Tea and health

Health-Promoting Effects of Black Tea: A Narrative Review of Clinical Trials

Black tea, a popular beverage, is rich in polyphenols. However, thorough analyses of clinical trial evidence supporting its health benefits are lacking. This narrative review is aimed at addressing this knowledge gap by synthesizing findings across pivotal clinical domains and identifying critical areas for further investigation. A comprehensive search of PubMed/MEDLINE, PubMed Central, Scopus, Web of Science, and Google Scholar was performed for English-language papers from January 1990 to July 2024, focusing on cardiovascular and metabolic health, as well as cognitive function. Findings from clinical trials indicated that consuming black tea regularly enhances endothelial and vascular health, notably by improving flow-mediated vasodilation. These advantages are largely due to the tea's antioxidant, anti-inflammatory, and gut microbiota-modulating effects, including the promotion of beneficial bacterial species such as Flavonifractor plautii. Effects on metabolic health, such as lipid profiles and glucose metabolism, were inconsistent. However, black tea was linked to improved cognitive function, especially attention and alertness, likely due to caffeine and L-theanine. Despite these promising results, further research is needed to overcome limitations like small sample sizes and short study durations. Future studies should be aimed at standardizing black tea preparations to optimize health benefits.

Coffee and tea consumption and glioma risk: a meta-analysis of cohort studies

Background

Research on the association between glioma risk and coffee and tea consumption remains inconclusive. This study seeks to present a meta-analysis of the relationship between coffee and tea intake and glioma risk.

Method

Relevant cohort studies that collected coffee and tea exposure prospectively were identified through searches of the PubMed, Embase, and Scopus databases. Eligible studies included those providing adjusted relative risk estimates or hazard ratios (HRs) with 95% confidence intervals (CIs), or data sufficient for such calculations. Study quality was evaluated using the Newcastle-Ottawa Scale, while the GRADE system assessed the quality of evidence. The analysis explored glioma risk concerning the highest versus lowest levels of coffee and tea intake, supplemented by a dose-response evaluation using a one-stage robust error meta-regression model.

Results

A total of nine studies, published between 2004 and 2020, were included. In a model comparing the highest and lowest levels of coffee and tea consumption, 3,896 glioma cases were identified among 2,648,468 participants. Correspondingly, the pooled HRs with 95% CIs were 0.98 (0.87-1.09) for coffee and 0.95 (0.86-1.06) for tea, respectively. Furthermore, no evidence of publication bias was detected for either beverage. The dose-response analysis indicated a near "L"-shaped relationship between tea consumption and glioma risk, with the most notable risk reduction observed in individuals consuming more than 2.5 cups of tea per day. However, additional tea intake beyond this threshold did not confer evident risk reduction. According to Grade scoring system, the quality of meta-evidence was classified as "very low" for coffee and "low" for tea.

Conclusion

This meta-analysis provides evidence suggesting a potential inverse association between tea consumption and glioma risk, while no such association was observed for coffee consumption. Given that the evidence for coffee was classified as "very low" and for tea as "low," cautious interpretation of the findings is warranted, and further research is needed to validate these results.

Biological potential and mechanisms of Tea's bioactive compounds: An Updated review

BACKGROUND

Tea (Camellia sinensis) has a rich history and is widely consumed across many countries, and is categorized into green tea, white tea, oolong tea, yellow tea, black tea, and dark tea based on the level of fermentation. Based on a review of previous literature, the commonly recognized bioactive substances in tea include tea polyphenols, amino acids, polysaccharides, alkaloids, terpenoids, macro minerals, trace elements, and vitamins, which have been known to have various potential health benefits, such as anticancer, antioxidant, anti-inflammatory, anti-diabetes, and anti-obesity properties, cardiovascular protection, immune regulation, and control of the intestinal microbiota. Most studies have only pointed out the characteristics of tea's bioactivities, so a comprehensive summary of the pharmacological characteristics and mechanisms of tea's bioactivities and their use risks are vital.

AIM OF REVIEW

This paper aims to summarize tea's bioactive substances of tea and their pharmacological characteristics and mechanisms, providing a scientific basis for the application of bioactive substances in tea and outlining future research directions for the study of bioactive substances in tea.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review summarizes the main biologically active substances, pharmacological effects, and mechanisms and discusses the potential risks. It may help researchers grasp more comprehensive progress in the study of tea bioactive substances to further promote the application of tea as a natural bioactive substance in the medical field.

Perovskite Nanocrystals: Superior Luminogens for Food Quality Detection Analysis

With the global limited food resources receiving grievous damage from frequent climate changes and ascending global food demand resulting from increasing population growth, perovskite nanocrystals with distinctive photoelectric properties have emerged as attractive and prospective luminogens for the exploitation of rapid, easy operation, low cost, highly accurate, excellently sensitive, and good selective biosensors to detect foodborne hazards in food practices. Perovskite nanocrystals have demonstrated supreme advantages in luminescent biosensing for food products due to their high photoluminescence (PL) quantum yield, narrow full width at half-maximum PL, tunable PL in the entire visible spectrum, easy preparation, and various modification strategies compared with conventional semiconductors. Herein, we have carried out a comprehensive discussion concerning perovskite nanocrystals as luminogens in the application of high-performance biosensing of foodborne hazards for food products, including a brief introduction of perovskite nanocrystals, perovskite nanocrystal-based biosensors, and their application in different categories of food products. Finally, the challenges and opportunities faced by perovskite nanocrystals as superior luminogens were proposed to promote their practicality in the future food supply.

