Caffeine + L-Theanine Stack

This study developed an optimized processing strategy for γ-aminobutyric acid (GABA) instant white tea (GABA-IT) using GABA-enriched white tea as raw material, systematically characterizing its chemical composition and volatile profile. In contrast to the conventional instant tea production process, this work integrates response surface methodology with spray-drying parameter optimization. This integrated approach enables the simultaneous enhancement of functional components and sensory quality. A response surface design was employed to refine the extraction and spray-drying variables following preliminary single-factor trials, and the optimal parameter combination was subsequently determined (40% ethanol concentration, material-to-liquid ratio of 1:15, extraction time of 3 days, atomization speed of 300 rpm, and inlet temperature of 120 °C); the resulting GABA-IT exhibited significantly improved quality characteristics. Specifically, the GABA content increased by 209% (reaching 4.42 mg/g), and theanine, catechins, and caffeine were enriched by 200-300%. Regarding volatile profiles, processing led to a reduction in esters but an increase in aldehydes and hydrocarbons. Relative odor activity value (rOAV) analysis revealed that epoxy-β-ionone and linalool were the key contributors to the characteristic aroma of GABA-IT. Collectively, this study demonstrates the technical feasibility of producing GABA-rich instant tea with enhanced functional components and improved sensory quality, providing practical guidance for the large-scale industrial production of functional tea beverages.

BACKGROUND: Chronic stress is known to impair emotional regulation and adaptive behavioral responses through neuroinflammatory activation, oxidative imbalance, and dysregulation of neuroplasticity-related genes. Kiperin Mind Focus, a nootropic nutraceutical containing L-theanine, citicoline, phosphatidylserine, Rhodiola rosea, Ginkgo biloba, caffeine, and Lion's Mane mushroom extract has been formulated to support stress resilience, mood regulation and neural health. This study aimed to investigate the neuroprotective and neuroregulatory effects of the combined formulation on behavioral, biochemical, histopathological, and molecular parameters in rats exposed to chronic unpredictable mild stress (CUMS). METHODS: Thirty-two adult male Wistar rats were randomized into four groups (n = 8): Control, Stress, Kiperin Mind Focus (MF), and Stress + Mind Focus (SMF). CUMS was applied for 45 days, and the combined formulation was administered by oral gavage (130 mg/kg/day). Behavioral outcomes were evaluated using the sucrose preference (SPT), open field (OFT), elevated plus maze (EPM), and forced swim (FST) tests. Serum and tissue cytokine levels (IL-1β, IL-6, IL-10, TNF-α) and oxidative stress index (TOS/TAS ratio) were measured. Hippocampal and prefrontal gene expression of FOS, DBH, NMB, BDNF, CREB1, GRIN2A, and GABRB1 was assessed via qPCR, and histopathological changes were semi-quantitatively scored. RESULTS: Chronic stress induced anhedonia, anxiety-like behavior, and behavioral despair, accompanied by elevated proinflammatory cytokines, oxidative imbalance, and neuronal degeneration in the hippocampus and prefrontal cortex. The supplementation significantly improved SPT, OFT, EPM, and FST performance, normalized cytokine and oxidative parameters, and reduced neuronal injury scores. At the molecular level, supplementation attenuated stress-induced upregulation of FOS, DBH, and NMB while maintaining neurotrophic (BDNF, CREB1) and GABAergic (GABRB1) expression near control levels. CONCLUSION: Kiperin Mind Focus exerted robust neuroprotective, anti-inflammatory, and antioxidant effects under chronic stress, restoring molecular homeostasis and stabilizing stress-relat

