared to control groups in individuals with schizophrenia, anxiety disorders, and ADHD.” (Moshfeghinia et al., 2024) [4].

Improves Sleep Quality:

A comparative study on GABA/L-Theanine blends found:

“The GABA/L-Theanine combination had a synergistic positive effect on sleep quality and duration compared to using GABA or L-Theanine alone.” (Suhyeon et al., 2018) [5].

Beyond scientific research, anecdotal reports further reinforce L-Theanine’s benefits. In a Reddit discussion, 57% of users reported positive effects on stress reduction, focus, and sleep. One user noted, “If I take if before having a coffee, I'm noticeably less anxious and jittery."*

Not as "wired" as you say, which honestly is a negative sometimes. I've also taken it alongside magnesium at night and I get pretty good sleep with the pair, but it's not something I do that often and I don't find a use for it outside of those specific cases too often. Like most things, if I take it by itself randomly I would probably not notice anything at all.”*

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Suntheanine: A Closer Look at the Branded Version

Suntheanine is a branded, patented form of L-Theanine developed by Taiyo Kagaku Co., Ltd., which claims it is produced through a fermentation process designed to mimic the natural synthesis of L-Theanine found in green tea.

According to the manufacturer, Suntheanine is marketed as offering higher purity than standard L-Theanine and more consistent quality due to controlled production processes.

Specifically, to produce L-theanine, scientists combine the enzyme glutaminase—extracted from bacteria, molds, yeasts, and other microorganisms—with glutamic acid and several other compounds. The proportions of these ingredients and the overall synthesis process are tightly regulated.

In the final step, the enzyme catalyzes the conversion of glutamic acid into theanine, which is molecularly identical to naturally occurring L-theanine but produced with high purity and under strict quality control—resulting in what is known as Suntheanine.

Scientific studies and expert discussions suggest that Suntheanine has two main benefits:

• Reduces Stress and Promotes Relaxation:

Suntheanine has been shown to reduce anxiety, fatigue, and stress, including physical stress and PMS (premenstrual syndrome). It promotes relaxation without sedation, improving sleep quality and mental alertness (Rao et al., 2007) [7].

• Support for Smoking Cessation:

Several experimental studies involving Suntheanine suggest that this compound may reduce the rewarding effects of nicotine by modulating the nicotinic acetylcholine-dopamine receptor pathway. This research was conducted on mice, and further clinical evidence is necessary before definitive conclusions can be drawn about Suntheanine’s potential in aiding smoking cessation. Nonetheless, its promise in this area cannot be overlooked (Di et al., 2012) [9].

These results come from studies funded by Taiyo Kagaku Co., Ltd.

In a brand-affiliated commentary, Dr. Shawn Talbott noted: “Stress affects many aspects of life...”, suggesting that Suntheanine may support a positive feedback cycle of improved sleep and daily performance. This perspective reflects expert opinion and should not be interpreted as a clinical endorsement.

Suntheanine vs. L-Theanine: Dissecting the Differences (and Similarities)

Currently, there is limited research analyzing the specific differences in effectiveness between L-Theanine and Suntheanine. Some even argue that the distinction between the two is mainly a marketing strategy rather than being based on clinical evaluations. However, we can compare these two compounds based on the following criteria:

Thus, through a preliminary comparison, it becomes clear that Suntheanine holds a slight advantage in terms of stability and purity, though it typically comes at a higher cost than standard L-theanine. On the other hand, L-theanine is widely available, more accessible, and naturally derived—but may carry certain risks related to batch-to-batch consistency and overall product quality.

In terms of efficacy, both L-theanine and Suntheanine appear to deliver similar benefits. However, due to its higher purity, Suntheanine is believed to provide more potent and consistent results.

That said, scientific evidence directly comparing the two remains limited. Therefore, if you're considering either compound as a health supplement, careful and informed decision-making should be your top priority.

Another branded form, AlphaWave® L-Theanine, is also derived from tea leaves and is promoted as having high purity. Although less widely recognized than Suntheanine, some studies have evaluated AlphaWave® at doses of 200–400 mg. (Evans, et. al. 2021) [10].

Related article: Theanine Vs. L-Theanine: Are They The Same Or Different?

Optimizing Theanine Supplementation: Quality Matters Most

Regardless of whether you're considering L-Theanine or Suntheanine, the most important factor should always be product quality and effectiveness. A high-quality supplement ensures optimal benefits while maintaining safety throughout use.

To select a reliable Theanine supplement, consider the following tips:

• Check for Third-Party Certifications: Look for certifications from NSF, USP, or GMP, as these ensure purity and freedom from contaminants.

• Choose Reputable Brands: Opt for brands that provide transparent sourcing, detailed manufacturing processes, and positive user reviews on online marketplaces and health forums.

• Verify Independent Lab Testing: Supplements with third-party lab reports are generally more trustworthy, as they have undergone objective quality verification.

While Theanine supplements are beneficial, maintaining a healthy lifestyle remains key to sustaining mental clarity and well-being. A balanced diet, proper sleep, and stress management are essential for long-term health. Always consult a medical professional before incorporating supplements into your routine.

Conclusion

Both L-Theanine and Suntheanine offer significant neurological benefits, yet there is no strong clinical evidence suggesting major differences between them.

If you're looking for a cost-effective option to promote relaxation, stress relief, and focus, L-Theanine is likely the better choice. However, if you prioritize purity and consistency, Suntheanine may be worth the higher price.

Regardless of your choice, always remember that supplements are not a “magic cure”. A healthy lifestyle remains the most important factor in maintaining mental well-being—and professional guidance can help tailor supplementation to your specific needs.