Teadenol B as a Component of Microorganism-Fermented Tea Extract Inhibited Breast Cancers by Promoting Autophagy

Breast cancer is a significant threat to life and health, which needs more safe and effective drugs to be explored. Teadenol B is a characteristic chemical component of microbial fermented tea. This study discovered that teadenol B could exhibit obvious inhibitory effects on all four different clinical subtype characteristics of breast cancer cells. Proteomic studies show that deoxycytidine triphosphate deaminase (DCTD), which could block DNA synthesis and repair DNA damage, had the most significant and consistent reduction in all four types of breast cancer cells with the treatment of teadenol B. Considering MDA-MB-231 cells exhibit poor clinical prognosis and displayed substantial statistical differences in KEGG pathway enrichment analysis results, we investigated its impact on the size and growth of MDA-MB-231 triple-negative breast tumors transplanted into nude mice and demonstrated that teadenol B significantly suppressed tumor growth without affecting body weight significantly. Finally, we found that the conversion of LC3-I to LC3-II in MDA-MB-231 increased significantly with teadenol B treatment. This proved that teadenol B could be a strong autophagy promotor, which explained the down-regulation of DCTD to some extent and may be the potential mechanism underlying teadenol B's anti-breast cancer effects. This finding provides new evidence for drinking fermented tea to prevent breast cancer and highlights the potential of teadenol B as a novel therapeutic option for breast cancer prevention and treatment, necessitating further investigations to clarify its exact target and the details involved.

Differences in microbial community structure and metabolic activity among tea plantation soils under different management strategies

Introduction

Microorganisms play an important role in the multifunctionality of soil ecosystems. Soil microbial diversity and functions have a great impact on plant growth and development. The interactions between tea trees and soil microbiota can be linked with planting patterns and management strategies, whose effects on soil microbial community structure and metabolites are still unclear.

Methods

Here we used amplicon sequencing and metabolomic analysis to investigate the differences in soil microbial composition and metabolites among three tea production systems: organic, non-organic, and intercropping.

Results

We detected significant differences among the three systems and found that Firmicutes, Proteobacteria, Acidobacteriota, Actinobacteriota and Chloroflexi were the main bacteria in the three soil groups, although they varied in relative abundance. Acidobacteria bacterium increased significantly in the organic and intercropping groups. For fungi, Ascomycota and Basidiomycota were the main differential fungal phyla. Fungi alpha-diversity in the non-organic group was significantly higher than that in the other two groups, and was correlated with multiple soil physical and chemical factors. Moreover, network analysis showed that bacteria and fungi were strongly correlated. The changes in soil microorganisms caused by management and planting patterns may affect soil quality through corresponding changes in metabolites. Metabolomic analysis showed differences in metabolite composition among different groups. It was also found that the arachidonic acid metabolic pathway was affected by changes in soil microorganisms, and may further affect soil quality in an essential manner.

Discussion

Planting patterns and management strategies may significantly affect soil microorganisms and therefore metabolites. Changes in soil microorganisms, especially in fungi, may alter soil quality by affecting soil physicochemical properties and metabolites. This study will provide new insights into soil quality monitoring from a microbiological perspective.

Causal association between tea intake and risk for gout: a Mendelian randomization study

Background: Gout, an increasingly prevalent form of inflammatory arthritis, is caused by the accumulation of uric acid crystals in joints, resulting in severe pain, swelling and stiffness that adversely affect physical, mental and emotional wellbeing. The management of gout requires a combination of medication and lifestyle modifications. Recent studies suggest that tea intake may reduce the risk of developing gout; however, further research is needed to establish a causal relationship. Methods: In this study, we employed a bidirectional two-sample Mendelian randomization (MR) approach, utilizing genome-wide association study (GWAS) summary statistics, to investigate the causal association between increased tea intake and gout. We meticulously selected instrumental variables (IVs) based on rigorous criteria and employed five different MR methods. Heterogeneity was assessed using Cochran's Q statistic, and pleiotropy was evaluated using the MR Egger intercept and MR-PRESSO tests. Weak IVs were identified using F values. The Phenoscanner database was consulted to exclude single nucleotide polymorphisms associated with confounding factors or outcomes. Results: The study included one dataset related to tea intake (ukb-b-6066) and three datasets related to gout (ukb-b-12765, finn-b-M13_GOUT, and finn-b-GOUT_STRICT). Our forward MR analysis suggest a causal relationship between increased tea intake and reduced risk of gout in all three gout-related datasets [OR (95% CI): 0.9966 (0.9938-0.9993), p = 0.0167; 0.4842 (0.2683-0.8737), p-value = 0.0160; and 0.4554 (0.2155-0.9623), p = 0.0393, respectively]. The reveres MR showed increased risk of gout (ukb-b-12765) was significantly associated with low tea intake according to the IVW analysis [OR (95% CI): 0.0062 (0.0002-0.154), p = 0.0020]. However, this association was not observed in the Finn-b-M13_GOUT and Finn-b-GOUT_STRICT [OR (95% CI): 0.9992 (0.9909-1.0075), p = 0.8453 and OR (95% CI): 0.9996 (0.9932-1.0059), p = 0.8896, respectively]. No significant heterogeneity or potential pleiotropy was detected, and the possibility of weak IVs was also excluded. Conclusion: Our MR analysis suggest a causal relationship between genetically predicted tea intake and a decreased risk of gout. These findings underscore the potential advantages of increasing tea intake for preventing gout. However, further research is needed to validate these results and elucidate the underlying mechanisms.

Essential and Potentially Toxic Elements (PTEs) Content in European Tea (Camellia sinensis) Leaves: Risk Assessment for Consumers

Tea (Camellia sinensis) is the second most consumed beverage worldwide, playing a key role in the human diet. Tea is considered a healthy drink, as its consumption has been linked to a lower risk of cardiovascular disease-related events and death, stroke, metabolic syndrome and obesity. However, several studies have shown that C. sinensis is a hyperaccumulator of Al and other elements that are considered potentially toxic. In the present study, the contents of 15 elements (both essential and toxic) were determined for the first time in tea leaves collected in tea gardens located in six different European countries and processed to provide black and green tea. The results showed that Al was the major toxic element detected, followed by Ni, Cr, Pb, As, Cd, Ag, and Hg. Essential elements were detected in the order of Mn, Fe, Zn, Cu, Co, and Se. Statistically significant correlations (p < 0.05) were found in the distribution of some elements, highlighting mechanisms of synergic or antagonist interaction. Multivariate analysis revealed that geographical origin was the main driver in clustering the samples, while the different treatment processes (black or green) did not significantly affect the contents of elements in the leaves. The estimation of potential non-carcinogenic risk revealed no risk for the consumption of European teas for consumers in terms of potentially toxic elements.

