About Health Benefits
We will introduce three health ingredients that represent Japanese tea.
Catechin is classified as a furanovoid among many polyphenols. It is the main astringent component of Japanese tea, and is present in all Japanese teas, from bancha to houjicha. There are four types of catechins in tea leaves.
The catechin content of dried tea leaves is around 15%, which varies depending on the time of picking, cultivation conditions and varieties. Ichibancha has less catechins, and second and third teas have more catechins. This is because catechin production increases in proportion to the amount of sunlight. Also, in the case of matcha, etc., the catechin content is reduced by covering cultivation for about two weeks before the plucking season to block the light.
When arranging the four types of catechins in descending order,
1. Epigallocatechin Gallate (EGCG) 59.1%
2. Epigallocatechin (EGC) 19.2%
3. Epicatechin gallate (EGC) 13.7%
4. Epicatechin (EC) 6.4%
(Source) Functions of Tea - New Possibilities of Biological Functions; Edited by Keiichiro Muramatsu (Representative) (Gakkai Publishing Center Co., Ltd.)
EGCG, in particular, has a wide range of physiological activities, including antioxidant activity. Of these, epicatechin is contained in polyphenols other than tea, such as apples and chocolate, but the other three types are catechins unique to tea.
Also, heat treatment to stop oxidative fermentation changes the shape of each, so there are 8 types of catechins.
In the case of oolong tea and black tea, oxidative fermentation is performed, so catechins change to oxidative polymers such as theaflavin. This is a component of fragrance, and colorless catechin changes to red, giving it the unique aroma and color of oolong tea and black tea, but the amount of catechin that remains without oxidation decreases.
The effects of catechins have been reported as follows.
- Lipolysis effect
- Other effects (cancer prevention)
More than half of the amino acids in tea are theanine, and the rest are glutamic acid, aspartic acid, arginine, and serine. Theanine is an amino acid unique to tea that is produced near the base of the tea tree and used for the growth of tea leaves through the trunk and branches. Young buds in the early stage of bancha are the most abundant, followed by first bancha, then second buds, and mature buds that have finished growing are extremely reduced. Therefore, unlike catechin, which is a bitter component common to all Japanese teas, the higher the quality of Japanese tea, the more theanine it contains. Theanine content varies depending on these conditions, but is generally around 6-20mg per gram of tea.
Tea leaves cultivated in high altitude mountains, where the temperature difference between day and night is larger than in lowlands, tends to be colder at night, so theanine is not consumed and the umami-tasting theanine tends to be stronger. Also, like gyokuro and matcha, covering cultivation two weeks before the picking season prevents amino acids from changing to catechins, leaving the umami-tasting theanine in the tea leaves.
Theanine is the umami component of tea, and the higher the content, the more expensive it is. Since ancient times, the Japanese have regarded tea with a high umami component as a luxury tea, and recent research has proved its high efficacy.
In order of the abundance of theanine, first-grade tea from high altitude areas (our Matcha Tenku series), first-grade tea from high-altitude areas (our Mino Shirakawa Sencha), gyokuro and matcha grown in cover cultivation in lowlands, and green tea grown in lowlands. 1st tea, 2nd tea in high altitude areas, 2nd tea in lowlands, 3rd tea and later, Hojicha, black tea, and Chinese tea. This is because black tea and Chinese tea are mainly composed of catechins, which oxidize and change into fragrant ingredients, and Chinese tea is roasted at high temperature, so proteins are decomposed. In addition, the state of amino acids such as theanine differs depending on what kind of tea leaves are used in the original roasted tea leaves, the setting of the roasting temperature, and the method of roasting. Also available (see our Hoji Matcha Tenku description).
The effects of theanine have been reported as follows.
- Protects nerve cells in the brain and reduces stress and anxiety
- Improving autoimmunity and cognitive function
- Increase in serotonin, which is called the happiness hormone
Pyrazine is the aromatic component contained in high-quality hojicha. During the roasting process, amino acids are converted into pyrazine, a fragrant component. Cheap roasted green tea does not produce pyrazine because it contains less amino acids. This aroma component contributes to the pleasant aroma of foods such as roasted green tea, coffee, bonito flakes, chocolate, and grilled meat.
Pyrazine dilates blood vessels and improves blood circulation.
By the way, it is known that tartary buckwheat tea improves blood fluidity. It was thought to be due to the antioxidant action of rutin, but this alone could not explain the effect. However, a 2006 research report by the Nagano Prefectural Industrial Technology Center announced that alkylpyrazines produced during the manufacturing process of buckwheat tea greatly contribute to improving blood flow.
We will introduce the materials that serve as the basis for the efficacy of health ingredients. Research on all of these ingredients has been accumulating in recent years, but among them, we have selected those with high evidence such as systematic reviews, meta-analyses, and peer-reviewed articles.
Reduces total cholesterol and LDL (low density riboprotein) cholesterol. LDL cholesterol plays a role in transporting cholesterol made in the liver to the whole body.
