GREEN TEA & HEALTH
Health Benefits of Green Tea-Prologue
As mentioned in the section History of Tea (see About Japanese Tea), tea was first used for its medicinal properties. In the 13th Century, the Buddhist Monk Eisai stressed the beneficial effects of tea in his book Maintaining Health by Drinking Tea. He said "Tea is a miraculous medicine for the maintenance of health. Tea has an extraordinary power to prolong life." Eight hundred years ago it must have seemed miraculous but the fact is tea contains a number of substances that have been proven to be beneficial to our health.
Some of the components of green tea and their health benefits are shown below:
|Component of Green Tea||Health Benefit|
Lowers blood cholesterol
Inhibits increases of blood sugar
Promotes better vision
|Vitamin C||Fights colds and flu
|Flavonoids||Strengthens blood vessel walls
Improve the health of the heart
Reduces symptoms of menopause
Acts as diuretic
Although we don't yet know all the health benefits of tea, here are several facts and studies that point to it being a very good drink.
A key health benefit of tea is its power as an antioxidant. Simply put an antioxidant is a substance that fights or blocks the oxidation process that is occurring within us. Our body consists of 6 trillion cells and each cell is covered by an unsaturated fatty acid in the form of oil that protects the cell. Over time the oil becomes oxidized and it can no longer protect the cell adequately. The oxidation is caused by a substance called active oxygen which is in the air we breathe and is also produced when the body's cells burn oxygen. There are several types of active oxygen and the most aggressive one is called a Free Radical. Free radicals are powerful oxidizers and unfortunately 2% of every breath is made up of free radicals. They cause 100 thousand cells in your body to be oxidized everyday. Further, smoking, stress, alcohol and an intemperate lifestyle will accelerate the effect of active oxygen.
The oxidation of our cells has numerous effects. One of the most noticeable is the aging process, which is accelerated by the destruction of the cell structure by active oxygen. Recent studies indicate that active oxygen can lead to other serious illnesses such as:
- Arteriosclerosis which can be caused by active oxygen oxidizing LDL, the bad cholesterol.
- Diabetes which can be caused by an unbalance in a hormone destroyed by active oxygen.
- Active oxygen has the power to rewrite the DNA of a cell or harm it in other ways it. This can produce a mutation of the cell leading to cancer.
Now, how can we mitigate the impact of active oxygen? There are substances called scavengers that work in our body to remove active oxygen. There two types of scavengers: the first is an enzyme that is produced automatically in our body and the second is any antioxidant substance that we consume.
The first scavenger is called SOD (Super Oxide Dismutase). SOD is produced in each internal organ and fights active oxygen. This enzyme is a compound of protein and minerals. Consuming foods such as beans, milk, eggs and tofu improve the ability of the organs to produce SOD. But this enzyme cannot remove all of the active oxygen and, as we age, the amount of SOD produced decreases. So increasing our intake of food high in antioxidants becomes important.
The antioxidant substances that most people are aware of now are polyphenols including catechins, vitamin A (beta carotene), vitamin C, and vitamin E. Some studies indicate that the catechin antioxidants are even stronger than the vitamins, and we can agree because of the way catechin fights the active oxygen. Our body consists of a fatty part of the cells and aqueous part between each cell. Vitamin C works only in the aqueous part and beta carotene and Vitamin E work only inside a cell with the fatty part. Catechin works on the film of the cell and its power is efficacious in both the fatty and aqueous areas. Increasing our intake of the foods high in any antioxidant helps our body to remove active oxygen and free radicals before they can do any damage.
Now you know that green tea is a great source of antioxidants because it contains many antioxidant substances such as vitamin A, C and E and the powerful catechin antioxidant. It's no wonder that green tea, with so many antioxidants, is considered a health food. Although many of the other health benefits of tea are familiar because the same vitamins (Vitamin C for example) and enzymes in green tea occur in other healthy foods (fruits and vegetables), a key difference is that green tea can be easily consumed several times a day everyday.