Tea consumption and risk of lower respiratory tract infections: a two-sample mendelian randomization study

BACKGROUND

Observational studies have reported the association between tea consumption and the risk of lower respiratory tract infections (LRTIs). However, a consensus has yet to be reached, and whether the observed association is driven by confounding factors or reverse causality remains unclear.

METHOD

A two-sample Mendelian randomization (MR) analysis was conducted to determine whether genetically predicted tea intake is causally associated with the risk of common LRTI subtypes. Genome-wide association study (GWAS) from UK Biobank was used to identify single-nucleotide polymorphisms (SNPs) associated with an extra cup of tea intake each day. The summary statistics for acute bronchitis, acute bronchiolitis, bronchiectasis, pneumonia, and influenza and pneumonia were derived from the FinnGen project.

RESULTS

We found that genetically predicted an extra daily cup of tea intake was causally associated with the decreased risk of bronchiectasis [odds ratio (OR) = 0.61, 95% confidence interval (CI) = 0.47-0.78, P < 0.001], pneumonia (OR = 0.90, 95% CI = 0.85-0.96, P = 0.002), influenza and pneumonia (OR = 0.91, 95% CI = 0.85-0.97, P = 0.002), but not with acute bronchitis (OR = 0.91, 95% CI = 0.82-1.01, P = 0.067) and acute bronchiolitis (OR = 0.79, 95% CI = 0.60-1.05, P = 0.100). Sensitivity analyses showed that no heterogeneity and pleiotropy could bias the results.

CONCLUSIONS

Our findings provided new evidence that genetically predicted an extra daily cup of tea intake may causally associated with a decreased risk of bronchiectasis, pneumonia, and influenza and pneumonia.

Echinops spinosissimus Turra Root Methanolic Extract: Characterization of the Bioactive Components and Relative Wound Healing, Antimicrobial and Antioxidant Properties

Echinops spinosissimus Turra subsp. bovei (Asteraceae) is a medicinal plant in western Algeria. Traditionally, roots and inflorescences are employed as hypertensive agents and in the treatment of hemorrhoids. The current study evaluates the chemical composition, antioxidant, antimicrobial, and wound-healing properties of the root methanolic extract from E. spinosissimus subsp. bovei. The content of total phenolics, flavonoids, and tannins was determined. In addition, the phenolic profile was typified. The studied plant extract resulted in being primarily composed of Apigenin, Kaempferol, and their derivatives. The total phenolic content was equal to 95.31 ± 2.90 mg GAE/g DW, while the number of flavonoids and condensed tannins was 16.01 ± 0.16 mg CE/g DW and 8.30 ± 0.65 mg CE/g DW, respectively. The methanolic extract was found to exhibit antioxidant activity towards the DPPH radical, with an IC₅₀ of 7.99 ± 0.28 mg/mL and a TAC of 30.30 ± 0.54 mg AAE/g DW, as well as an antibacterial effect, especially against P. aeruginosa. No significant wound-healing property was observed, even though the histopathological observations showed enhanced wound-healing quality. According to our evidence, E. spinosissimus could represent a source of phytochemicals with potential beneficial effects for human health in terms of antioxidant and antibiotic properties, although further investigations on this species are needed.

Healthy Taiwanese Eating Approach (TEA) toward Total Wellbeing and Healthy Longevity

A healthy dietary pattern review for Asian countries is scarce, which is crucial for guiding healthy eating. We reviewed Taiwanese dietary pattern discovery studies. Included were 19 studies, the majority of which employed dimension reduction methods to find dietary patterns associated with various health conditions. To show what is a high or low intake of foods in Taiwan, we also report the average dietary content and the 25th and 75th percentile values of the adult population for six food groups gathered by the Nutrition and Health Survey in Taiwan, 2017–2020. The healthy Taiwanese dietary approach is cohesive across multiple health outcomes occurring at different ages. It is featured with higher intakes of plant-based foods, aquatic foods, and some beneficial ethnic foods (soy products), drinks (tea), and cooking methods (boiling and steaming); lower intakes of fast foods, fatty and processed meats, sugar, salt rich foods/drinks, and fried foods; but with mixed findings for dairy and egg. Yet, the average Taiwanese person consumed many refined staple foods and livestock, but not sufficient vegetables, fruits, whole grains and roots, beans, and nuts. Dairy consumption remains low. In conclusion, Taiwanese discovery studies point to a mortality-lowering total wellbeing dietary pattern consistent with the current knowledge, which discloses potential benefits of soy product, tea, and boiling and steaming.

Natural Products of Plants and Animal Origin Improve Albumen Quality of Chicken Eggs

Albumen quality is recognized as one of the major yardsticks in measuring egg quality. The elasticity of thick albumen, a strong bond in the ovomucin-lysozyme complex, and excellent biological properties are indicators of high-quality albumen. The albumen quality prior to egg storage contribute to enhance egg’s shelf life and economic value. Evidence suggests that albumen quality can deteriorate due to changes in albumen structure, such as the degradation of β-ovomucin subunit and O-glyosidic bonds, the collapse of the ovomucin-lysozyme complex, and a decrease in albumen protein-protein interaction. Using organic minerals, natural plants and animal products with antioxidant and antimicrobial properties, high biological value, no residue effect and toxicity risk could improve albumen quality. These natural products (e.g., tea polyphenols, marigold extract, magnolol, essential oils, Upro (small peptide), yeast cell wall, Bacillus species, a purified amino acid from animal blood, and pumpkin seed meal) are bio-fortified into eggs, thus enhancing the biological and technological function of the albumen. Multiple strategies to meeting laying hens’ metabolic requirements and improvement in albumen quality are described in this review, including the use of amino acids, vitamins, minerals, essential oils, prebiotics, probiotics, organic trace elements, and phytogenic as feed additives. From this analysis, natural products can improve animal health and consequently albumen quality. Future research should focus on effects of these natural products in extending shelf life of the albumen during storage and at different storage conditions. Research in that direction may provide insight into albumen quality and its biological value in fresh and stored eggs.

