Tea is widely regarded to be one of the most consumed beverages in the world. Green tea, native to China and Japan, has been drinking for centuries and still remains everyday drink and an important part of food culture and old traditions. In China, where green tea has a history dating back 2,500 years, this beverage was considered a treatment for numbers of health issues as well as for diseases prevention to promote longevity and healthy life.
In Japan, this divine beverage was discovered in 805 A.C. when Buddhist monks brought young tea trees from China. Known as the Way of the Tea, the Japanese tea ceremony is the aesthetic and spiritual performance with choreographic movements that features serving and drinking of a powdered Japanese Matcha.
The British, Russians, Indians consume a large amount of tea throughout of day, and each of those countries has its own unique recipes of tea brewing and serving.
According to many researchers, green tea is one of the healthiest and beneficial beverages. So, what's the biggest green tea benefits - this less processed and unoxidized variant of tea?
All major varieties of tea are typically brewed from the top leaves of the Camellia sinensis bush. The fresh leaves contain powerful antioxidants catechins including epigallocatechin-3-gallate (EGCG), an enzyme polyphenol oxidase, caffeine, amino-acid L-theanine, folate, choline, riboflavin, minerals zinc, calcium, manganese, magnesium, phosphorus, potassium, sodium, and fluoride.
The level of oxidation of the leaves actually determines the type of tea. Green tea is made of unfermented leaves and this is one of the least processed variants of tea that means all beneficial tea ingredients are still in the product.
Nutritional Value of Green Tea
Before revealing the primary green tea benefits for health, let's now explore its nutritional value. Unsweetened and unprocessed brewed green tea has absolutely zero calories. Plus, it contains a relatively lesser amount of caffeine, compared to black tea and coffee. For example, approximately from 20 to 50 mg of caffeine can be found in an 8-oz of green tea serving, compared with 115 to 170 mg of caffeine in the same amount of brewed coffee.
Furthermore, it contains antioxidants, polyphenols, and catechins. Natural chemicals, such as polyphenols offers anti-inflammatory and anti-carcinogenic health benefits.
A type of polyphenols catechins (epigallocatechin-3-gallate, epicatechin, epigallocatechin, epicatechin gallate), natural antioxidants, fighting with free radicals that cause cellular damage. Antioxidant properties are associated with cancer, cardiovascular and neurodegenerative diseases prevention. Catechins help to reduce blood cholesterol and high blood pressure, boost metabolism, and have an antibacterial effect.
L-Theanine reduces the perception of stress, promotes a relaxation effect, reduces high blood pressure, and improves memory and learning ability.
A type of polyphenols tannin provides bitterness when the tea is brewed a few minutes longer than recommended. Tannin is associated with anti-inflammatory and anti-carcinogenic effects and considered to interfere with non-heme iron absorption.
Caffeine takes effect as a stimulant for a central nervous system. L-theanine acts to limit the negative aspects of caffeine like anxiety, blood pressure increase, and insomnia while improving upon the positive effects such as the ability to enhance attention, concentration, alertness, and physical performance improvement.
To know more details about proven green tea benefits, please take a quick look at the following sections.
Green Tea Benefits
| Cancer Prevention
National Cancer Institute has declared that polyphenols (found in green tea) can decrease tumor growth and protect cell damage that's caused by ultraviolet UVB radiation. Studies have also proved that green tea can bring positive impacts for fighting the following types of cancer, such as breast, bladder, lung, prostate, esophageal (throat), colorectal (bowel), ovarian, stomach, oral, and skin.
According to the Italian study, among "randomized 60 volunteers with high-grade prostate intraepithelial neoplasia in a double-blind placebo-controlled study in which patients were randomized to 600 mg green tea catechins per day or placebo. After 1 year, only one tumor was diagnosed among the 30 men treated with green tea catechins, compared with nine cancers in the 30 placebo-treated men".
| Cardiovascular Health
Consumption of green tea can be associated with reduced mortality (including reduced risks of suffering from cardiovascular diseases). This is because -- this healthiest beverage contains polyphenols that are deemed to exert various protective effects, especially to the cardiovascular system.
Researchers from the Harvard Medical School reported that green tea may lower LDL cholesterol and triglycerides, which may be responsible for reducing the risk of death from heart disease and stroke. A study of 40,530 adults from Japan showed that individuals who drank more than five cups of green tea a day had a 26% lower risk of death from heart attack or stroke and a 16% lower risk of death from all causes than people who drank less than one cup of green tea a day.