"Can tea reduce one's weight?" Our answer is a definite "Yes and No!" We all know there is only one possible way to lose weight. Only when the energy used is greater than the energy consumed will someone lose weight. This means that unless you reduce your intake of calories, you need to exercise more. Natural green tea itself will not cause you to lose weight like some dietary supplements claim. However tea still has a benefit in a weight loss program and green tea can have an impact on both the energy expenditure and energy intake side of the equation.
Some experiments show that catechin in green tea raises metabolic rates and speeds up fat oxidation resulting in a higher expenditure of energy. In other words, drinking green tea before and/or shortly after exercise can be very effective in increasing your expenditure of energy. On the energy intake side, catechin controls the assimilation of excessive cholesterol or fat into the bowel. One experiment in Japan indicated that this assimilation works even better with a combination of caffeine, catechin and L-Theanine (amino acid), three major components of green tea, rather than any of these by themselves.
Now what about the people who claim they lost weight by just drinking green tea? In our opinion, a person would easily lose weight with green tea if they substituted it for all the artificial, chemical laden, and heavily sweetened beverages that they drink now. If you are a tea or coffee (black, no sugar or milk) drinker already and switch to green tea, we don't think you would lose weight just by switching.
Tea is also good as an anti-bacterial agent. For example, it's customary to drink green tea with sushi in Japan. It is very effective in preventing food poisoning from some raw fish. Studies also indicate that catechins and the theaflavins of black tea are very effective in slowing the spread of bacteria such as botulinus. This same anti-bacterial attribute may also be effective in preventing cavities from forming in teeth. Here is another example: Bedridden patients often suffer from bedsores or pressure-sores in the hospital. One hospital in Japan experimented with treating the sores with green tea liquid. They found that the sores healed faster than if a chemical disinfectant was used.
Green tea is considered effective in preventing the flu because of the anti-virus agents in green tea. A virus can’t live by itself and must infect a host like a human being for its continued existence. Once in the host, the virus uses protuberances much like shoe spikes to stick the host's mucous membrane where it receives nutrition and grows. According to the study in Japan, the catechins, a component in green tea could attach to virus spikes which would prevent the virus from attaching to the host cell.
There is also some new information from a study in Japan. The study was conducted by Professor Hiroshi Yamada of Shizuoka Prefecture University and reported by Dr. Isao Tomita, Doctor of Pharmacy, a professor emeritus at Shizuoka Prefecture University and advisor at Shizuoka industrial University, Ocha Department. The study was conducted in a senior nursing home where some of the residents gargled with EGCG (Epigallocatechin Gallate) in a water solution over a period of 30 days. The results of the study indicate that there was significantly less influenza infections in the group that gargled with the EGCG solution.
The EGCG mentioned above is one of the catechins in green tea. While there are three other beneficial catechins in green tea, EGCG is the most powerful. EGCG as an antioxidant is about 25-100 times more potent than vitamins C and E.
Also, several elementary schools in Shizuoka Prefecture started a project where all the students gargle with green tea on a daily basis in winter. These schools had a lower rate of absenteeism than schools where the students did not gargle.
While this is exciting information, it is a recent study and more analysis is needed to draw specific conclusions. Also please do not rely on only one item to prevent the flu. Follow the recommendations of the medical community; wash your hands frequently, eat healthy, exercise, and get plenty of sleep. If you would like to use green tea in you flu prevention plan, here are two suggestions:
1. Bancha: Bancha has the most EGCG of the green teas. Brew it with boiled water and brew longer than for a normal cup (more than 2 minutes). This will make a strong cup of tea with plenty of catechins. You can either enjoy this strong cup of tea at teatime or cool the tea and gargle with it. (Gargling for viral prevention is practiced more in Japan than in North America.)
2. Powdered Sencha: Our Powdered Sencha is produced from quality Sencha and is a well balanced healthy drink with lots of catechins. Powdered tea has the advantage of being quick and easy to make anywhere. Just pour 1/8 teaspoon into 5oz or less cold water and mix well. It's so easy you can enjoy an extra cup or two at work, at school, or at home.