Preparation of Tea Aroma Precursor Glycosides: An Efficient and Sustainable Approach via Chemical Glycosidation

Tea aroma precursor glycosides are plant-derived natural products with great economic value. However, the preparation of these glycosides remains largely overlooked in the past decades. Herein, we report a mild, efficient, and sustainable chemocatalytic procedure for the production of tea aroma precursor glycosides. During the study of the glycosidation, the catalysts were found to be decisive in the product formation favoring different reaction pathways; in addition, the influence of molecular sieves was elucidated. With regard to these findings, the serious problem of the competing orthoester formation side reaction was successfully overcome with low catalyst loading (1 mol %) and the use of 5 Å molecular sieves, leading to the preparation of a variety of tea aroma precursor β-d-glucopyranosides and β-primeverosides on a gram scale in high yields in an economical way. Taken together, the current approach features catalytic glycosidation with non-toxic and low-cost catalysts, demonstrates highly favorable greenness and sustainability, and promises industrial production of tea aroma precursor glycosides.

Effect of Brewing Water on the Antioxidant Capacity of Green Tea Infusion with DPPH Assay

Brewing water plays a crucial role in flavor and potential healthy functions of tea infusion. In this study, seven water samples with different physicochemical properties were selected to brew green tea. Results showed that the brewing water with higher minerals level and pH value would reduce the yield of catechins in tea infusion, which in turn caused the decrease of antioxidant activity to a large extent. Besides, it was found that EGCG, as a major contributor to the antioxidant activity of green tea infusion, was influenced differently by different metal ions, among which Ca2+/Mg2+ could enhance the antioxidant activity of EGCG solutions with different concentration through synergistic effect, particularly Ca2+, and the effect was more markable at a higher EGCG concentration. These results offered theoretical direction to the selection of tea brewing water for consumers and gave a new sight to the effects of metal ions on the antioxidant capacity of EGCG.

The effects of tea plants-soybean intercropping on the secondary metabolites of tea plants by metabolomics analysis

BACKGROUND

Intercropping, especially with legumes, as a productive and sustainable system, can promote plants growth and improves the soil quality than the sole crop, is an essential cultivation pattern in modern agricultural systems. However, the metabolic changes of secondary metabolites and the growth in tea plants during the processing of intercropping with soybean have not been fully analyzed.

RESULTS

The secondary metabolomic of the tea plants were significant influence with intercropping soybean during the different growth stages. Especially in the profuse flowering stage of intercropping soybean, the biosynthesis of amino acids was significantly impacted, and the flavonoid biosynthesis, the flavone and flavonol biosynthesis also were changed. And the expression of metabolites associated with amino acids metabolism, particularly glutamate, glutamine, lysine and arginine were up-regulated, while the expression of the sucrose and D-Glucose-6P were down-regulated. Furthermore, the chlorophyll photosynthetic parameters and the photosynthetic activity of tea plants were higher in the tea plants-soybean intercropping system.

CONCLUSIONS

These results strengthen our understanding of the metabolic mechanisms in tea plant's secondary metabolites under the tea plants-soybean intercropping system and demonstrate that the intercropping system of leguminous crops is greatly potential to improve tea quality. These may provide the basis for reducing the application of nitrogen fertilizer and improve the ecosystem in tea plantations.

Lobelia trigona Roxb-based nanomedicine with enhanced biological applications: in vitro and in vivo approach

This is the first study to report the green synthesis of Lobelia trigona Roxb-mediated silver nanoparticles (LTAgNPs). The optical and structural properties of the synthesised LTAgNPs were analysed using ultraviolet-visible spectroscopy, scanning electron microscopy, Fourier transform infrared, dynamic light scattering and energy dispersive X-ray. LTAgNps were evaluated for their anti-bacterial and anti-fungal properties against 18 pathogens and exhibited significant inhibition against all the strains tested. LTAgNPs had potential scavenging effects on the DPPH, ^•OH, O₂^•- free radical scavenging assays and reducing power assay. LTAgNps possess strong anti-cancer activity against five human cancer cell lines (A549, MCF-7, MDA-MB-231, HeLa and KB) in a dose-dependent manner. The antiproliferative, anti-inflammatory and genotoxicity effects of LTAgNPs were further confirmed by the lactate dehydrogenase release assay, nitric oxide inhibitory assay and comet assay. Furthermore, the incision, excision and burn wound-healing activity of formulated LTAgNPs ointment was assessed in rats. All the wounds had significant healing in groups treated with LTAgNPs ointment compared to the groups treated with the commonly prescribed ointment (Silverex^TM). This study shows and suggests that the previously unreported LTAgNPs could be used as a nanomedicine with significant biological applications.

Post-diagnostic coffee and tea consumption and breast cancer survival

BACKGROUND

We examined the role of post-diagnostic coffee and tea consumption in relation to breast cancer-specific and all-cause mortality among women with breast cancer in prospective cohort studies.

METHODS

We identified 8900 women with stage I-III breast cancer from 1980 through 2010 in the Nurses' Health Study (NHS) and from 1991 through 2011 in the NHSII. Post-diagnostic coffee and tea consumption was assessed by a validated food frequency questionnaire every 4 years after diagnosis.