INTRODUCTION: Modern athletic performance is driven not only by physical capacity but also by rapid decision-making, attentional control, and visuomotor coordination. Evidence regarding the acute effects of caffeine (CAF), L-theanine (TEA), and their combination remains inconsistent, particularly with respect to their combined influence on physical and cognitive performance in athletic populations. This study examined the acute effects of isolated and combined CAF and TEA supplementation on maximal strength, intermittent aerobic endurance, and eye-hand coordination in competitive athletes. It was hypothesized that the combined ingestion of CAF and TEA would differentially affect physical performance and eye-hand coordination outcomes compared with isolated CAF or TEA intake. METHODS: Twenty trained athletes completed four randomized, double-blind, placebo-controlled crossover conditions: CAF (3 mg·kg-1), TEA (200 mg), CAF+TEA (COM), and placebo (CON), with ≥72 h washout. Outcomes included isometric leg, back, and handgrip strength; Yo-Yo Intermittent Endurance Test Level 1 performance; and visuomotor coordination (CogniFit®). Data were analyzed using repeated-measures ANOVA with Bonferroni corrections (α = 0.05). RESULTS: Condition effects were found for leg strength (p = 0.004, ηp2 = 0.24) and back strength (p = 0.008, ηp2 = 0.19). In the COM condition, no additional or synergistic effect on maximal strength was observed. Additionally, no significant difference was found between the conditions in aerobic endurance, maximum isometric handgrip strength, and hand-eye coordination results. Caffeine ingestion did not differ from placebo for any strength outcome under the present conditions. Finally, acute ingestion of TEA was associated with reduced maximal isometric leg and back strength compared with CAF and CON. DISCUSSION: Findings challenge the prevailing assumption of CAF + TEA synergy and underscore the need for task-specific interpretation of co-supplementation strategies. Future studies should evaluate dose-response interactions, habitual caffeine intake, sex-specific responses, and broader cognitive domains beyond visuomotor control. The randomized control

The quality of green tea is closely related to its growing environment, especially the altitude. In the present study, the intrinsic relationship between green tea raw materials and altitude was investigated by using machine learning in chemometric analysis. Forty-six Camellia sinensis cv. Longjing 43 (LJ43) samples from three altitude ranges (U500, 500-799, H800) were collected and the basic component analysis and non-target metabolomics were conducted. Results revealed significant altitude-dependent trends that tea polyphenols, total catechins (EGCG, EC, C, GC, EGC), and caffeine decreased with the increasing altitude, while the total free amino acids include theanine, soluble sugars, ECG, and CG increased. Additionally, seventy-four altitude-specific metabolites were identified by using dual thresholds of VIP ≥ 1 and P < 0.05, and the multiple machine learning algorithms were further employed to classify the altitude of raw materials. On the test set, the Random Forest (RF) model achieved the highest accuracy of 97.5 %, outperforming Support Vector Machine (SVM) at 95.24 % and K-Nearest Neighbors (KNN) at 82.5 %. The RF ensemble structure helped reduce overfitting on high-dimensional metabolomic data and quantify feature importance, facilitating identification of key altitude biomarkers such as 1,2,3-tri-O-galloyl-β-d-glucose and Galloylprocyanidin B4. In contrast, linear SVM struggled with nonlinear patterns, while KNN was adversely affected by the irrelevant features. This study demonstrated that metabolites were closely related to the altitude. Nontargeted metabolomics analysis coupled with machine learning functions as a powerful approach to establish chemical fingerprint maps of raw materials and their environment.

