Matcha is the oldest Japanese variety of tea, the tradition of drinking which came to us practically unchanged from the Song era.
The first spring flushes - buds and tender leaves - are taken as raw materials for matcha. Three weeks before picking, the tea bushes are shaded, limiting access to direct sunlight, in order to increase the content of the beneficial amino acid L-theanine.
Green tea contains four main catechins, namely epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG), of which the latter is the most active and abundant, and matcha is their best concentrated source.
With its unique chemical composition and prized flavor that sets it apart from other tea beverages, matcha is considered a tea of the highest quality. Its healing properties are explained by its high content of antioxidant and anti-inflammatory substances. Research confirming the high antioxidant potential of matcha tea states that this effect is due to its significant content of catechins, a type of phenolic compound that has beneficial effects on human health. Thanks to its ability to prevent many diseases and support cognitive function, regular consumption of matcha tea can have positive effects on both physical and mental health.
The purpose of this review was to gather information about the health benefits of matcha tea.
This is the first such review to systematically present the main bioactive compounds of matcha tea.
Introduction
In many countries, tea is one of the most consumed beverages, second only to water. Its distinct taste, aroma and health benefits are highly valued throughout the world, as are its socio-cultural connotations (traditions of society). Green tea is available in many varieties: loose leaves, tea bags, or powdered form.
Matcha is a powdered form of Japanese green tea (Camellia sinensis) of the Tencha variety. The popularity of the drink is growing all over the world. It is particularly rich in antioxidant compounds due to its special cultivation method. According to the traditional method, tea bushes are covered with bamboo mats during most of the growing period to protect the leaves from excessive exposure to direct sunlight. During this process, plants can produce greater amounts of amino acids and bioactive compounds, including chlorophyll and theanine, which are responsible for matcha's unique, non-bitter taste and distinctive bright color. As a result, matcha is highly prized for its quality and is considered the most flavorful green tea.
Chemical composition of Japanese matcha green tea
The health benefits of green tea come from the presence of natural antioxidants such as polyphenols, a wide range of compounds that make up up to 30% of green tea's dry weight. Polyphenols are considered exceptionally powerful antioxidants, comparable to the effects of vitamins such as vitamins C and E, carotene and tocopherol. The amount of health-promoting active ingredients contained in tea drinks depends on the type of tea, number of tea leaves per serving, temperature and brewing time.
Catechin content
Research confirming the high antioxidant potential of tea drinks states that it is due to the significant content of catechins, a type of phenolic compound that has beneficial effects on human health. Green tea contains four major catechins, namely epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG), of which the latter is the most active and predominant in percentage terms. High polyphenol content has greater free radical scavenging ability than even vitamin C! Phenolic compounds are naturally found in the leaves of Camellia sinensis. Thus, matcha can be characterized as the main source of catechins in the daily human diet.
Epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin are the main active catechol-type compounds and are therefore found in the largest amounts in plant foods. Catechins derived from tea exhibit outstanding antioxidant activity due to their ability to neutralize free radicals and enhance the detoxification activity of enzymes including glutathione peroxidase, catalase and glutathione reductase.
Grzesik et al reported that catechins have greater antioxidant capacity than glutathione, vitamin C, and flavonoids, suggesting their key role in maintaining cellular redox homeostasis.
According to a study by Koláčková et al., the total polyphenol content of matcha tea is in the range of 169–273 mg GAE/g. However, Nishitani and Sagesaka observed lower polyphenol content in matcha than in other greens.
It was then suggested that this result may be due to shading of tea plants, which inhibits the synthesis of polyphenols. However, the catechin content of green teas is much higher than that of black teas, ranging from 5.46–7.44 mg/g compared to 0–3.47 mg/g in black tea.
Caffeine content
Caffeine is an important component of tea drinks and is responsible for their characteristic and desirable taste. At the same time, it is a powerful antioxidant that increases the antioxidant potential of the drink. Its levels may be related to the time of harvest and the age of the leaves - the older the leaves, the lower the caffeine content. The caffeine content also depends on the type of tea, weather conditions during the growing season, and the brewing method. Caffeine's effects are rooted in its antioxidant potential, which neutralizes reactive oxygen species and increases the activity of antioxidant enzymes and overall glutathione levels. At normal doses, caffeine can reduce persistent oxidative stress, reducing the incidence of free radical-mediated diseases. In addition, caffeine can suppress the secretion of pro-inflammatory cytokines, demonstrating anti-inflammatory effects.
Matcha has a relatively high caffeine content compared to other green teas, which gives it a unique aroma and taste. The caffeine content of green tea was found to range from 11.3 to 24.67 mg/g, while that of matcha was found to range from 18.9 to 44.4 mg/g. In comparison, most coffee beans contain 10.0–12.0 mg of caffeine/g of coffee bean.
Phenolic acid content
Phenolic acids are secondary plant metabolites that have high antioxidant and anti-inflammatory potential, in addition to neuroprotective and hypoglycemic effects. They have also been reported to inhibit the growth of cancer cells and prevent metastasis. Some phenolic acids, by modulating lipid and carbohydrate metabolism, may support the regulation of metabolic disorders. One of the most common compounds in this group found in foods is chlorogenic acid.