RESULTS

During up to 30 years of follow-up, we documented 1054 breast cancer-specific deaths and 2501 total deaths. Higher post-diagnostic coffee consumption was associated with a lower breast cancer-specific mortality: compared with non-drinkers, >3 cups/day of coffee was associated with a 25% lower risk (hazard ratio (HR) = 0.75, 95% confidence interval (CI) = 0.59-0.96; P_trend = 0.002). We also observed a lower all-cause mortality with coffee consumption: compared with non-drinkers, >2 to 3 cups/day was associated with a 24% lower risk (HR = 0.76, 95% CI = 0.66-0.87) and >3 cups/day was associated with a 26% lower risk (HR = 0.74, 95% CI = 0.63-0.87, P_trend < 0.0001). Post-diagnostic tea consumption was associated with a lower all-cause mortality: compared with non-drinkers, >3 cups/day was associated with a 26% lower risk (HR = 0.74, 95% CI = 0.58-0.95; P_trend = 0.04).

CONCLUSIONS

Among breast cancer survivors, higher post-diagnostic coffee consumption was associated with better breast cancer and overall survival. Higher post-diagnostic tea consumption may be related to better overall survival.

Prevalence of musculoskeletal pain and environmental health hazards among tea pluckers of Maddekanda tea estate in Balangoda Pradeshiya Saba Division, Sri Lanka

Background: Tea pluckers in Sri Lanka play a prominent role in supplying tea for the local and foreign demand. Long standing, bearing weight on back, repetitive hand movements, slip and falls due to walking on uneven grounds lead to various health problems among them. Thus, this study was aimed to assess the prevalence of musculoskeletal pain and environmental health hazards among tea pluckers of Maddekanda tea estate in Balangoda area, Sri Lanka. Design and Methods: A descriptive cross-sectional study was carried out among 378 tea pluckers, recruited using simple random sampling method. Data were collected by validated, pretested interviewer administered questionnaire and descriptive and inferential statistical analyses were performed by using SPSS v20. Results: The prevalence of musculoskeletal pain in any region of the body was 68.5% (95% CI 63.6-73.2) among all participants and prevalence of lower back pain 43.4% (95% CI 38.3-48.8) was high compared to other site of pain. Nearly 98.4% had experienced of leech biting during their work as a main health hazard. Participants who had experienced stress (OR=2.12, 95% CI: 1.119-3.764), and worked for more than 20 years (OR=2.28, 95% CI: 1.37-3.81) were nearly 2 times more likely to have musculoskeletal pain when compared to their counterparts. Conclusions: Prevalence of musculoskeletal pain was high among tea pluckers and lower back region was the common site of pain. Leech bite was the other dominant health problem faced by them. Stress, duration of work and age were associated with musculoskeletal pain.

Synchronous fluorescence spectroscopy combined with chemometrics for determination of total phenolic content and antioxidant activity in different tea types

BACKGROUND

The aim of this study is to monitor the antioxidant activity (AA) and total phenolic content (TPC) variations of different kinds of teas depending on the infusion temperature and time by using synchronous fluorescence spectroscopy (SFS) combined chemometrics as a rapid method. In this study, black tea, oolong tea, green tea, and green tea powder (matcha) samples were brewed at 80 °C and 96 °C for 2.5 to 30 min. Synchronous fluorescence spectra were recorded at different wavelength interval (Δλ) values for optimal models. AA and TPC of tea samples were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and Folin-Ciocalteu methods as reference methods, respectively. Partial least square (PLS) method was used for correlation between reference methods and SFS method.

RESULTS

Results showed that SFS combined with chemometrics could be an alternative rapid way to monitor TPC and AA of teas with 0.932 and 0.918 of validation R² values in fermented teas (black tea-oolong) while with 0.961 and 0.860 of validation R² values in non-fermented teas (green tea and green tea powder), respectively. Limit of detection (LOD) and root mean square error of prediction (RMSEP) values were ≤ 6.61 μg mL^-1 and ≤ 17.42, respectively.

CONCLUSION

Based on the lowest R² value (0.860) on TPC analysis, the proposed method is more appropriate for AA analysis of green tea and green tea powder. Furthermore, infusion time was more effective for obtaining different amounts of TPC and AA in fermented tea types while only infusion temperature was effective on green tea and green tea powder samples. Therefore, obtained calibration-validation models gave better results for fermented tea types.

FT-NIRS Coupled with PLS Regression as a Complement to HPLC Routine Analysis of Caffeine in Tea Samples

Daily consumption of caffeine in coffee, tea, chocolate, cocoa, and soft drinks has gained wide and plentiful public and scientific attention over the past few decades. The concentration of caffeine in vivo is a crucial indicator of some disorders—for example, kidney malfunction, heart disease, increase of blood pressure and alertness—and can cause some severe diseases including type 2 diabetes mellitus (DM), stroke risk, liver disease, and some cancers. In the present study, near-infrared spectroscopy (NIRS) coupled with partial least-squares regression (PLSR) was proposed as an alternative method for the quantification of caffeine in 25 commercially available tea samples consumed in Oman. This method is a fast, complementary technique to wet chemistry procedures as well as to high-performance liquid chromatography (HPLC) methods for the quantitative analysis of caffeine in tea samples because it is reagent-less and needs little or no pre-treatment of samples. In the current study, the partial least-squares (PLS) algorithm was built by using the near-infrared NIR spectra of caffeine standards prepared in tea samples scanned by a Frontier NIR spectrophotometer (L1280034) by PerkinElmer. Spectra were collected in the absorption mode in the wavenumber range of 10,000–4000 cm⁻¹, using a 0.2 mm path length and CaF₂ sealed cells with a resolution of 2 cm⁻¹. The NIR results for the contents of caffeine in tea samples were also compared with results obtained by HPLC analysis. Both techniques provided good results for predicting the caffeine contents in commercially available tea samples. The results of the proposed study show that the suggested FT-NIRS coupled with PLS regression algorithun has a high potential to be routinely used for the quick and reproducible analysis of caffeine contents in tea samples. For the NIR method, the limit of quantification (LOQ) was estimated as 10 times the error of calibration (root mean square error of calibration (RMSECV)) of the model; thus, RMSEC was calculated as 0.03 ppm and the LOQ as 0.3 ppm.

