Grüntee (Grüner Tee, roh?, bio?)

The first green tea was exported from India to Japan during the 17th century. It is estimated that about 2.5 million tons of tea leaves are produced each year throughout the world, with 20% produced as green tea, which is mainly consumed in Asia, some parts of North Africa, the United States, and Europe

To produce green tea, freshly harvested leaves are immediately steamed to prevent fermentation, yielding a dry, stable product. This steaming process destroys the enzymes responsible for breaking down the color pigments in the leaves and allows the tea to maintain its green color during the subsequent rolling and drying processes. These processes preserve natural polyphenols with respect to the health-promoting properties. As green tea is fermented to Oolong and then to black tea, polyphenol compounds (catechins) in green tea are dimerized to form a variety of theaflavins, such that these teas may have different biological activities.

Narratives Review

DOI: 10.1186/1749-8546-5-13

Study: weak evidence

Moreover, green tea significantly inhibited OATP1A2-mediated nadolol uptake (half-maximal inhibitory concentration, IC₅₀ = 1.36%).  These results suggest that green tea reduces plasma concentrations of nadolol possibly in part by inhibition of OATP1A2-mediated uptake of nadolol in the intestine.

Randomisierte Crossover-Interventionsstudie

DOI: 10.1038/clpt.2013.241

Study: strong evidence

Tea is among the most consumed nonalcoholic beverages worldwide. Understanding tea flavor, in terms of both sensory aspects and chemical properties, is essential for manufacturers and consumers to maintain high quality of tea products and to correctly distinguish acceptable or unacceptable products. This article gives a comprehensive review on the aroma and off-flavor characteristics associated with 184 odorants. Although many efforts have been made toward the characterization of flavor compounds in different types of tea, modern flavor analytical techniques that affect the results of flavor analysis have not been compared and summarized systematically up to now. Thus, the overview mainly provides the instrumental flavor analytical techniques for both aroma and taste of tea (i.e., extraction and enrichment, qualitative, quantitative, and chemometric approaches) as well as descriptive sensory analytical methodologies for tea, which is helpful for tea flavor researchers. Flavor developments of tea evolved toward time-saving, portability, real-time monitoring, and visualization are also prospected to get a deeper insight into the influences of different processing techniques on the formation and changes of flavor compounds, especially desired flavor compounds and off-flavor substances present at (ultra)trace amounts in tea and tea products.

Narrativer Review in wissenschaftlichem Journal

DOI: 10.1111/1541-4337.12999

Study: weak evidence

. Although green tea is a rich source of bioactive compounds (polyphenols and methyxanthines) the extraction efficiency of these compounds strongly depends on the extraction conditions. The findings of this investigation suggest that maximum extraction eficiency of studied bioactive compounds from green tea is achieved during aqueous extraction at 80 C, for 50 (powder), 150 (bagged) and 300 (loose leaf).

tea samples (2.0 g) were extracted in 200 mL of distilled water (60, 80 and 100 C) and stirred with a glass rod for 3 min

Analytische Studie in wissenschaftlichem Journal

DOI: 10.1016/j.foodres.2009.09.022

Study: weak evidence

The study was done through direct field observations, sweeping net, food trap, sticky trap, light trap and Baermann Funnel method. A total of 71 insect, mite and nematode species was recorded belonging to 45 families under 14 orders. Among these, 25.35% species were foliar insects and mites, 26.76% soil insects and nematodes, 21.13% beneficial insects and 26.76% butterflies. All the foliar and soil insects, mites and nematodes were found as recognized pests of tea. The highest number of individuals among foliar pest was the red spider mite (Oligonychus coffeae) and the lowest number was the coffee red borer (Zeuzera coffeae). Of the soil pests, 77.47% species were termites, 14.33% nematodes, 4.86% field cricket, 2.63% mole cricket and 0.72% cockchafer grub. Regarding the soil pests, live wood termite (Microtermes obesi) was the highest and dagger nematode (Xiphinema sp.) was the lowest in number.

According to pest status, tea mosquito bug, red spider mite, thrips, looper caterpillar, live wood termites, root knot nematode and root lesion nematode were major

In case of beneficial insects, 81.49% species were predators, 16.73% parasitoids and 1.78% parasites. Lady bird beetle (Micraspis discolor) was the highest in number and anthocorids (Anthocoris sp.) were the lowest. Nineteen species of butterflies were found. Of the observed butterflies, lemon emigrant (Catopsilia pomona) was the highest and large oakblue (Arhopala amantes) was the lowest in number.