Non-alcoholic fatty liver disease (NAFLD) represents a significant global health challenge with limited therapeutic options. Tea consumption has emerged as a promising preventive and therapeutic strategy, yet a systematic and integrative understanding of its mechanisms is lacking. This review employs a novel tripartite approach-combining bibliometric analysis, network pharmacology, and an in-depth literature review-to comprehensively elucidate the multi-faceted role of tea in combating NAFLD. The bibliometric analysis identifies 'inflammation,' 'steatosis,' 'insulin resistance,' and 'gut microbiota' as the core research hotspots. Network pharmacology predicts that tea's active constituents target key proteins (e.g., VEGFA, CDK1) to regulate pivotal pathways like P53 and cancer signalling. We further synthesise evidence on how specific components, such as EGCG and yellow tea polysaccharides, modulate pathways including NF-κB and FXR to alleviate oxidative stress, inflammation, and hepatic steatosis. A central mechanistic insight elucidated in this review revolves around the gut-liver axis. We emphasise that despite their low systemic bioavailability, tea polyphenols exert potent prebiotic-like effects. They are metabolised by the gut microbiota into smaller, more bioavailable phenolic acids and other metabolites that retain or even enhance bioactivity. Furthermore, tea polyphenols, polysaccharides, caffeine, and theanine collectively modulate microbial community structure, enhance the production of beneficial metabolites such as short-chain fatty acids, and reinforce intestinal barrier function, thereby collectively ameliorating the progression of NAFLD. This consolidated mechanistic framework not only provides a comprehensive understanding of tea's anti-NAFLD effects but also highlights the significant potential for developing targeted, tea-based nutraceuticals and pharmaceuticals. Moreover, it establishes a scientific basis for guiding scientifically informed tea consumption practices for the management of NAFLD. © 2025 John Wiley & Sons Ltd.

Tea cultivar and growing altitude are key factors shaping tea quality. This study systematically investigated their individual and synergistic effects on the quality of fresh leaves of Zhongcha 108 (ZC108) and Fuyun 6 (FY6), which were collected at altitudes from 442 to 945 m. Chemical analysis revealed that ZC108 had higher levels of amino acids, theanine, sugars, flavonoids, and catechins than FY6. Increasing altitude reduced tea polyphenols, flavonoids, caffeine, and catechins in both cultivars. Non-targeted metabolomics identified 50 cultivar and 40 altitude-associated metabolites. Key metabolic pathways, including phenylpropanoid, purine, and flavonoid biosynthesis, were upregulated with increasing altitude. A significant cultivar × altitude interaction was observed for coumarin. Machine learning achieved 100 % accuracy in cultivar classification (RF: 96.7 %, SVM: 93.3 %, KNN: 90 %), highlighting the cultivar factors dominance. Key biomarkers, such as phenylethanol and 6-O-β-D-fructofuranosyl-d-glucose were identified. These findings provide a basis for tea cultivar identification, origin traceability, and quality control. © 2025 The Authors. Published by Elsevier Ltd.

To date, no comprehensive study has explored the multi-dimensional quality of Ankang selenium-enriched green tea. Herein, 61 Ankang tea samples from four small-scale geographical origins were analyzed using a novel multi-analytical approach combining intelligent sensory evaluation, selenium quantification, and sensometabolomics. Selenium content differed across regions. 89 non-volatiles were absolutely quantified. Flavan-3-ols were most abundant (493.79-1317.04 mg/L), followed by amino acids (406.18-940.11 mg/L), phenolic acids (364.66-901.33 mg/L), alkaloids (355.44-688.72 mg/L), organic acids (121.08-556.10 mg/L), sugars (105.88-511.91 mg/L), flavone/flavonol and glycosides (0.62-48.48 mg/L). Epigallocatechin gallate (EGCG), theanine, theogallin, caffeine, citric acid, maltose, and kaempferol-3-O-glucosylrutinoside were most predominant within each class. Dose-over-threshold (DOT) based taste contribution analysis showed 10 compounds with DOT>1, highlighting rutin, theogallin, EGCG and caffeine as prominent contributors (DOT = 2036.82, 10.44, 7.28, 5.31, respectively). 43 key differential compounds and distinct DOT in astringency, bitterness and umami was revealed across regions. Moreover, the correlation between differential metabolites, selenium, and taste indexes was explored.