Tea plant genomics: achievements, challenges and perspectives

Tea is among the world's most widely consumed non-alcoholic beverages and possesses enormous economic, health, and cultural values. It is produced from the cured leaves of tea plants, which are important evergreen crops globally cultivated in over 50 countries. Along with recent innovations and advances in biotechnologies, great progress in tea plant genomics and genetics has been achieved, which has facilitated our understanding of the molecular mechanisms of tea quality and the evolution of the tea plant genome. In this review, we briefly summarize the achievements of the past two decades, which primarily include diverse genome and transcriptome sequencing projects, gene discovery and regulation studies, investigation of the epigenetics and noncoding RNAs, origin and domestication, phylogenetics and germplasm utilization of tea plant as well as newly developed tools/platforms. We also present perspectives and possible challenges for future functional genomic studies that will contribute to the acceleration of breeding programs in tea plants.

Association between tea consumption and depressive symptom among Chinese older adults

Background

Despite accumulating evidence on the protective effect of tea consumption against depression, studies specifically focusing on the elderly population are yet limited. This paper examined the association between the frequency and duration of tea drinking and depressive symptoms of older adults by gender and age groups, based on a nationally representative sample in China.

Method

The study employed the panel data from 2005, 2008/2009, 2011/2012 and 2014 waves of Chinese Longitudinal Healthy Longevity Survey (CLHLS). We used the frequency and consistency of tea drinking behaviors to identify four types of tea consumption amongst Chinese seniors. Depressive symptoms were assessed by a five-item scale. Linear mixed effects models were applied.

Results

We found that consistent and frequent tea-drinking was associated with significantly less depressive symptoms, and such impact was partially mediated by socioeconomic status, health behavior, physical health, cognitive function, and social engagement. However, the association was only significant for males and the oldest-old, rather than females and younger elders.

Conclusions

Consistent and frequent tea-drinking may effectively reduce the risk of depressive symptoms for the Chinese elderly. The promotion of the traditional lifestyle of tea drinking could be a cost-effective way towards healthy aging for China.

Electronic supplementary material

The online version of this article (10.1186/s12877-019-1259-z) contains supplementary material, which is available to authorized users.

Environmental Factors Variably Impact Tea Secondary Metabolites in the Context of Climate Change

Climate change is impacting food and beverage crops around the world with implications for environmental and human well-being. While numerous studies have examined climate change effects on crop yields, relatively few studies have examined effects on crop quality (concentrations of nutrients, minerals, and secondary metabolites). This review article employs a culturally relevant beverage crop, tea (Camelia sinensis), as a lens to examine environmental effects linked to climate change on the directionality of crop quality. Our systematic review identified 86 articles as relevant to the review question. Findings provide evidence that shifts in seasonality, water stress, geography, light factors, altitude, herbivory and microbes, temperature, and soil factors that are linked to climate change can result in both increases and decreases up to 50% in secondary metabolites. A gap was found regarding evidence on the direct effects of carbon dioxide on tea quality, highlighting a critical research area for future study. While this systematic review provides evidence that multiple environmental parameters are impacting tea quality, the directionality and magnitude of these impacts is not clear with contradictory evidence between studies likely due to confounding factors including variation in tea variety, cultivar, specific environmental and agricultural management conditions, and differences in research methods. The environmental factors with the most consistent evidence in this systematic review were seasonality and water stress with 14 out of 18 studies (78%) demonstrating a decrease in concentrations of phenolic compounds or their bioactivity with a seasonal shift from the spring and /or first tea harvest to other seasons and seven out of 10 studies (70%) showing an increase in levels of phenolic compounds or their bioactivity with drought stress. Herbivory and soil fertility were two of the variables that showed the greatest contradictory evidence on tea quality. Both herbivory and soil fertility are variables which farmers have the greatest control over, pointing to the importance of agricultural management for climate mitigation and adaptation. The development of evidence-based management strategies and crop breeding programs for resilient cultivars are called for to mitigate climate impacts on crop quality and overall risk in agricultural and food systems.

Differential Accumulation of Aroma Compounds in Normal Green and Albino-Induced Yellow Tea (Camellia sinensis) Leaves

Tea (Camellia sinensis) cultivars with green leaves are the most widely used for making tea. Recently, tea mutants with white or yellow young shoots have attracted increasing interest as raw materials for making "high-quality" tea products. Albino teas are generallycharacterized as having metabolites of relatively high amino acid content and lower catechin content. However, little is known about aroma compounds in albino tea leaves. Herein, we compared original normal leaves (green) and light-sensitive albino leaves (yellow) of cv. Yinghong No. 9. GC-MS was employed to analyze endogenous tea aroma compounds and related precursors. Quantitative real time PCR was used to measure expression levels of genes involved in biosyntheses of tea aromas.The total contents of most endogenous free tea aromas, including aroma fatty acid derivatives, aroma terpenes, and aroma phenylpropanoids/benzenoids, and their glycosidically bound aroma compounds, were lower in yellow leaves than in green leaves. The content of the key precursor geranyl diphosphate (GDP) and expression levels of key synthetic genes involved in the formation of linalool, a major aroma compound in cv. Yinghong No. 9, were investigated. Linalool content was lower in albino-induced yellow leaves, which was due to the lower GDP content compared with normal green leaves.