Beobachtungsstudie - ökolog. Feldstudie

DOI: 10.3329/jbcbm.v3i1.36758

To brew high grade Sencha that has a good balance of sweetness and astringency, use hot water at around 70° C. Prepare small size teapots and teacups, 2-3 grams of tea per-serving, hot water around 70° C; general brewing time is 1-2 minutes. A few points to remember are to warm the cups beforehand, pour brewed tea little-by-little into each cup so that the taste of each serving is even, down to the last drop of tea.Pour the hot water into both teapot and teacups to pre-warm. Discard the hot water from the teapot, put tea leaves, measured for the appropriate number of people, into the teapot. Wait for the boiling water to settle, pour into the teapot as if pulling a string. Wait for about 2 minutes. Discard the hot water from the cups, serve the tea. Make sure to pour the last drop from the teapot. From the second serving, raise the hot water temperature, shorten the brewing time. 

The technique to remember as to how to prepare delicious Gyokuro, is to use lukewarm water of 50° C and slightly more tea leaves. By pouring the warm water slowly, theanine, the key ingredient of gyokuro umami, is drawn out and the rich taste of gyokuro comes alive. The amount of tea leaves per person is 3-4 grams and the leaching time for the first serving is two-and-a-half minutes. Gyokuro should be poured slowly and carefully into a small cup.

Usucha (Light Matcha) Although light tea requires an artistry of fine manners and various tools, you can enjoy casually even in everyday circumstances. A point to remember is that matcha must be strained in advance using a tea strainer. This helps to prevent the tea from lumping up. The per-person serving amount of matcha is 2 scoops, after placing in the cup, pour about 80ml of hot water and mix quickly with a tea whisk until fine bubbles appear.

When tea leaves absorb the moisture, it can cause a deterioration. Also when tea leaves are placed in the environment of high temperature, deterioration will start right away. Once you open the package, try to use them up within 1 month. Keep the tea leaves in the small (less than 100g) jar or can. Keep tea away from the heat or steam and avoid direct sun. How about keeping them in the refrigerator or freezer? There are several things to be careful about when you keep the leaves in the refrigerator or freezer. First of all, since tea has its characteristic of absorbing other smell easily, it is important to keep them in the plastic bag and seal them tight. Secondly, when you take out the package out from the refrigerator, wait until the tea leaves are back to the room temperature before opening the plastic bag. Because of the sudden temperature change, the moisture may occur inside the bag. For you purchased a tea contains a lot of amount tea inside, do not remove them from the package, and cover the whole package with a big plastic bag. If the package is a transparent kind, remove the package, and transform them to the can or jar, and avoid direct sun or the lights. It is also recommended to ask the seller for the tips on the best way to store the leaves. And always remember to keep leaves a way from the heat, smell, light, and humidity.

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Table 1. Pharmacological effects of green tea. mainly in vitro und Rattenexperimente

There are no reports of clinical toxicity on whether there is a health hazard in drinking a large amount of green tea every day. In 2008, Chengelis et al. first conducted safety studies on standardized green tea catechin (GTC) preparations, as well as heat-sterilized (GTC-H) and non-heat-sterilized (GTC-UH) preparations, and found that the level of no observed adverse effects of the three preparations (NOAEL) was 2000 mg/kg/day

Green tea is often developed as a weight-loss beverage, and they are usually considered as safe. However, the United States Pharmacopoeia (USP) has conducted a safety review and counted adverse events (AEs) after the use of high-dose GTE preparations, most of which were liver injury reports.  plasma alanine aminotransferase (ALT) in male CF-1 mice increased 138 times after treatment with high-dose EGCG (1500 mg/kg, i.g., for 7 days). Therefore, they came to the conclusion that high doses of EGCG had a hepatotoxic effect.

500 chemical components have been isolated from tea, including more than 400 organic compounds and more than 40 inorganic compounds.  catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin Gallate (EGCG).myricetin glycosides, quercetin glycosides, and behenyl glycosides. Green tea, as a non-fermented tea, retains the original chemical components of tea completely.

 sugar chain consists of monosaccharides, such as glucose, galactose, rhamnose, arabinose, etc., and disaccharides or trisaccharides. Figure 3. Chemical structures of anthocyanins. gallic acid, chlorogenic acid, caffeic acid, p-coumaric acid, ellagic acid, quinic acid, and tea gallate. Figure 5. caffeine, theophylline, theobromine.

 apoptosis in colon cancer cells by modulating Akt, ERK1/2 and p38 MAPK signaling pathways. It was found that at the highest dose (200 μg/mL), the apoptosis markers caspase-3 and p53 were increased in granulosa cells.