Albino cultivars are well suited for producing small-leaf yellow tea because of their unique leaf colour and taste. This study aimed to uncover the chemical basis for the fresh sweet taste and low bitterness/astringency of albino cultivars through metabolomics. We identified 20 core taste compounds, namely 13 flavonoids, 5 amino acids (AAs), and 2 catechins. Compared with the control 'Fudingdabaicha', 'Naibai' contained a higher number of umami AAs (theanine: 45.84 mg/g; glutamic acid: 10.27 mg/g) and lower catechin levels. Quantitative descriptive analysis showed that albino cultivars exhibited stronger umami and sweetness but reduced bitterness and astringency, suggesting that umami compounds can mitigate the perception of bitterness and astringency. Weighted gene co-expression network analysis indicated that AAs are associated with umami taste, whereas flavonoids, catechins, and caffeine influence bitterness and astringency. These findings support the conclusion that the combination of elevated AA levels and reduced catechin levels is the primary driver of the fresh sweet taste of albino cultivars. © 2025 The Authors.

Arbuscular mycorrhizal fungi (AMF) enhance host biomass and nutrient uptake, yet their regulatory mechanisms and gene networks in tea plants remain unclear. This study investigated AMF-induced effects on bud sprouting, selenium (Se) accumulation, secondary metabolite contents, and transcriptome profile changes in tea plants to elucidate these mechanisms. The results showed that AMF accelerated tea bud sprouting by 1 week, increased available Se content in rhizosphere soil and leaves, and elevated l-theanine content while decreasing polyphenols and caffeine levels. The green tea produced under AMF inoculation combined with 100 mg/L Na2SeO3 received the highest sensory score. Differential gene expression analysis identified 980, 3099, and 1044 differentially expressed genes in the comparisons of CK vs Se, CK vs AMF, and CK vs Se + AMF, respectively. These results indicate that AMF promotes earlier bud sprouting─enabling earlier market entry─and improves Se fertilizer use efficiency, thereby reducing input costs. This study provides a theoretical basis for elucidating the molecular mechanisms of tea tree-microbe interactions.

Fertilization is a necessary measure in the cultivation and management of the tea bush, and the use of different fertilizers significantly affects the quality of tea leaves. In this study, 100% chemical fertilizer (CF), 100% organic fertilizer (OF), and 50% chemical fertilizer + 50% organic fertilizer (COF) were used to analyze the effects of different fertilizer treatments on the quality indices and volatile component compositions of tea leaves. The results showed that COF treatment significantly increased the content of water extract, tea polyphenols, theanine, free amino acids, and soluble sugar, but decreased the content of total flavonoids and caffeine, indicating that COF treatment has an advantage in improving the overall quality of tea leaves. Analysis of volatile components showed that different fertilizer treatments significantly affected the content of eleven characteristic metabolites in tea bush leaves, of which four characteristic metabolites were most abundant under CF treatment, eight under OF treatment, and only one under COF treatment. The odor characteristics and their intensity analyses showed that the 11 characteristic volatile components mainly exhibited three types of odor characteristics, such as woody, green, and floral, of which OF treatment enhanced woody and green intensities, while CF treatment enhanced floral intensity. Taken together, different fertilizer treatments could regulate the quality indices and volatile components of tea leaves, while the use of chemical fertilizers or organic fertilizers alone was conducive to enhancing the intensity of individual special odor characteristics in tea leaves. Overall, the combination of chemical fertilizers and organic fertilizers was more conducive to the improvement of tea quality. This study provides a theoretical basis for optimizing the fertilization strategy of tea bushes to improve tea quality.