There is research that suggests green tea catechins, especially EGCG (Epigallocatechin Gallate) can help improve your natural immunity if you consume an adequate amount of tea over a long period. The good thing about green tea is that it is a tasty drink so it is easy to drink it on a daily basis.
L-Theanine is a unique amino acid found especially in high quality green tea and very few other sources. While L-Theanine is known for increasing the taste of Umami, a sweet full-bodied flavor, L-Theanine is also known for its benefits as a relaxant. It generates alpha-waves in the brain. Alpha waves are emitted when the brain is in a relaxed state. Scientists are also examining L-Theanine’s ability to improve the brain’s memory capability.
L-Theanine has other benefits as demonstrated in an experiment using L-Theanine at a company in the United States. The volunteers were 87 females between the ages of 35 and 60 with symptoms of a menopausal disorder. Among the ladies in the group who took an extraction of L-theanine, there were emotional and physical improvements with reductions in swelling and headaches. L-Theanine also suppresses the stimulant function of caffeine and this is why high quality green tea makes you relax even though the tea contains caffeine.
There are several reasons why L-Theanine is only found in specific teas such as Gyokuro, Matcha, Sencha and Kukicha. L-Theanine can only stay in the leaf while it is in the shade or in sunlight for shorter periods. L-Theanine will turn to tannin under full sunlight. The shading process used for Tencha and Gyokuro reduces photosynthesis resulting in increasing L-Theanine. Higher quality Tencha and Gyokuro is grown with a longer shading process, thus higher grade tea tends to contain more L-Theanine as you see in the chart below.
The new buds and leaves of higher quality Sencha are picked early once they are flushed and spend less time under sunshine compared with middle or lower grade Senchas. Bancha contains very little or no L-Theanine because it is grown under sunshine for longer time than Sencha. The stem part of Kukicha is considered to contain more L-Theanine than the leaf part, because the stems are not affected by photosynthesis. Therefore green Kukicha may contain more L-Theanine than Sencha and Karigane (Gyokuro Kukicha) may contain more than Gyokuro depending on the grade of Kukicha.
|Type of tea||Theanine (mg/100g)|
|Type of tea||Higher-grade||2,260|
Source: The Science of Tea (Cha no Kagaku), Keiichiro Muramatsu (ed.).
Tea has been part of Japanese culture for many centuries. As mentioned above, the early use of tea was for medicinal purposes and many health benefits of green tea have been proven during the years. Since tea has been around for so long, people have found other uses for this wonderful plant. Here are several:
- Use it as a deodorizer
Green tea leaves have traditionally been used to naturally absorb odors. You can place tea leaves in a bowl to absorb unpleasant odors in a room, leave some in the refrigerator in place of baking soda, or make a sachet with green tea and place in a drawer.
- Use it to soothe your skin
Green tea can help relieve sunburn and ease minor skin irritations. You can use a spray bottle to mist prepared green tea on sunburned areas or make a compress soaked in green tea and apply to irritated areas. Since it's an all natural treatment, you can apply it several times a day.
- Tea is good for the feet
Try soaking tired feet in green tea to prevent unpleasant fungal infections. You can also apply used tea bags as compresses on specific infected areas.
- It can soothe the eyes
Soak cotton pads in green tea and place them over eyes for 10 minutes to reduce the puffiness of tired eyes. You'll look revitalized and refreshed.
- Tea is good for teeth and bones
Green tea contains fluoride, making it a superstar for keeping gums and teeth healthy. It is also naturally high in minerals and aids in strong bone density.
- Tea can soothe sore throats
The anti-viral effect of green tea make it an excellent remedy to help ease the symptoms of a cold or flu. You can also gargle with green tea to soothe a sore throat and prevent bad breath.
- Use green tea in a facial mask
A green tea face mask is good for normal and oily skin. It will smooth, moisturize, soften, and tighten your skin, and the antioxidants in the green tea will protect your skin from sun damage. It's simple to make a green tea face mask and the instructions are on several beauty related websites.