4.2. Anticancer Effects: Inhibiting migration and invasion of tumor cells. Inducing apoptosis. Inhibiting tumor cell angiogenesis. Inhibiting the proliferation of tumor cells.

In particular, the IC₅₀ values of cell viability of HeLa cells at concentrations of 50 μM and 100 μM were 57.2% and 29.3% at 48 h.

target a variety of inflammatory pathways to induce tumor cell apoptosis

As early as 1997, it was reported that green tea extract and its three main components, including tea polyphenols, theanine, and caffeine, have the ability to effectively inhibit copper-catalyzed low-density lipoprotein (LDL) lipid peroxidation. Moreover, Yokozawa T et al. found that the antioxidant activity of green tea extract was in a dose-dependent manner, and the antioxidant activity of the three components was tea polyphenols > theanine > caffeine.  anti-free radical ability of antioxidant compounds contained in green tea was ranked as EGCG > ECG > EGC >

In recent years, there is no doubt that the antioxidant effects of tea polyphenols and catechins in green tea have been extensively studied by scholars all over the world. However, little research has been performed on antioxidants in green tea polysaccharides.

4.4. Antibacterial Effects

Narrativer Review in wissenschaftlichem Journal

DOI: 10.3390/molecules27123909

Study: weak evidence

Green tea possesses antioxidant, anti-inflammatory, anticancer, and antimicrobial activities, reduces body weight, and slows down aging. These effects are primarily attributed to catechins contained in green tea leaves, particularly epigallocatechin-3-gallate. However, in humans, the realization of green tea’s beneficial effects is limited. In order to summarize and critically analyze the available scientific information about green tea’s health benefits and issues related to its use, we conducted an in-depth literature review in scientific databases. A number of in vitro studies reported that green tea catechins modulate various signaling pathways in cells, which is thought to underlie their beneficial effects. However, data on the effects of catechins in humans are scarce, which is partly due to their low stability and oral bioavailability. Furthermore, catechins may also participate in pharmacokinetic interactions when co-administered with certain drugs such as anticancer agents, drugs for cardiovascular diseases, immunosuppressors, etc. As a result, adverse drug reactions or therapy failure may occur. In conclusion, over the years, various approaches have been investigated to optimize catechin intake and to achieve beneficial effects in humans, but to date, the use of catechins for prophylaxis or disease treatment remains limited. Therefore, future studies regarding the possibilities of catechins administration are needed.

Narrativer Review in wissenschaftlichem Journal

DOI: 10.3390/foods14050745

Study: weak evidence

Den Winterblüher hält man bei uns meist in kalten oder temperierten Wintergärten. Aber Vorsicht vor zu viel Licht. Schon als die Kamelienkultur aufkam, hat man spezielle Kamelienhäuser gebaut, bei denen die nach Süden ausgerichteten Wände gemauert sind, um die schattenliebenden Pflanzen vor zu viel Sonne zu schützen. In ihrer Heimat wächst Camellia sinensis in küstennahen Berg- oder Nebelwäldern. Wo ein schattiges Kronendach fehlt, stellt Schattierung die natürlichen Standortbedingungen nach. In Anbauten mit Bodenschluss kann man die Kamelienart auspflanzen. Wird sie als Kübelpflanze kultiviert, steht sie im Sommer gerne im Freien. Wählen Sie auch hier einen schattigeren Platz auf Balkon und Terrasse, in jedem Fall ohne direkte Sonneneinstrahlung. Für Wohnräume ist die Teepflanze ungeeignet.

Camellia sinensis braucht wie alle Kamelien ein sauer wirkendes Substrat, etwa Rhododendronerde. 

In der Vegetationszeit vom Neuaustrieb bis zum Sommer giesst man regelmässig mit kalkfreiem Wasser und düngt alle zwei bis drei Wochen mit einem sauer wirkenden Kameliendünger.

 Suchen Sie einen hellen und kühlen Standort. Die optimalen Temperaturen liegen zwischen zwei und acht Grad Celsius. Die Luftfeuchte sollte mindestens 60 Prozent betragen.

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Over 11 years of follow-up (follow-up rate, 86.1%), 4209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category.