Comparative studies on the hypolipidemic, antioxidant and hepatoprotective activities of catechin-enriched green and oolong tea in a double-blind clinical trial

This study aimed to compare the beneficial effect of catechin-enriched green tea and oolong tea on mildly hypercholesterolemic subjects. Sixty mildly hypercholesterolemic subjects (180-220 mg dL^-1) were enrolled and divided into three groups as catechin-enriched green tea (CEGT), catechin-enriched oolong tea (CEOT) or placebo. The subjects were instructed to drink 2 × 300 mL of CEGT (780.6 mg of catechin), CEOT (640.4 mg of catechin) or placebo beverage for 12 weeks. Drinking CEGT and CEOT significantly decreased (p < 0.05) the body weight, fat, and BMI, lipid peroxidation as well as lipid profile (TC, LDL-c, HDL-c, and TG). Also, intervention with CEGT and CEOT significantly improved (p < 0.05) the oxidative indices (TEAC and GSH) and antioxidant enzymes (SOD, CAT, GPx, and GR). Moreover, ultrasound examination endorsed the hepatoprotective activity of CEGT and CEOT by reverting mild fatty liver to the normal hepatic condition because of antioxidant and hypolipidemic activities. To summarize, both CEGT and CEOT showed similar antioxidant and hepatoprotective activities. However, CEOT displayed superior lipid-lowering activity compared to CEGT or placebo, and hence it could be used to amend the wellness condition of mildly hypercholesterolemic subjects.

Occurrence of Functional Molecules in the Flowers of Tea (Camellia sinensis) Plants: Evidence for a Second Resource

Tea (Camellia sinensis) is an important crop, and its leaves are used to make the most widely consumed beverage, aside from water. People have been using leaves from tea plants to make teas for a long time. However, less attention has been paid to the flowers of tea plants, which is a waste of an abundant resource. In the past 15 years, researchers have attempted to discover, identify, and evaluate functional molecules from tea flowers, and have made insightful and useful discoveries. Here, we summarize the recent investigations into these functional molecules in tea flowers, including functional molecules similar to those in tea leaves, as well as the preponderant functional molecules in tea flowers. Tea flowers contain representative metabolites similar to those of tea leaves, such as catechins, flavonols, caffeine, and amino acids. The preponderant functional molecules in tea flowers include saponins, polysaccharides, aromatic compounds, spermidine derivatives, and functional proteins. We also review the safety and biological functions of tea flowers. Tea flower extracts are proposed to be of no toxicological concern based on evidence from the evaluation of mutagenicity, and acute and subchronic toxicity in rats. The presence of many functional metabolites in tea flowers indicates that tea flowers possess diverse biological functions, which are mostly related to catechins, polysaccharides, and saponins. Finally, we discuss the potential for, and challenges facing, future applications of tea flowers as a second resource from tea plants.

Microbial diversity and component variation in Xiaguan Tuo Tea during pile fermentation

Xiaguan Tuo Tea is largely consumed by the Chinese, but there is little research into the microbial diversity and component changes during the fermentation of this tea. In this study, we first used fluorescence in situ hybridization (FISH), next-generation sequencing (NGS) and chemical analysis methods to determine the microbial abundance and diversity and the chemical composition during fermentation. The FISH results showed that the total number of microorganisms ranges from 2.3×10² to 4.0×10⁸ cells per gram of sample during fermentation and is mainly dominated by fungi. In the early fermentation stages, molds are dominant (0.6×10²~2.8×10⁶ cells/g, 0~35 d). However, in the late stages of fermentation, yeasts are dominant (3.6×10⁴~9.6×10⁶ cells/g, 35~56 d). The bacteria have little effect during the fermentation of tea (10²~10³ cells/g, <1% of fungus values). Of these fungi, A. niger (Aspergillus niger) and B. adeninivorans (Blastobotrys adeninivorans) are identified as the two most common strains, based on Next-generation Sequencing (NGS) analysis. Peak diversity in tea was observed at day 35 of fermentation (Shannon–Weaver index: 1.195857), and lower diversity was observed on days 6 and 56 of fermentation (Shannon–Weaver index 0.860589 and 1.119106, respectively). During the microbial fermentation, compared to the unfermented tea, the tea polyphenol content decreased by 54%, and the caffeine content increased by 59%. Theanine and free amino acid contents were reduced during fermentation by 81.1 and 92.85%, respectively.

Antioxidant Activities of Functional Beverage Concentrates Containing Herbal Medicine Extracts

This study investigated the antioxidant activity of functional beverage concentrates containing herbal medicine extracts (FBCH) using various antioxidant assays, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity, and reducing power assay. The total polyphenolic content of FBCH (81.45 mg/100 g) was higher than Ssanghwa tea (SHT, 37.56 mg/100 g). The antioxidant activities of FBCH showed 52.92% DPPH and 55.18% ABTS radical scavenging activities at 100 mg/mL, respectively. FBCH showed significantly higher antioxidant activities compared to the SHT (DPPH, 23.43%; ABTS, 22.21%; reducing power optical density; 0.23, P<0.05). In addition, intracellular reactive oxygen species generation significantly decreased in a concentration-dependent manner following FBCH treatment. These results suggest that the addition of herbal medicine extract contributes to the improved functionality of beverage concentrates.

Updated association of tea consumption and bone mineral density: A meta-analysis

BACKGROUND

Current studies evaluating the association of tea consumption and bone mineral density (BMD) have yielded inconsistent findings. Therefore, we conducted a meta-analysis to assess the relationship between tea consumption and BMD.

METHODS

The PubMed, Embase, and Cochrane Library databases were comprehensively searched, and a meta-analysis performed of all observational studies assessing the association of tea consumption and BMD. Forest plots were used to illustrate the results graphically. The Q-test and I statistic were employed to evaluate between-study heterogeneity. Potential publication bias was assessed by the funnel plot.

