Fatigue is often approached as a simple caffeine problem, yet stable cognitive output depends on more than temporary wakefulness. This lab note examines energy metabolism at the cellular level, focusing on energy support for healthy brain function. It reviews research on polyphenols that interact with oxidative stress, mitochondrial regulation, and the broader metabolic environment in which ATP is produced. EGCG from green tea is discussed as a compound linked to antioxidant defense, stress response signaling, and mitochondrial pathways, while guarana is found to offer a more complex mix of plant compounds whose cognitive and metabolic effects may extend beyond its caffeine content alone. 

Key findings from Lab Note 002

In Lab Note 002, we differentiated arousal from attention control and examined the pathways that either calm or excite neuronal signaling.

While arousal can support performance in physical activities, stable attention is essential for demanding cognitive tasks. The neurological pathways involved are broadly glutamate or GABA related and can be modulated by different nutraceuticals such as L-theanine, taurine, or magnesium.

The current evidence points to L-theanine as the most promising modulator of GABA-related signaling and therefore the strongest candidate for stabilizing caffeine.

Energy Support

Most of us reach for a cup of coffee when we feel tired or unable to concentrate. We look for more energy, and caffeine blocks some of the signals that tell us we are tired. However, there is a profound difference between simple wakefulness and cognitive performance.

While caffeine provides the spark, complex polyphenols such as EGCG from green tea and tannins from guarana may support efficient energy production. Below, we explore the science behind these ingredients and their possible relevance for brain energy metabolism.

Mitochondria: The (brain) cell’s powerhouse

Every one of your thoughts requires energy in the form of a molecule called ATP. This energy currency is produced by tiny power plants inside cells called mitochondria. The brain consumes roughly 20% of the body’s energy, which also means that mitochondrial activity generates a high volume of Reactive Oxygen Species (ROS) as a byproduct of the electron transport chain. When ROS accumulation outpaces the cell’s antioxidant capacity, oxidative stress can damage mitochondrial membranes, contributing to energy depletion and, over time, cellular dysfunction.

Scientific research suggests that EGCG acts on several critical mechanisms in the body:

• First, it functions as a direct scavenger of free radicals such as hydrogen peroxide and hydroxyl radicals. As a byproduct of energy generation, mitochondria produce damaging reactive species. EGCG can neutralize some of them by donating electrons, thereby helping to preserve cellular energy metabolism. [1][2][3]
• It also acts as an activator of nuclear factor erythroid 2-related factor 2 (Nrf2). Once activated, Nrf2 translocates to the nucleus and binds to Antioxidant Response Elements (ARE), upregulating the body’s production of protective enzymes such as glutathione peroxidase and heme oxygenase-1. [4][5]
• EGCG has also been shown to activate AMPK, a key cellular energy sensor involved in metabolic regulation and fuel use, although understanding this as a direct improvement of brain energy supply in humans would go too far. [10][11]
• Lastly, EGCG has been linked to PGC-1α-related pathways involved in mitochondrial biogenesis, the creation of new mitochondria. By stimulating this pathway, EGCG may help cells increase mitochondrial capacity, which is one reason why it is discussed in relation to ATP production and cellular energy support. [4]

Guarana: More than a caffeine source

Guarana is often reduced to a “slow-release” form of caffeine, but the literature suggests a more interesting story. Its seeds contain not only methylxanthines such as caffeine, but also several polyphenols, including catechins such as epicatechin (EC) or larger molecules like tannins. These become relevant as caffeine-induced stimulation rises. The available energy supply to fuel this overcharge depends on how well cells handle the oxidative cost of maintaining output. [6]

Human data suggests that guarana’s catechins are bioavailable and can influence antioxidant enzyme activity and oxidative stress markers after intake. That does not mean guarana directly creates energy, but it supports a more plausible role in protecting the cellular environment in which energy metabolism takes place. In that sense, guarana fits the same broader logic as green tea. It offers more than stimulant input, as its plant compounds may improve how the system tolerates high metabolic demand. [7]