Kohortenstudie

DOI: 10.1001/jama.296.10.1255

Study: moderate evidence

Nine prospective cohort articles involving 465,274 participants and 3694 cases of liver cancer from China, Japan, and Singapore were included. The summary relative risk (RR) indicated a significant association between the highest green tea consumption and reduced risk for liver cancer (summary RR, 0.88; 95% confidence interval [CI], 0.81–0.97). However, no statistically significant association was observed when analyzing daily consumption of one cup (summary RR, 0.97; 95% CI, 0.95–1.00). When stratified by sex, the protective effect of green tea consumption on risk for liver cancer was observed only in the group of women (summary RR, 0.78; 95% CI, 0.64–0.96), but not in men (summary RR, 0.89; 95% CI, 0.79–1.00).

Prospektive Kohortenstudie

DOI: 10.1016/j.nut.2015.05.021

Study: moderate evidence

Compared with non-habitual consumers, participants who consumed > 5 g/day of green tea leaves reduced the risk of CVD by 29% (95%CI: 0.55–0.92), stroke by 30% (95%CI: 0.51–0.95) and coronary heart disease (CHD) by 40% (95%CI: 0.40–0.89). Similarly, participants who consumed green tea for ≥ 40 years reduced the risk of CVD by 31% (95%CI: 0.54–0.88), stroke by 33% (95%CI: 0.50–0.90) and CHD by 39% (95%CI: 0.42–0.88). Among participants with < 5-year history of T2D, > 5 g/day of tea leaves and > 40 years of tea consumption were associated with 59% (95%CI: 0.23–0.72) and 57% (95%CI: 0.26–0.74) reduced risk of stroke, respectively. However, among participants with ≥ 5-year history of T2D, > 5 g/day of tea leaves and > 40 years of tea consumption were associated with a 50% (95%CI: 0.30–0.82) and 46% (95%CI: 0.35–0.85) reduced risk of CHD, respectively.

Conclusions

Green tea consumption is associated with reduced risk of CVD, stroke, and CHD in overweight/obese T2D patients.

Beobachtungsstudie: Kohortenstudie, keine Randomisierung

DOI: 10.1186/s13690-024-01242-3

Study: moderate evidence

Green tea consumption is inversely associated with the risk of stroke.. Moderate green tea drinking (500-1000 ml/d) was associated with a 21% to 24% lower risk of stroke.

Systematische Review + Meta-Analyse, peer-reviewed

DOI: 10.1016/j.nut.2022.111936

Study: strong evidence

The reduction in risk was most evident among those who consistently reported to drink tea regularly at both the baseline and follow-up surveys (relative risk, 0.43; 95% confidence interval, 0.24-0.77). The inverse association with regular tea drinking was observed for both colon and rectal cancers.

Prospektive Kohortenstudie

DOI: 10.1158/1055-9965.epi-07-0097

Study: moderate evidence

The aim of this study is to assess the protective properties of green tea on periodontal health and also to know whether any side effect of green tea prevails in terms of staining of teeth.

Materials and Methods: 

This is a prospective randomized clinical intervention study. Three dependent variables: probing depth (PD), clinical attachment loss (CAL), and bleeding on probing (BOP) were measured to reflect periodontal diseases.

Results: 

The three dependent variables, namely, PD, CAL, and BOP showed statistically significant reductions following introduction of green tea as a conjunct oral hygiene measure in study group as compared to control group.

Conclusion: 

Green tea has shown the antioxidant, antimicrobial, and anticollagenase activities on periodontal health.

Klinische prospektive Studie

DOI: 10.4103/jioh.jioh_37_17

Study: moderate evidence

Tea leaves contain polyphenols of which the majority are catechins with smaller quantities of caffeine, theanine, theobromine, theophylline and phenolic acids. The major catechin in green tea is (−)-epigallocatechin gallate, with lesser amounts of catechin, epicatechin, gallocatechin, gallocatechin gallate and epicatechin gallate [1]. Many of the health benefits of green tea are attributed to the antioxidant capacity of these compounds.

Pharmacokinetic studies suggest a daily dosage of 800 mg/day of epigallocatechin gallate capsules for up to four weeks to be safe and well tolerated.  A daily intake of 3–5 cups per day (720–1200 ml) of green tea will provide at least 250 mg/day of catechins.

