Lab notes 001: Green tea's nutraceuticals

 

Most of us treat concentration like a fuel problem which can be solved simply by consuming stimulants. The motto: when in doubt just take more. What we are missing is that caffeine is not used by the body as an energy source itself. It is only blocking tiredness for a limited amount of time with a potential for overproportional catch-up effects. When we experience deadline pressure, our bottleneck is not fuel, it is to maintain control.

Nutraceuticals: Natures sources for focus

Nutraceuticals are bioactive compounds derived from food sources that provide physiological benefits beyond basic nutrition, often utilized in concentrated medical forms such as capsules or powders. They remain to be based on natural ingredients and are widely valued for their therapeutic potential, which can positively influence neurological, antioxidant and anti-inflammatory properties. 

Caffeine 

Caffeine (1,3,7-trimethylxanthine) is a naturally occurring purine alkaloid and the most widely consumed psychoactive stimulant globally. It mainly works by blocking adenosine receptors, the body's brake system that gets accumulated during the day. This mechanism can improve alertness and reaction time, but it does not replace sleep or guarantee better cognitive control under stress. 

After a dose, caffeine peaks roughly within 15 to 120 minutes, which explains the quick lift and the equally quick loss of arousal, especially when fatigue is high. When the subjective effect drops, doubling down can lead to overstimulation because caffeine’s average half-life in healthy adults is about 5 hours, so redosing increases total load and raises the chance of tense stimulation and sleep disruption, especially later in the day. [4] 

An interesting fact is that the European Food Safety Authority (EFSA) considers intakes up to 400 mg per day and single doses up to 200 mg as generally safe for healthy adults [10] but according to scientific literature even amounts around one cup of coffee (80-120 mg) can have negative side effects like decreased concentration after consistent usage. [1] 

What caffeine does well, and where it fails:

A) High caffeine pitfalls

• Caffeine mainly blocks adenosine A1 and A2A receptors, boosting arousal and dopamine signaling, but it does not increase focus skills. [2][3]
• Regular daily use of high amounts can drive tolerance via upregulated adenosine pathways, so the same dose stops feeling effective and escalation is more likely. [5][6]
• Cutting back can trigger withdrawal within about 24 hours, including headache, fatigue, low mood, irritability, and worse concentration. [7]
• Higher intakes are linked to higher anxiety risk in meta analyses and can provoke panic symptoms in vulnerable individuals. [8][9]
  

B) Low to moderate caffeine upsides

• Low to moderate acute caffeine can improve alertness and reaction speed when sleepiness is the bottleneck. [11][12]
• It can improve attention, mood, and cognitive performance with low to moderate dosing. [12]
• Some studies suggest that daily coffee may reduce Alzheimer’s risk, with moderate intake as the plausible range rather than more is better. [13]
• While up to 400 mg per day are considered as 'safe', 100 mg can negatively impact sleep in some people depending on timing and sensitivity. [10]

L-theanine: A promising synergy with caffeine

While caffeine can indirectly overstimulate dopamine signaling at higher consumption, GABA (gamma-aminobutyric acid) acts as the brain's main inhibitory neurotransmitter. It functions like a brake to slow down nerve cell activity and produce a calming effect without feeling tired. L-theanine has been found to show certain traits that modulate GABA. 

• L-theanine is a tea derived amino acid that crosses the blood brain barrier and is discussed as supporting inhibitory control, partly via effects on GABA related pathways. [14]
• Much of the evidence for increased brain GABA involves animal models or mixed formulations, so human effects have to be framed cautiously. [14][15][16]
• One controlled human crossover trial showed that an l-theanine based drink reduced stress related symptoms and altered brain activity patterns, supporting a smoother subjective state rather than stronger stimulation. [17]

Pairing caffeine with l-theanine has become popular because of the synergistic effect in combination with caffeine. Controlled human studies are backing up positive cognitive effects between the two nutraceuticals. A common pattern is to moderate caffeine with roughly double the amount of l-theanine. 

Examples from placebo controlled studies:

• 50 mg caffeine plus 100 mg l-theanine improved performance on a visual recognition task and showed brain signals linked to a calmer kind of alertness, with effects not seen from either ingredient alone. [18]
• 40 mg caffeine plus 97 mg l-theanine improved task switching accuracy and increased alertness while reducing tiredness versus placebo, showing evidence for demanding work scenarios. [19]
• 150 mg caffeine plus 250 mg l-theanine improved several reaction time and accuracy measures versus placebo and extended some benefits beyond caffeine alone, while theanine alone showed mixed effects. [20]
• 40 mg caffeine plus 97 mg l-theanine improved speed and accuracy and reduced distractibility versus placebo, while caffeine alone improved alertness and later task accuracy but less consistently on the demanding measures. [21]

Possible conclusions: The evidence supports a real effect on specific attention outcomes in specific contexts. It does not support the claim that any of these ingredients alone guarantee deep work for everyone. As with all supplements, your baseline is the deciding factor. Especially sleep, stress, anxiety, and task type matter most.

Green tea polyphenols: Plausible benefits and safety

EGCG, naturally found in green tea, is one of the plant’s main neuroactive components with distinct mechanisms from caffeine. Evidence shows that it yields protective and potentially cognitive-enhancing effects through dopaminergic modulation, antioxidant activity, and synergistic interactions with other green tea compounds like caffeine and L-theanine.

• EGCG acts beyond simply sacrificing its electrons to free radicals (unstable molecules that damage our cells). Models show that EGCG additionally activates Nrf2 (a cellular stress response switch). This protein turns on "the cell's internal factory" for producing a wide array of powerful and long-lasting protective enzymes, thereby boosting the cell's overall resilience to oxidative stress. [22][23]
  
• Mechanistically, EGCG can modulate dopamine in cells, including effects on dopamine transporter function and trafficking, which may help to explain dopamine related findings. Studies like this are only the first step into delivering robust evidence for a direct dopamine boost in people and more research has to be conducted. [24][23]
• Preclinical Parkinson type studies suggest that EGCG can protect dopaminergic neurons by lowering oxidative stress and neuroinflammation and by activating endogenous defense signaling, but this is not clinical proof of disease prevention. [25][23]

Product safety: Regulators like EFSA report liver injury signals with high dose green tea extract intakes above 800 mg EGCG per day, especially in the form of pills and capsules. Green tea as a beverage is generally considered as safe. Klaris therefore discloses EGCG per serving and relies on a water dissolved format to reduce risk. [26][27][28]

Conclusions about Green Tea's Efficacy for Cognition

In their review on the effects of green tea on mood, cognition and brain function Mancini et al. (2017) summarize that evidence is strongest when multiple tea compounds are present rather than a single isolate. [29]

These findings serve as the foundation upon which we crafted the formulation behind KLARIS - test how you can benefit from green tea's carefully combined nutraceuticals