The mitochondrial story should still be considered with care. In preclinical work, guarana has been linked to a higher expression of genes involved in mitochondrial biogenesis and energy expenditure, but those findings come from animal models rather than direct human brain studies. The most rational conclusion to date is therefore modest: guarana may contribute more than caffeine alone because its plant matrix includes compounds relevant to cellular energy handling, even if the exact human mechanism remains only partly understood. [8]

The popular claim that guarana works mainly because its caffeine is released much more slowly through tannin binding is not strongly established in research. It is therefore safer to describe guarana as a more complex source of plant compounds rather than a proven time-release caffeine system. [9]

Summary: Energy and cognitive performance

Caffeine can effectively reduce signals of fatigue, but sustained mental output requires your cells to produce energy cleanly, without accumulating excessive cellular stress. Both green tea and guarana offer plant compounds that support this delicate balance. Consequently, the goal isn't simply to force the body into overdrive, but rather to protect the cellular environment required for stable, long-term focus.

 

These findings serve as the foundation upon which we crafted the formulation behind KLARIS.

 

GET EARLY ACCESS TO KLARIS

 

Read Lab Note 002 about stabilizing caffeine

 

Sources

[1] Schroeder, Emily K., et al. "Green Tea Epigallocatechin 3-Gallate Accumulates in Mitochondria and Displays a Selective Antiapoptotic Effect Against Inducers of Mitochondrial Oxidative Stress." Journal of Neurochemistry, vol. 110, no. 2, 2009, pp. 474–485.
[2] Qin, S., et al. "Cerebral Protection of Epigallocatechin Gallate (EGCG) via Preservation of Mitochondrial Function." Neuropsychiatric Disease and Treatment, vol. 16, 2020.
[3] He, Jinting, et al. “Epigallocatechin Gallate Is the Most Effective Catechin Against Antioxidant Stress via Hydrogen Peroxide and Radical Scavenging Activity.” Medical Science Monitor, vol. 24, 2018, pp. 8198–8206.
[4] Valenti, Daniela, et al. "Epigallocatechin-3-gallate induces oxidative phosphorylation by activating cytochrome c oxidase in human cultured neurons and astrocytes." Oncotarget, vol. 7, no. 7, 2016, pp. 8100-8113.
[5] Pervin, Mst. Shajeda, et al. "Function of Green Tea Catechins in the Brain: Epigallocatechin Gallate and its Metabolites." International Journal of Molecular Sciences, vol. 20, no. 15, 2019, p. 3630.
[6] Schimpl, Fernanda C., et al. “Guarana: Revisiting a Highly Caffeinated Plant from the Amazon.” Brazilian Journal of Pharmacognosy, vol. 23, no. 3, 2013, pp. 401–412.
[7] Yonekura, Lina, et al. “Bioavailability of Catechins from Guaraná (Paullinia cupana) and Its Effect on Antioxidant Enzymes and Other Oxidative Stress Markers in Healthy Human Subjects.” Food & Function, vol. 7, no. 7, 2016, pp. 2970–2978.
[8] Lima, Natália da Silva, et al. “Guarana (Paullinia cupana) Stimulates Mitochondrial Biogenesis in Mice Fed High-Fat Diet.” Nutrients, vol. 10, no. 2, 2018, article 165.
[9] Bempong, D. K., and P. J. Houghton. “Dissolution and Absorption of Caffeine from Guarana.” Journal of Pharmacy and Pharmacology, vol. 44, no. 9, 1992, pp. 769–771.
[10] Collins, Qu Fan, et al. “Epigallocatechin-3-gallate (EGCG), a Green Tea Polyphenol, Suppresses Hepatic Gluconeogenesis through 5′-AMP-activated Protein Kinase.” Journal of Biological Chemistry, vol. 282, no. 41, 2007, pp. 30143–30149.
[11] Potenza, M. A., et al. “Vascular and Metabolic Actions of the Green Tea Polyphenol Epigallocatechin Gallate.” Current Medicinal Chemistry, 2017.