Clinical and animal studies indicated that green tea concentrated extracts on an empty stomach is more likely to lead to adverse effects than green tea consumption after eating

The evidence for green tea and cancer risk is inadequate and inconclusive. However there is some positive evidence for risk reduction of breast, prostate, ovarian and endometrial cancers with green tea. RCTs of green tea and cardiovascular risk factors suggest that green tea may reduce low-density lipoproteins and total cholesterol, although studies are of short duration. There is no robust evidence to support a reduction in coronary artery disease risk in green tea drinkers. There are a considerable number of RCTs to suggest that green tea does reduce body weight in the short term, but this not likely to be of clinical relevance. 

Narrativer Review

DOI: 10.1016/j.maturitas.2012.08.008

Study: weak evidence

EGCg is considered one of the natural pan-assay interference compounds (PAINS), due to its catechol motif. PAINS can interfere with numerous bioassays via different mechanisms, rather than the specified target [74]. EGCg has shown promiscuous behaviors in broad bioassays, leading to extensive scientific and medical applications being granted to EGCg along with confusing and conflicting experimental results [74]. While the reactivity of EGCg may generate a protective barrier by readily attacking harmful bacteria and their virulence factors, the pro-oxidant effect of high doses can cause collapse in the mitochondrial membrane potential. Mitochondrial membrane potential is essential for energy storage during oxidative phosphorylation [75]. High doses of EGCg can therefore act as a mitochondrial toxin and lead to severe liver injury [76]. Popularly advertised as dietary supplement, there are increasing numbers of reported adverse events involving the intake of EGCg and concentrated GTE, which contribute to the growing concern of dietary safety and advocacy for FDA regulation. Lambert et al. reported on the dose-dependent hepatotoxic effect of EGCg in mice [77]. A high daily dose of EGCg, administered orally, resulted in cumulative liver damage [76,77]. Acute and chronic hepatitis over time can lead to fulminant liver failure, which ultimately increases mortality [78].

5.1.3. Bioavailability

The potential therapeutic use of catechins is also limited by the poor reported bioavailability of these molecules. In humans, the maximum catechin concentrations in plasma were measured to range from 1 to 2 µmol/L several hours after consumption; this concentration rapidly decreases to baseline levels within 24 hr [79–81]. This low bioavailability was proposed to arise from several factors, including low stability of the catechins within the intestines [82–84], limited transport of catechins across the intestine wall [85,86], and rapid metabolism and clearance

Narratives Review

DOI: 10.3390/pathogens10050546

Study: weak evidence

However, we have reported on 11 patients with green tea–induced asthma, an occupational asthma caused by inhalation of green tea dust, and demonstrated that EGCg is the causative agent.^2–4 Five of the 11 patients also developed food allergy to green tea—ie, their asthmatic symptoms worsened after drinking, as well as after inhaling, green tea. In this communication, we compare the clinical characteristics of these 5 patients with those of the 6 patients whose asthmatic symptoms worsened after the inhalation of, but not after the ingestion of, green tea.

The clinical characteristics of our 11 patients are summarized in Table I. These patients had worked for several years at different green tea factories in Shizuoka Prefecture, the major tea-producing area of Japan, and they had developed nasal and asthmatic symptoms suggestive of an occupational allergy.

Expertenbericht

DOI: 10.1016/S0091-6749(03)01885-2

Study: weak evidence

‘Benifuuki’, a tea (Camellia Sinensis L.) cultivar in Japan, is rich in anti-allergic epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me). ‘Benifuuki’ green tea and simultaneous addition of ginger extract remarkably suppressed cytokine (TNF-α and MIP-1α) secretion from mouse bone marrow-derived mast cells after antigen stimulation and, as expected, suppressed delay-type allergy. After drinking ‘benifuuki’ green tea containing 43.5 mg of EGCG and 8.5 mg of EGCG3″Me, the AUC (area under the drug concentration time curve; min μg/ml) of EGCG was 6.72 ± 2.87 and EGCG3″Me was 8.48 ± 2.54 in healthy human volunteers. Though the dose of EGCG was 5.1 times the dose of EGCG3″Me, the AUC of EGCG3″Me was higher than that of EGCG. A double blind clinical study on subjects with Japanese cedar pollinosis was carried out. At the 11th week after starting the study, in the most severe cedar pollen scattering period, symptoms, i.e., blowing the nose and itching eyes, were significantly relieved in the ‘benifuuki’ intake group compared with the placebo group, and blowing the nose, itching eyes and nasal symptom score, and at the 11th and 13th weeks, stuffy nose, throat pain and the nasal symptom medication score were significantly relieved in the ‘benifuuki’ containing ginger extract group compared with the placebo group. These results suggested that over one consecutive month, drinking ‘benifuuki’ green tea was useful to reduce some of the symptoms from Japanese cedar pollinosis, and did not affect any normal immune response in subjects with seasonal rhinitis, and the ginger extract enhanced the effect of ‘benifuuki’ green tea.