Consuming green tea, either in a capsule form or as a beverage can offer modest reductions in LDL (Low-density lipoprotein) or "bad cholesterol". According to Harvard Health Publishing, a few studies found that green tea catechins significantly lowered LDL cholesterol and triglyceride levels.
One study found that green tea may block cholesterol from being absorbed in the intestine. Another study has demonstrated that green tea lowers total cholesterol and raises HDL or "good" cholesterol.
Green tea is often used as a key ingredient in fat burning supplements. This is because caffeine and catechins combinations can speed up metabolism and increase fat burning process. Green tea inhibits movement glucose molecules into adipose cells, regulates glucose levels after a meal that prevents insulin spikes and, accordingly, prevents the creation of body fat. Those subsequently prevents fat storage and reduce appetite.
"A small study from the United Kingdom demonstrated an increase in fat oxidation during moderate-intensity exercise and improvement in insulin sensitivity and glucose tolerance following acute ingestion of green tea extract".
Green tea has also been shown can promote a weight loss in obese and overweight adults with a variety of health problems. The study that conducted among patients with type 2 diabetes reported that after a two-month period, consumption of four cups caused a decrease in body weight, body mass index, waist circumference, and systolic blood pressure.
| Liver Protection
The liver is a metabolic organ involved in the synthesis and degradation of nutrients, toxins, and drugs. An analysis of numbers of studies has found that green tea consumption helps in the regulation of lipid metabolism and reducing fat accumulation in the liver. This fact is beneficial in the prevention and treatment of many diseases including, one of them is a nonalcoholic fatty liver disease.
| Diabetes Prevention and Management
Various studies have demonstrated beneficial effects of green tea not only on cardiovascular diseases and obesity but also on type 2 and type 1 diabetes by improving insulin sensitivity and reducing blood sugar levels.
The study in Japan has found that men who consumed a 3% concentration of green tea showed lower values of fasting blood sugar levels than those who consumed a 1% concentration. Other study reported that individuals who drink at least 2-3 cups of green tea a day had a 42% lower risk of developing type II diabetes.
Other research studies have shown that people with impaired glucose regulation "prediabetic state" have a significantly reduced risk for diabetes mellitus by drinking 16-30 cups of green tea per week.
| Cognitive Function
As mentioned earlier, green tea contains less caffeine than black tea and coffee, but sufficient enough to provide a quick effect. Caffeine that acts a stimulant and leads to improvements in several aspects of human brain function, such as vigilance, reaction time, improved mood, and memory.
Recent studies have suggested that green tea can effectively enhance the cognitive functions of human brains, specifically memory. It can bring promising benefits for the treatment of cognitive impairments, such as dementia. Even more, special green tea extract can reduce the risks of Alzheimer's disease.
| Overall Health Improvement
Green tea comprises of various bioactive compounds, for example, flavonoids and catechins that act as powerful antioxidants. The aforementioned substances can significantly reduce the formation of free radicals and protects cell damage. Another potent compound that's found in this tea is EGCG or Epigallocatechin Gallate that offers powerful medicinal properties.
Other than the aforementioned green tea benefits:
- Stress and chronic fatigue prevention
- Dental cavities and tooth decay prevention
- Improving rheumatoid arthritis by inhibiting inflammation and joint damage
- Skin inflammation and cancerous changes prevention.
Green Tea Side Effects
Green tea can lead to nausea, especially if it is taken on an empty stomach. Because of caffeine content, side effects are associated with central nervous system hyperstimulation, such as a headache, insomnia, agitation, vomiting, diarrhea, heartburn, and tremor. However, these effects are more likely to be noted with extremely high doses of green tea, such as 20 to 30 cups per day.
The polyphenol content of green tea (primarily tannins) can inhibit non-heme iron (found in plants and iron supplements) absorption. So, drinking too many polyphenols containing beverages (tea, coffee) can lead to anemia. Polyphenols also can limit calcium and healthy fat absorption.
Do not drink green tea with eggs, dairy, beans, greens, lean meat, and fish; consume green tea between meals. Not take any supplements (iron, fish oil, calcium) with coffee or green tea.
Avoid drinking tea with the drugs: antibiotics, ephedrine, clozapine, monoamine oxidase inhibitors, and phenylpropanolamine.