A study by Koláčková et al found that the total content of phenolic compounds in alcoholic extracts reached 273 mg GAE/g. Detailed analysis revealed the following maximum levels of phenolic acids in matcha tea samples, varying according to various criteria, including origin: gallic acid - 423 µg/g, p-hydroxybenzoic acid - 243 µg/g, chlorogenic acid - 4800 µg/g, caffeic acid - 223 µg/g, ferulic acid - 289 µg/g and ellagic acid - 371 µg/g.
Contents routine
Rutin, a polyphenolic compound, is a powerful antioxidant. Its synergistic interaction with ascorbic acid may enhance the protective effects of both substances in the cardiovascular system by strengthening blood vessels. It also has anti-diabetic and anti-inflammatory properties, thus preventing pathologies associated with diabetes. Its antioxidant and anti-inflammatory effects offer potential for the prevention of conditions of free radical or inflammatory origin, including neurodegenerative conditions.
According to Jakubczyk et al., matcha green tea has exceptionally high rutin content compared to other teas available on the market. The authors compared the level of rutin found in matcha (1968.8 mg/L) with that in buckwheat (62.30 mg/100 g) (the latter recognized as one of the richest sources of rutin in the human diet) and demonstrated that matcha tea can be a better source of this compound than other foods. The findings of Jakubczyk et al seem to be consistent with the observations of Koláčková et al.
Quercetin content
Quercetin is a phytochemical with antioxidant and neuroprotective activities. In addition, normalization of carbohydrate metabolism was observed due to inhibition of glucose absorption from the gastrointestinal tract, regulation of insulin secretion and improvement of insulin sensitivity in tissues. Moreover, the combination of quercetin with epigallocatechin gallate (EGCG) may enhance the anticarcinogenic effects of both.
The quercetin content of matcha aqueous extract was measured at 1.2 mg/ml by Schröder et al., which is slightly higher than that of traditional green tea (1.1 mg/ml). On the other hand, Koláčková et al determined that the level of quercetin in alcoholic extracts reached 17.2 μg/g.
Vitamin C content
Vitamin C is a powerful exogenous antioxidant. Thanks to its properties, it strengthens the body's immune defense. This is an important micronutrient in human nutrition that must be obtained daily in sufficient quantities.
Jakubczyk et al showed that matcha tea infusions contained between 32.12 and 44.8 mg/L of vitamin C, depending on the temperature of the water used to prepare the infusion and the type of tea. A study by Koláčková et al found that matcha contains more than twice as much vitamin C than other green teas. Its content was determined to be in the range of 1.63–3.98 mg/g, depending on the type of product and its origin.
Chlorophyll content
Thanks to being grown in the shade, matcha tea has a high chlorophyll content, which provides its unique vibrant color. Chlorophyll and its derivatives have strong antioxidant and anti-inflammatory activity.
Levels of bioactive compounds, including chlorophyll, in Tencha-type tea leaves used specifically for matcha were determined by Ku et al. The chlorophyll levels in Tencha type leaves were higher than those in traditional green tea, being 5.65 mg/g and 4.33 mg/g, respectively.
Theanine content
Theanine is an amino acid found in the tea plant Camellia sinensis. Because the plants used to produce matcha are grown in the shade, the theanine is not destroyed. As a result, Tencha leaves contain more of it than other teas. The relatively high theanine content of matcha tea is responsible for its unique non-bitter taste, and when combined with caffeine, provides the flavor sensation and umami characteristic of this type of tea. The combination of l-theanine and caffeine may increase concentration, alertness, and efficiency more than using either compound alone, further reducing stress.
Kaneko et al found l-theanine in matcha tea infusions to be 6.1 mg/L, while Unno et al found 44.65 mg/g of this compound in matcha tea samples.
A summary of the health benefits of the main bioactive compounds in matcha green tea is presented in Figure 1.
Figure 1. Health benefits of the main bioactive compounds of matcha green tea.
Parameters affecting chemical composition
One of the parameters that has a significant impact on the chemical composition and health benefits of the tea drink is the temperature of the water used to prepare the infusion. This is due to the extraction of bioactive compounds and the higher kinetic energy of tea brewed at high temperatures.
The distinctly high antioxidant potential of matcha tea can also be attributed to the grinding process and ultimately the powdered form.
Fujioka et al demonstrated that infusions prepared by steeping tea leaves had lower polyphenol content than infusions prepared from the powder form. Thus, the grinding process itself can speed up the recovery of polyphenolic compounds. Shishikura and Khokhar observed (taking into account the average time required to prepare the tea) that its powdered version is more effective and active in terms of extraction in a relatively shorter time (1 min), and therefore seems to be a better choice.