Kombination aus In-vitro-Labor- und Humanstudie mit doppelblindem Studiendesign

DOI: 10.1007/s10616-007-9112-1

Study: moderate evidence

Green tea is sourced from Camellia sinensis (L.) O. Kuntze (Theaceae), the same species from which white, oolong, black and pu-erh teas are derived. The various tea types are classified on the basis of their processing, and the associated oxidation and fermentation levels which influence taste and aroma profiles. Green tea is a minimally oxidized and non-fermented tea

Caffeine contributes to green tea’s stimulant properties, while the amino acid theanine contributes to its relaxing properties. 

China is the center of origin of green tea production.

The tea plant naturally grows in the understory of broad-leaved evergreen forests at altitudes between 100e2,200 m. The native tea growing area, or ‘tea belt’, encompasses southwestern China (Yunnan, Sichuan, Guangxi and Guizhou provinces), northern Laos, northern Vietnam, Myanmar, Cambodia and northeastern India. Some forest-growing tea plants are also found outside of the tea belt in eastern China, Japan, southern Korea, Thailand and Taiwan. The center of diversity of Camellia sinensis is in the Upper Mekong River region of Yunnan Province of southwestern China (Chen and Pei, 2003; Chen et al., 2005). Today, tea plants are primarily found in terraced landscapes in the tea belt and other tropical, subtropical and temperate regions where tea cultivation has been introduced, including Sri Lanka, Indonesia, central Africa, Turkey, Argentina and Russia. 

Camellia sinensis is an evergreen tree or shrub. It has yellow-white flowers and long, serrated leaves. Flowers are axillary, solitary or up to three in a cluster. They are 2.5e3.5 cm in diameter and have six to eight petals. Young leaves have short white hairs on their underside. Flowering of Camellia sinensis occurs from October through February and fruiting occurs from August to October. The tea plant belongs to the Theaceae botanical family

suitable for warm, tropical and sub-tropical environments (Banerjee, 1992). Individuals of the small-leaf variety grow as shrubs or dwarf plant forms and are more suitable for colder, temperate climates . Commercial tea is primarily produced from the former two varieties, Camellia sinensis var. assamica, or the broad-leaf variety of the tea plant, and Camellia sinensis var. sinensis, or the smallleaf variety of the tea plant.

Tea has been cultivated for at least 1,500 years. Cultivation of tea is possible in areas that
receive over 120e150 cm of rain annually, and have temperatures of 12e30
C. Optimum
growing conditions are 250e300 cm annual rainfall and average temperatures of 18e20
C
(Williges 2004). Cultivation may occur from sea level to 2,200 meters, with some tea cultivars
found as high as 3,000 m. Higher altitudes are often associated with higher tea quality. At least
five hours of direct or 11 hours of indirect sunlight daily are required for tea cultivation. Soils
must be well drained, sandy, thoroughly aired, deep and nutritious with a healthy layer of
humus and low pH. Drought, water logging, excessive heat and frost are harmful for the
growth of tea plants and may result in a lower quality product in terms of chemistry, taste,
aroma and bioactivity. Tea plants are often raised in controlled nursery conditions or other
protected conditions for their first two to four years. They are classified as immature at this time
and are not harvested. Once tea plants mature, they are transplanted to the field and are ready
for harvest.

Tea plants cross-pollinate and are self-incompatible

The majority of tea plants cultivated globally are grown in compact rows and are pruned as
roughly rectangular shrubs at a height of 1e1.2 m in what is termed a picking or plucking table Formation of a plucking table serves to expedite harvest and to maximize yields
per area.

Most green tea types are produced using young, tender leaves. The leaf unit harvested varies with the specific type of green tea. Many green tea types include the terminal bud, the internodes and one to three leaves immediately below the bud (Figure 2.2). For some other green tea types, the harvested unit consists of a single young leaf. Older leaves are generally not used to produce high-quality green teas because these leaves are rough with an astringent flavor. Tea leaves are plucked by hand or are mechanically harvested by a plucking machine. Many high-quality green teas are hand plucked. Farmers may hand pluck up to 30 kilos of fresh tea leaf per day. Hand plucking is the most labor intensive and expensive process in tea cultivation and has been replaced in many instances by mechanized pluckers to increase labor productivity and decrease labor costs. Leaves are plucked from the same plant at intervals of four days to two weeks.