RESULTS

Four cohort, 1 case-control, and 8 cross-sectional studies including a total of 12,635 cases were included. Tea consumption was shown to prevent bone loss [odds ratio (OR): 0.66; 95% confidence interval (CI), 0.47-0.94; P = 0.02], yielding higher mineral densities in several bones, including the lumbar spine [standardized mean difference (SMD): 0.19; 95% CI, 0.08-0.31; P = 0.001], hip (SMD: 0.19; 95% CI, 0.05-0.34; P = 0.01), femoral neck [mean difference (MD): 0.01; 95% CI, 0.00-0.02; P = 0.04], Ward triangle (MD: 0.02; 95% CI, 0.01-0.04; P = 0.001), and greater trochanter (MD: 0.03; 95% CI, 0.02-0.04; P < 0.00001), than the non-tea consumption group.

CONCLUSION

This meta-analysis provided a potential trend that tea consumption might be beneficial for BMD, especially in the lumbar spine, hip, femoral neck, Ward triangle, and greater trochanter, which might help prevent bone loss.

Comprehensive Transcriptome Analyses Reveal Differential Gene Expression Profiles of Camellia sinensis Axillary Buds at Para-, Endo-, Ecodormancy, and Bud Flush Stages

Winter dormancy is an important biological feature for tea plant to survive cold winters, and it also affects the economic output of tea plant, one of the few woody plants in the world whose leaves are harvested and one of the few non-conifer evergreen species with characterized dormancies. To discover the bud dormancy regulation mechanism of tea plant in winter, we analyzed the global gene expression profiles of axillary buds at the paradormancy, endodormancy, ecodormancy, and bud flush stages by RNA-Seq analysis. In total, 16,125 differentially expressed genes (DEGs) were identified among the different measured conditions. Gene set enrichment analysis was performed on the DEGs identified from each dormancy transition. Enriched gene ontology terms, gene sets and transcription factors were mainly associated with epigenetic mechanisms, phytohormone signaling pathways, and callose-related cellular communication regulation. Furthermore, differentially expressed transcription factors as well as chromatin- and phytohormone-associated genes were identified. GI-, CAL-, SVP-, PHYB-, SFR6-, LHY-, ZTL-, PIF4/6-, ABI4-, EIN3-, ETR1-, CCA1-, PIN3-, CDK-, and CO-related gene sets were enriched. Based on sequence homology analysis, we summarized the key genes with significant expression differences in poplar and tea plant. The major molecular pathways involved in tea plant dormancy regulation are consistent with those of poplar to a certain extent; however, the gene expression patterns varied. This study provides the global transcriptome profiles of overwintering buds at different dormancy stages and is meaningful for improving the understanding of bud dormancy in tea plant.

Radical scavenging potentials of single and combinatorial herbal formulations in vitro

Reactive oxygen and nitrogen species (RONS) are involved in deleterious/beneficial biological processes. The present study sought to investigate the capacity of single and combinatorial herbal formulations of Acanthus montanus, Emilia coccinea, Hibiscus rosasinensis, and Asystasia gangetica to act as superoxide radicals (SOR), hydrogen peroxide (HP), nitric oxide radical (NOR), hydroxyl radical (HR), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical antagonists using in vitro models. The herbal extracts were single herbal formulations (SHfs), double herbal formulations (DHfs), triple herbal formulations (THfs), and a quadruple herbal formulation (QHf). The phytochemical composition and radical scavenging capacity index (SCI) of the herbal formulations were measured using standard methods. The flavonoids were the most abundant phytochemicals present in the herbal extracts. The SCI50 defined the concentration (μg/mL) of herbal formulation required to scavenge 50% of the investigated radicals. The SHfs, DHfs, THfs, and QHf SCI50 against the radicals followed the order HR > SOR > DPPH radical > HP > NOR. Although the various herbal formulations exhibited ambivalent antioxidant activities in terms of their radical scavenging capabilities, a broad survey of the results of the present study showed that combinatorial herbal formulations (DHfs, THfs, and QHf) appeared to exhibit lower radical scavenging capacities than those of the SHfs in vitro.

Safety of TeaCrine®, a non-habituating, naturally-occurring purine alkaloid over eight weeks of continuous use

BACKGROUND

Theacrine (1,3,7,9-tetramethyluric acid) is a purine alkaloid found in certain coffee (Coffea) species, fruits (Cupuacu [Theobroma grandiflorum]), and tea (Camellia assamica, var. kucha) that has anti-inflammatory, analgesic, and neuro-locomotor properties. Recent preliminary research has also reported increased feelings of energy, reduced fatigue, and strong effects on improving focus, concentration, and motivation to exercise. The purpose of this study was to examine the safety and non-habituating effects of TeaCrine®, a nature-identical, chemically equivalent bioactive version of theacrine.

METHODS

Sixty healthy men (mean ± SD age, height, weight: 22.9 ± 4.7 years, 183.5 ± 9.2 cm, 86.5 ± 13.7 kg) and women (22.3 ± 4.5 years, 165.2 ± 12.3 cm, 69.0 ± 17.4 kg) were placed into one of three groups: placebo (PLA, n = 20), 200 mg TeaCrine® (LD, n = 19) or 300 mg Teacrine® (HD, n = 21) and ingested their respective supplement once daily for 8 weeks. Primary outcomes were fasting clinical safety markers (heart rate, blood pressure, lipid profiles, hematologic blood counts, biomarkers of liver/kidney/immune function) and energy, focus, concentration, anxiety, motivation to exercise, and POMS measured prior to daily dosing to ascertain potential tachyphylactic responses and habituation effects. Data were analyzed via two-way (group × time) ANOVAs and statistical significance was accepted at p < 0.05.

RESULTS

All values for clinical safety markers fell within normal limits and no group × time interactions were noted. No evidence of habituation was noted as baseline values for energy, focus, concentration, anxiety, motivation to exercise, and POMS remained stable in all groups across the 8-week study protocol.

CONCLUSIONS

These findings support the clinical safety and non-habituating neuro-energetic effects of TeaCrine® supplementation over 8 weeks of daily use (up to 300 mg/day). Moreover, there was no evidence of a tachyphylactic response that is typical of neuroactive agents such as caffeine and other stimulants.