Komes et al studied 11 green teas that varied in production method and form, including bagged, loose and powdered. Matcha tea was brewed at three temperatures (60, 80 and 100°C) for different durations (3, 5, 10, 15 and 30 minutes). The scientists measured the effects of leaf fragmentation, product form, brewing time and temperature on phenolic content and antioxidant capacity determined using various methods (DPPH, FRAP and ABTS). In all green teas, antioxidant capacity increased with the temperature of the water used to prepare the infusion, and optimal values were observed at the highest temperature with a 3-minute steeping time. It was concluded that the antioxidant potential of green tea increases in proportion to its phenolic content. Additionally, the powder form had the highest parameters of all green teas and the required extraction time was the shortest. Increasing the cooking time of matcha tea powder did not increase its antioxidant capacity.
The content of health promoting substances, including polyphenols, is also influenced by agro-climatic conditions during the growth of the tea bush, such as the number and distribution of sunny and rainy days, fertilization and plant protection measures, if any, etc.
Health Promoting Properties
Anti-carcinogenic effects
The anti-carcinogenic properties of green tea and its key ingredient, epigallocatechin gallate (EGCG), have been extensively studied by scientists from around the world. The mechanisms of EGCG's anticancer effects may be related to inhibition of tumor angiogenesis, antioxidant effects, and suppression of inflammatory processes that promote transformation, hyperproliferation (increased proliferation of cells by division), and initiation of carcinogenesis.
The pathogenesis and progression of colorectal cancer is greatly influenced by a healthy diet and lifestyle. Obesity, especially the visceral type, as a consequence of a long-term unhealthy lifestyle, increases the risk of developing gastrointestinal cancer. Consuming pain
Large amounts of EGCG may help reduce the incidence of colorectal cancer, in part due to inhibition of tumor growth factors. Moreover, EGCG is able to inhibit the growth and cause apoptosis (self-destruction) of cancer cells. Increasing tissue sensitivity to insulin and leptin and reducing blood lipid parameters may suppress obesity-associated carcinogenesis. Supplementation of green tea extracts can further prevent recurrent adenomas, which in most cases can develop into colorectal cancer. Research findings regarding EGCG supplementation also include inhibition of the growth and proliferation of gallbladder and bile duct cancer cells, as well as a reduction in the risk of bile duct cancer.
Catechins act synergistically with anticancer drugs (that is, they enhance each other's effect) and can be used for supportive (complementary) cancer therapy, as well as for cancer prevention. Vitamin C has also been linked to protective effects against cancer.
Anti-inflammatory effects
The inflammatory response is an integral part of many diseases. This can lead to the production of excessive amounts of substances that promote the production of reactive oxygen species (ROS), which can damage cellular structures and lead to long-term disruption of overall body function and signaling, promoting inflammation. The main effect of anti-inflammatory and antioxidant substances is to suppress inflammatory signaling by scavenging ROS.
Supplementation with EGCG, the main bioactive component of green tea, may alleviate inflammatory complications following the use of cardiopulmonary bypass for major cardiac surgery, including lung injury and dysfunction.
By regulating the inflammatory state, EGCG also helps reduce the susceptibility to gallstone formation.
Hypertension is controlled by multiple genes, with inflammation and vascular remodeling implicated in the pathogenesis of this condition.
Drinking green tea drinks, which are high in bioactive compounds that regulate inflammation, slows the progression of hepatitis by suppressing the expression of inflammatory cytokine genes and proteins.
Cardioprotective effects
Cigarette smoking is recognized as one of the main risk factors for cardiovascular diseases. In an animal experiment, rats were exposed to cigarette smoke with simultaneous oral administration of EGCG. Markers of myocardial damage and lipid abnormalities increased with smoking exposure. The introduction of EGCG reversed these aberrations. The results of this study suggest that the antioxidant EGCG may have a protective effect on cardiac muscle by preventing cardiac inflammatory changes by reducing oxidative stress. EGCG may potentially exert a protective effect on cardiac muscle in surgical patients who are susceptible to ischemic injury by inhibiting the activation of stress-activated protein kinase and signaling pathways that promote the inflammatory response.
Antiviral properties
The immunomodulatory properties of green tea and its antiviral effect may help prevent and regulate the immune response in infectious diseases, including COVID-19. There are many studies on the antiviral properties of green tea, but they are mostly based on reports of traditional green tea. The mechanism of action and specific properties of matcha green tea are still unknown and are equivalent to the general reports of green tea, despite the different composition and ratio of bioactive compounds.
However, in one of the few studies, Ohgitani et al demonstrated that matcha green tea may have antiviral activity (by inactivating SARS-CoV-2), which is promising but requires more detailed studies. The documented potential properties and probable mechanism of action of green tea compounds are presented in Table 1 with reference to the original scientific papers (see original article).
Conclusions
Japanese matcha green tea powder contains a large number of substances with antioxidant and anti-inflammatory effects. It has promising potential health benefits mainly due to its high concentration of catechins. When consumed regularly, it can support the body's efforts to maintain health and prevent disease.
Research into the effects of drinking matcha tea and its individual components on specific diseases is still relevant and necessary. The current level of knowledge only covers some of the health benefits of this tea. To confirm the validity of recommendations to increase the consumption of matcha tea drinks, it is necessary to conduct a deeper and broader analysis of its effects on the human body.
Full
original text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7796401/
Department of Human Nutrition and Metabolomics, Pomeranian Medical University, Szczecin, Poland