Many high-quality teas consist of the terminal bud, internodes and two to three leaves immediately below the bud

Following harvest, tea leaves for green tea production may be spread out on bamboo mats or other surfaces for one to three hours. Not all green tea types involve spreading leaves post harvest. Approximately 30% of moisture content is lost during the spreading process and prepares the leaf for the next step of processing involving heat application

Fresh tea leaves are exposed to heat for approximately 10e15 minutes in a process known as
fixing. Fixing deactivates enzymes in leaf shoots in order to prevent oxidation and fermentation and to maintain a green color. Tea shoots contain enzymes which are responsible for the
biochemical metabolic pathways that cause the growth of tea plants.  Fixing also serves to dry tea leaves. Approximately 40%
of the water content is lost from leaves during fixing (Zhen, 2002).
Fixing methods for green tea include pan-frying and steaming. The pan-frying method involves
placing leaves directly on a dry pan exposed to a high heat source. Steaming involves placing leaves over perforated steamers that release steam blasts from heated water. This is the prevalent fixing method in Japan. 

Fast, even and high-temperature fixing is a feature of green tea processing, and is important for high-quality tea Fixing temperatures range from 100e200
C for artisanal-processed green teas and 220e330
C for machine-fixed green teas

Following fixing, leaves are rolled in order to disrupt their cell walls, release leaf moisture and shape the final product. Rolling times vary between ten minutes and one hour. Rolled tea leaves are shaped into various forms including twists, round, flat, needle, flaky, compressed and ground powder. The grade of tea is commercially judged by the size of the leaf pieces. Whole buds and young leaves are a superior grade to the broken leaf pieces, which are called fannings, and the dust found in many mass-produced teabags. Finally, the shaped leaves are dried by pan-drying, basket-drying, sun-drying or baking. Depending on the method, drying takes from twenty minutes to overnight. Pan-drying produces a tea product with a tighter shape that maintains greater aroma compared to tea that is air-dried in sunlight

Storing tea in sealed packaging in cool dark conditions helps increase its shelf life. There is significant reduction of polyphenolic catechin levels during storage within six months of production of up to 50% decrease of some compounds.

Historically, green tea was prepared as an extracted soup from pressed tea cakes and water. Salt was added to heighten aroma. Drinkers consumed the tea leaves in the soup along with the infusion. Today, green tea is primarily prepared by steeping loose tea leaves or a tea bag in hot water and drinking the infusion

Tea plants have a number of naturally occurring predators including the short-hole borer beetle (Xyleborus fornicatus), red spider mite (Oligonychus coffeae), coccinellid and staphylinid larvae, lace-wing larvae, and Typhlodromus and Phytoseius mites

DOI: 10.1016/B978-0-12-384937-3.00002-1

Book: weak evidence

Traditional herbal medicinal product for relief of fatigue and sensation of weakness

Overdose (quantities corresponding to more than 300 mg caffeine or 5 cups of tea as a beverage) can lead to restlessness, tremor, and elevated reflex excitability. The first signs of poisoning are vomiting and abdominal spasm

a) Herbal tea 1.8 – 2.2 g of whole or comminuted herbal substance in 100 – 150 ml of boiling water as a herbal infusion, 3 – 5 times daily. b) powdered herbal substance Single dose: 390 mg, 3 times daily (up to 5 times if necessary) The use in children and adolescents under 18 years of age is not recommended (see section 4.4 ‘Special warnings and precautions for use’.

The use in children and adolescents under 18 years of age has not been established due to lack of adequate data In the absence of sufficient data, the use during pregnancy and lactation is not recommended. Not recommended before bedtime as it may cause sleep disturbances

Contraindications: Hypersensitivity to the active substance(s). Gastric and duodenal ulcers, cardiovascular disorders such as hypertension and arrhythmia, hyperthyroidism.

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The mean daily intake of EGCG resulting from the consumption of green tea infusions ranges from 90 to 300 mg/day while exposure by high-level consumers is estimated to be up to 866 mg EGCG/day. 

However, rare cases of liver injury have been reported after consumption of green tea infusions, most probably due to an idiosyncratic reaction. 