BACKGROUND: Caffeine is a well-known ergogenic aid that can enhance physical and cognitive performance. However, it often induces side effects, such as anxiety and overstimulation, which can be problematic in high-pressure sports like wrestling. L-theanine, a non-stimulant amino acid found in tea, may help mitigate these effects by promoting a calm yet focused mental state. This study aimed to investigate the acute effects of caffeine, L-theanine, and their combination on physical performance, cognitive function, and anxiety in elite male wrestlers. METHODS: In a double-blind, placebo-controlled, crossover design, 12 elite male wrestlers (21.8 ± 2.1 years) completed four test sessions under randomized conditions: placebo (PLA), caffeine (CAF; 3 mg/kg), L-theanine (THE; 3 mg/kg), and caffeine + L-theanine (CAF+THE; 3 mg/kg each). After 60 minutes, athletes performed the wall-squat test, vertical jump height (VJH), medicine ball throw (MBT), handgrip strength, and the Specific Wrestling Fitness Test (SWFT). Cognitive function was assessed pre- and post-SWFT using a computerized Stroop test. Anxiety was assessed using the State-Trait Anxiety Inventory (STAI), and side effects were recorded. RESULTS: CAF+THE outperformed PLA in wall-squat time (p = 0.001), MBT (p = 0.005), VJH (p = 0.011), and grip strength (p = 0.004). SWFT throw count was highest in CAF+THE versus all other conditions (p < 0.001). Post-SWFT Stroop reaction time was faster in CAF+THE than PLA (p = 0.004) and THE (p = 0.036), and accuracy was also higher (p = 0.009 vs PLA). CAF alone increased state anxiety compared to PLA (p = 0.021), while CAF+THE reduced anxiety to below placebo levels (8% incidence vs 33%). Trait anxiety was lower in CAF+THE compared to CAF (p = 0.018). The prevalence of caffeine-induced tachycardia (92%) was notably reduced under CAF+THE (17%). CONCLUSION: CAF+THE (3 mg/kg each) enhances elite wrestlers' strength, endurance, cognitive speed, and accuracy while reducing anxiety and physiological side effects commonly associated with caffeine alone. This combination represents a safe, practical supplement strategy for combat sports athletes who must maintain explosive performance

L-theanine, an amino acid found in tea, and caffeine, found in tea and coffee, are claimed to enhance attention. We conducted a double-blind, placebo-controlled, counterbalanced, two-way crossover trial to determine the acute effects of a high-dose L-theanine-caffeine combination on neurobehavioural (reaction time) and neurophysiological (P3b cognitive event-related potential (ERP)) measures of selective attention in acutely sleep-deprived healthy adults. Thirty-seven overnight sleep-deprived healthy adults (aged 22-30 years, twenty-one men) completed a computerised traffic-scene-related visual stimulus discrimination task before and 50 min after ingesting 200 mg L-theanine-160 mg caffeine combination or a placebo. The task involved selectively responding to imminent accident scenes (20 % probability) while ignoring randomly intermixed, more frequent safe scenes (80 % probability). A 32-channel electroencephalogram was recorded concurrently to derive ERP. The L-theanine-caffeine combination significantly improved the hit rate (P = 0·02) and target-distractor discriminability (P = 0·047), compared with the placebo. Although both L-theanine-caffeine combination (△ = 52·08 ms, P < 0·0001) and placebo (△ = 13·97 ms, P = 0·024) improved reaction time to accident scenes, the pre-post-dose reaction time improvement of the L-theanine-caffeine combination was significantly greater than that of placebo (△ = 38·1 ms, P = 0·003). Compared with the placebo, the L-theanine-caffeine combination significantly increased the amplitudes and reduced the latencies of P3b ERP component. Our findings suggest that L-theanine-caffeine combination improves the accuracy and speed of deploying selective attention to traffic scenarios in sleep-deprived individuals. This improvement is brought about by greater and faster neural resource allocation in the attentional networks of the brain.