A systematic review and meta-analysis published in the Journal of the AMERICAN DIETETIC ASSOCIATION in 2011 found that consumption of green tea catechins at doses ranging from 145 to 3,000 mg/day for 3 to 24 weeks significantly reduced total cholesterol, and decreased LDL cholesterol.
(Source: DOI: 10.1016/j.jada.2011.08.009)
Antioxidant activity and reduction of oxidative stress
Oxidation of the body is said to be a major factor in accelerating aging, and free radicals and active oxygen are greatly involved in the oxidation of the body. Not all of the oxygen taken in can be consumed, and 2-3% of the oxygen remains in the body as excess and changes into free radicals and active oxygen. The state in which these occur in the body is called "bodily oxidation". "Body oxidation" not only promotes aging symptoms, but also causes lifestyle-related diseases such as cancer, diabetes, dyslipidemia, and arteriosclerosis.
A systematic review published in Nutrition Research in October 2021 confirmed that regular drinking of green tea boosts antioxidant status and reduces exercise-induced oxidative stress. This is in the dose range of 400-800mg of catechins per day when green tea is consumed for at least one week before exercise.
However, the European Food Safety Authority points out that taking EGCG in dietary supplements in excess of 800mh/day can have adverse effects on the liver.
(Source: DOI: 10.1016/j.nutrea.2021.08.004)
Other effects (cancer prevention)
The Saitama Cancer Center of Japan has announced research results that catechins have the potential to prevent cancer. "Biophysical Approach to Mechanisms of Cancer Prevention and Treatment with Green Tea Catechins"
(Source: Paper DOI: 10.3390/molecules21111566)
Although this is not a systematic review that systematically analyzes multiple similar studies and removes bias, it recommends 10 cups of green tea per day, equivalent to 2.5 g of green tea extract, which is essential for health increase. And other cancer prevention studies have been published. It is hoped that research in this area will advance.
Protects nerve cells in the brain and reduces stress and anxiety
According to a systematic review “The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review” published in the academic publication Springer Nature in November 2019, 1 day Supplementing with 200-400mg of Theanine has resulted in significant reductions in stress and anxiety in people in severe stressful situations. This is thought to exhibit beneficial properties via increased alpha wave production and decreased glutamate in the brain.
(Source: DOI: 10.1007/s11130-019-00771-5)
Increased levels of serotonin, the happiness hormone
L-Theanine ( N -ethyl-L-glutamine) or Theanine is the main amino acid unique to green tea. L-theanine has historically been reported as a relaxant, prompting scientific research into its pharmacology. It has been suggested to have micromolar affinities for AMPA, kainate, and NMDA receptors. In addition, it has been shown to exert neuroprotective effects in animal models, possibly through antagonism at group 1 metabotropic glutamate receptors. Behavioral studies in animals suggest improvements in learning and memory. Overall, L-theanine exhibits neuropharmacology suggestive of a potential neuroprotective and cognition-enhancing agent, requiring further investigation in animals and humans.
(Source: DOI: 10.1080/J157v06n02_02)
Improving autoimmunity and cognitive function
A paper published in May 2016 in the international peer-reviewed journal Beverages summarizes that theanine administration can improve the body's immune system. They also show that theanine is a promising derivative to modulate immune function by interacting with cysteine, an amino acid found in foods such as onions and garlic. In terms of cognitive function, the combined intake of theanine and caffeine has been shown to significantly improve cognitive ability in arithmetic, sentence verification, and overall attention, and has also been reported to improve cognitive ability and attention.
(Source: DOI: 10.3390/beverages2020013)
Pyrazine activates vascular endothelial relaxation factor and induces vasodilation.
It also induces vasodilation by inducing the release of nitric oxide and increasing peripheral blood flow. However, this study was a rat study, and further studies are needed to confirm the effects on humans.
(Source: Paper DOI: 10.1248/bpb.b17-00551)
Effect of pyrazine contained in barley tea to improve blood circulation
A Japanese beverage research institute has announced that when pyrazine contained in barley tea is ingested, blood transit time is significantly shortened and blood fluidity is affected.
(Source: Paper DOI: 10.3177/jnsv.48.165)
The health effects of Japanese tea published here refer to academic papers with highly reliable evidence. However, unlike pharmaceuticals, it is not something that has been approved by the pharmaceutical authorities of each country after sufficient clinical trials on humans and is administered based on a doctor's prescription. In addition, it is not possible to demonstrate therapeutic or preventive effects based on dosage and administration. In addition, it has not been approved by the Consumer Affairs Agency (or similar organizations in each country) as a specified health food that is expected to have specific functional enhancement effects.
Japanese tea is nothing more than a processed food made from agricultural tea leaves. Similar to vegetables and seafood containing various nutrients, its unique and high health effects are recognized as indicated above in the published academic papers, but if the main purpose is to treat, prevent, or improve the body, We recommend that you consult your family doctor.