Panel concluded that there is evidence from interventional clinical trials that intake of doses equal or above 800 mg EGCG/day taken as a food supplement has been shown to induce a statistically significant increase of serum transaminases in treated subjects compared to control.

Narrativer Expertenbericht

DOI: 10.2903/j.efsa.2018.5239

Study: weak evidence

The results showed that the carbon emission intensity of green tea for its entire life cycle was 32.90 kg CO₂eq kg⁻¹ dry tea, and the carbon emission intensities of its consumption, processing, and cultivation were 14.90, 7.94, and 6.97 kg CO₂eq kg⁻¹, respectively. In the processing stage, emissions during steaming and drying accounted for 57%. The use of coal, complicated processing procedures, and older equipment were the main reasons for the high emissions in the processing stage. In the cultivation process, emissions mainly came from fertilizer production and its application in the field. The energy consumption of boiling water resulted in high carbon emissions in the consumption stage.

Ökolog. Life-Cycle-Assessment-Studie

DOI: 10.3390/agronomy13020364

The water footprint of coffee (130 l cup−1 , based on use of 7 gram of roasted coffee per cup) is much larger than the water footprint of tea (27 l cup−1 , based on use of 3 gram of black tea per cup)

Green and black tea: green: 7232, blue: 898, grey:726, total: 8856

Umwelt-Ressourcen-Analyse

DOI: 10.5194/hess-15-1577-2011

was assumed that an exact amount of 170 grams of water was boiled to produce one serving of tea. In reality, many consumers may unnecessarily boil additional amounts, thereby increasing the amount of energy required to boil the water. This would result in additional impact at the consumption stage in both domestic and international scenarios. Thus, recommending that consumers to make a cup of tea by avoiding over boiling extraneous amounts of water, in fact, could have a meaningful contribution to mitigating tea’s environmental impacts.

International consumption can increase GWP and EP by 19% and 26%, respectively, which is largely attributable to the change of cooking energy from natural gases to an electric-gas mixed scheme.

Ökolog. Lebenszyklusanalyse

DOI: 10.3390/su11216042

In China, Yunnan is one of the earliest Provinces in which tea trees are planted. For example, Camellia sinensis var. assamica originated from southern Yunnan (including Xishuangbanna, Simao, Lincang, etc.). It is recorded in the ancient books that large-scale planting of this type of tea in these areas began in Tang Dynasty (800 years ago), so most ancient tea gardens in these areas had been existed for more than 800 years (Long et al. 1997a). At that time, these areas were mostly covered by forests, tea trees were planted by wiping off understory plants and keeping upper-layer trees. The ancient tea gardens discovered recently are covered by subtropical evergreen forest canopy. The planting pattern that tea trees are planted under natural forest is a kind of imitation to the natural ecosystem (Guo and Christine 1995; Guo et al. 1996). Local residents are used to keep some trees in tea gardens to creat shade to tea trees which are commonly thermophilic, hygrophilous and shade-tolerant plants. Thus the ecosystem of ancient tea garden comes into being. And the growing status of tea trees and output of tea products will peak at 80 % light intensity

endangered: d Carallia lanceaefolia, Toona ciliata for Timber and medicin; Cinnamomum mollifolium Spicery and timber Cyclobalanopsis rex, Magnolia henryi

The results showed: (1) Ancient tea garden communities have high biodiversity, whose plant species diversity (H = 3.03) is lower than that of secondary forestry (H = 4.59) and higher than that of normal tea garden (H = 2.62); (2) Life forms analysis of plant species showed the vertical structure of the ancient tea garden communities are intact, herbs, trees, shrubs, vines, epiphytes are included, which is similar to that of secondary forest, while normal tea garden is dominant by herbs and no trees; (3) A large number of protected species, including five endangered, seven vulnerable and three rare, is well conserved in the ancient tea garden, while no protected species were found in secondary forest and normal tea garden; (4) The analysis of agro-biodiversity revealed that 56 % of plant species in the ancient tea garden are effectively used by households, while no plant except tea trees is used in normal tea garden; (5) The integrated values of ancient tea garden and normal tea garden illustrated that both biodiversity conservation and economic income of ancient tea garden are higher than that of normal tea garden. We suggest that the local peoples’ knowledge and experience on resource management and utilization should be well documented and encouraged, and effective conservation and reasonable utilization of ancient tea garden would be achieved through training and demonstration with the participation of the local government, research institution and farmer.

Ökolog. Feldstudie

DOI: 10.1007/s10457-012-9567-8