We isolated endophytic bacteria Pseudomonas knackmussii from Camellia sinensis and identified its L-theanine synthesis-related gene, CDF86904.1. Irrigation with endophytic bacteria significantly increased the L-theanine content of tea plants. The presence of L-theanine in tea enhances its sensory attributes and mitigates the bitterness caused by polyphenols and caffeine. The low L-theanine content in summer and autumn teas, which is < 1% of their dry weight, is a key factor in their inferior taste. Our study successfully enhanced L-theanine levels in tea plants by irrigating them with endophytic bacteria. The Pseudomonas knackmussii isolated from tea plants is notable for its outstanding ability to synthesize L-theanine, using ethylamine to produce 201.4 μM of L-theanine. Our study identified the key gene responsible for the biosynthesis of L-theanine in P. knackmussii to be CDF86904.1 (L-glutamine synthetase, GS). We found that P. knackmussii can penetrate nearly all tea plant tissues and has excellent colonization ability. Additionally, irrigation of Baiye No.1 tea seedlings with both ethylamine and endophytes for 7 days resulted in top leaves exhibiting an L-theanine content of 58.5 mg/g dry weight. This represents a notable increase compared to 37.8 mg/g dry weight with only ethylamine and 15.4 mg/g dry weight with solely water. Surprisingly, after irrigating the tea plants with a combination of endophytic bacteria and ethylamine, the L-theanine content of the third tea leaf was 131.7 mg/g dry weight after 14 days. This study reveals the significant potential of endophytic bacteria in tea plants to increase L-theanine content, providing empirical evidence for improving tea quality and demonstrating important theoretical and practical significance in tea production. © 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

OBJECTIVE: This review aims to assess the efficacy and safety of different supplements, such as L-theanine, caffeine, Ginkgo biloba L., and Bacopa monnieri for improving ADHD symptoms, to determine the most effective supplement and provide insight for medical practice. METHODS: International databases (PubMed/MEDLINE and Scopus) were searched for English-language RCTs, open-label studies, and cross-sectional studies. RESULTS: Studies on L-theanine, caffeine, Ginkgo biloba L., and Bacopa monnieri have shown various effects on ADHD symptoms. L-theanine improved sleep efficiency but not other sleep parameters. Caffeine showed no significant benefits, although its combination with L-theanine may enhance attention. Bacopa monnieri consistently improved inattention, hyperactivity, and memory, whereas Ginkgo biloba L. reduced ADHD symptoms, particularly inattention, but was less effective than methylphenidate. CONCLUSIONS: The evidence revealed the potential use of supplements as complementary ADHD treatments under clinical guidance. The limited effect of supplements cannot replace the well-documented efficacy of stimulants for ADHD treatment. Additional studies are needed to ascertain the most effective dosages and the safety of these supplements as adjunctive treatments for ADHD.

Green tea (Camellia sinensis L.), one of the most popular beverages worldwide, contains caffeine, a natural stimulant. However, some green tea extracts have been known to possess both hypnotic and arousal effects. This study aimed to identify the components influencing these dual effects using a green tea ethanol extract (GE). Response surface methodology revealed that only some extraction conditions significantly induced arousal effects in ICR mice during the pentobarbital-induced sleep test. Among these, extraction with 95% ethanol for 195 minutes achieved the maximum arousal effect, corresponding to a caffeine content of 58.9 mg g-1, comparable to the effects observed with the reference, 25 mg kg-1 of caffeine. In addition, administration of this GE sample significantly increased wakefulness for 3 hours following treatment in C57BL/6N mice, as confirmed through sleep architecture analysis. A correlation analysis of the total phenolic content (TPC) to caffeine ratio in GE found that the intensity of the arousal-inducing effects varied with TPC (R2 = 0.9428). It was also confirmed that the ratio of EGCG to caffeine, major components of GE, was more closely associated with sleep duration (R2 = 0.9034). L-Theanine, known for its sleep-promoting effects, did not independently affect the arousal effects of GE. However, when combined with EGCG, their total content showed a slightly stronger correlation with sleep duration in relation to the caffeine ratio, compared with that of EGCG/caffeine ratio (R2 = 0.9464). Therefore, the balance between TPC and caffeine appears to modulate the stimulant properties of GE, highlighting its potential as both a stimulant and a mild hypnotic agent. Collectively, these findings provide insights into optimizing GE for tailored functional foods based on its polyphenol/caffeine ratio.