Houjicha is interesting in that it has one ingredient that the other non-roasted teas don't have. The roasting process used in manufacturing Houjicha produces "Pyrazine". Pyrazine is an aromatic organic compound with some special benefits. Pyrazine is known to improve blood flow within a blood vessel and overall blood circulation in the body. This could help prevent the formation of blood clots. Additionally, the improved circulation gets blood to more parts of the body thus warming you from the inside. There is more work to be done in this area but it looks very promising. With Houjicha you would also benefit from its relaxing aroma.
In addition to the benefits of Pryazine, Houjicha contains less caffeine than any other Japanese green tea. If you are a coffee or black tea drinker and want to reduce your daily intake of caffeine but still want good flavor, Houjicha may be the best substitute. In general, Houjicha is similar to coffee or black tea with a robust flavor, hearty aroma, and a dark color. Unlike coffee, Houjicha is still a green tea and has all the health benefits of green tea.
Fukamushi Sencha became very popular in Japan because of a program on Japan's sole public broadcaster, NHK TV.
The program focused on the city of Kakegawa in Shizuoka prefecture. Its population has the lowest death rate from cancer, and 20% lower medical expenses in all Japanese cities with a population over 100,000. It happens that Kakegawa is famous for the production of Fukamushi Sencha and many people there drink a lot of it all day long. They also consume the tea sediment in the cup. Fukamushi is made with an extra steaming process which causes the final product to be quite fine. The fineness of the tea leaves causes more of the leaves to be poured into the cup. Consequently the drinker not only benefits from the liquid but also from the nutrient rich parts of the tea leaves.
When we looked at the ranking of death rates from cancer in cities with populations over 100,000, we found that 7 of the 15 cities with the lowest rates are also tea production centers. Additionally, most of them produce a "casual" grade Sencha. The casual grade Sencha is usually grown with lots of sunshine in order to maximize production. The sunshine produces more antioxidants (catechins) in the tea leaves than in premium teas. (Premium teas, such as Gyokuro, are shaded for several weeks before harvest to reduce its bitterness.)
According to Dr. Samejima at Kakegawa City Hospital, Kakegawa's also has a 30% lower rate of citizens who are suffering from the heart disease and cerebral infarction compared with other cities in Shizuoka prefecture. This low rate of diseases eventually leads to lower medical bills since the population avoids long term illnesses.
People in Kakegawa drink many cups of Fukamushi Sencha a day and they seem to be benefiting from it. The extra steaming process used in making Fukamushi causes the ingredients to be extracted quickly and likely to a greater extent than a regular Sencha. Further, Fukamushi Sencha produced in these areas contains more catechin because of growth with full sunshine. More catechin means more tannin causing bitterness, but the deep (longer) steaming process suppresses the bitterness. So if you are looking for a healthy, mild cup of tea try Fukamushi Sencha.
Bancha contains more of a unique ingredient than any other Japanese green tea called Polysaccharide. Polysaccharide restrains enzymes (i.e. amylase, sucrase) from metabolizing the saccharide (i.e. sugar) and eventually may prevent body from absorbing the saccharide or sugar. This makes Bancha the perfect iced tea for a summer cookout since more polysaccharides are extracted with cold brewing than with hot brewing. This information may be new to North American tea consumers, but is quite well known in Japan, and some cold brewed Bancha products are found in health stores in Japan.
The definition of "health" from the World Health Organization is "health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." As we all know, there are many people who are physically healthy but have problems socially or mentally. In today's world, where we have great medicines that help keep us physically healthy, it is still difficult to acquire mental or social health through the use of medicine. A tea break can be part of the cure for social ills and we are personally hoping that tea will be found to have more mental health benefits than just physical.
There are many more claims about the health benefits of tea. Some of these are yet to be proven by scientific study but the current level of knowledge certainly shows that tea is "good food". A key point, however, is that tea is just one part of a healthy life style. One cup of tea a day won't suddenly make a person healthy, but there could be a major benefit if tea was substituted for all the artificial, chemical laden beverages that people drink. And the best thing about tea is it tastes good. Drinking several delicious cups of tea during the day and with meals may keep you healthier than any medicine. That is the reason why people have loved tea for 5000 years.