Do you know that tea ranks as the second most consumed beverage in the world? Water stands in the first position. Green tea is amongst the healthiest and most beneficial drinks in the world. Though it has been used in Chinese medicine to treat various ailments for centuries, it has gained popularity as a health drink in the western world recently. Green tea is a super healthy drink since it is a rich source of antioxidants, flavonoids and phytonutrients. It also contains many B vitamins, folate, magnesium, potassium and manganese. There are several health benefits of green tea such as it improves cardiovascular health, lowers cancer risk, prevents Alzheimer’s disease, improves brain function, aids in weight loss, strengthen bone health, promotes eye health, etc.
In this article, we will learn more about this super beverage and its amazing health benefits in detail.
What is green tea?
Green tea is made from the leaves of Camellia sinensis plant. Green tea leaves are not fermented so; they retain their antioxidants. In fact, 30 percent of the dry weight of green tea leaves consists of flavonoids which include catechins and their derivatives (1). T
he most abundant catechin in green tea is epigallocatechin-3-gallate, which plays a pivotal role in the health benefits of green tea in a disease like cancer.
Green tea nutrition
It is a common notion that green tea does not caffeine. But the fact is that green tea has caffeine in the amount of 25 mg per 8-ounce (237 mL) of serving.
However, the caffeine amount in green tea is low as compared to black tea or coffee. It is somewhat half of the amount of caffeine present in a cup of black tea.
Green tea is calorie free when there is no sweetener in it. Other compounds of green tea are presented below in the table (2).
|Compounds||Green Tea Infusion|
Health benefits of green tea
Green tea is considered to be highly beneficial to many aspects of our health. Here are some of the benefits of green tea that are supported by medical research.
1. Green tea protects our heart by reducing cholesterol
According to many studies the flavanols and anthocyanin antioxidants found in green tea improve cardiovascular health. This is one of the top health benefits of green tea that is likely effective.
Green tea also increases the antioxidant capacity of the blood, and this helps to prevent heart disease. In fact, research shows that people who drink green tea have 31 percent lower risk of developing heart disease (4).
2. Helps lower the risk of cancer
It is a well-known fact that oxidative damage to cells can cause cancer and antioxidants play a crucial role in preventing this damage. Green tea is a rich source of many antioxidants that can reduce the risk of cancer.
According to a meta-analysis of various observational studies, women who drank green tea had 20 to 30 percent lower risk of developing breast cancer (5).
According to a study on Japanese men, men who drank green tea had a 48 percent lower risk of developing prostate cancer (6). Drinking green tea is also beneficial in lowering the risk of developing colorectal cancer.
3. May help prevent Alzheimer’s
Studies have shown that catechins in green tea can protect against Alzheimer’s disease (7). According to a 2004 study done at the University of Newcastle, green tea prevents the breakdown of acetylcholine, a neurotransmitter linked with memory.
Green tea also inhibited the enzyme known as BuChE and beta-secretase, which are found the brain of Alzheimer’s patients. According to another Japanese study, protein plaques associated with Alzheimer’s disease can cause an increase in brain cell damage (8).
4. Can improve brain function
Caffeine is present in the green tea. It helps to block the neurotransmitter called adenosine in the brain. It helps in increasing the firing of the neurons and the concentration of the neurotransmitters like dopamine and norepinephrine (9).
Caffeine has many positive effects on our health including mood, reaction time and memory. Green tea also contains L-theanine, which increases brain serotonin, dopamine and GABA levels (10).
This helps in reducing stress and increases the production of alpha-brain waves. Caffeine and L-theanine together help improve brain function.
5. May help prevent type-2 diabetes
Green tea is helpful in preventing diabetes because it contains polyphenols. Polyphenols help regulate glucose in the body, which helps to prevent and control diabetes.
A 2013 study highlighted the potential benefits of having green tea when it comes to diabetes and obesity (11). According to an analysis of 17 different studies, green tea improves insulin sensitivity and reduces blood sugar levels (12).
6. Improves metabolism and promotes fat oxidation
One of the best health benefits of green tea is weight loss. Regular and moderate consumption of green tea is also known to improve metabolism and hence help in weight loss.
Epigallocatechin gallate (EGCG) is one of the most important antioxidant ingredients of green tea. It increases our body metabolism and ability to burn fat.
According to a study published in the American Journal of Clinical Nutrition, green tea helps improve our metabolism and increase fat oxidation (13).
According to another study, green tea increases fat oxidation by 17 percent (14). Green tea is also beneficial in reducing belly fat. According to a 12-week study, consumption of green tea helped in decreasing body fat percentage, body weight and belly fat (15).
7. Improves dental health
According to a 2016 study, green tea may help protect against cavities, gum disease and bad breath. The catechins present in green tea can kill bacteria and prevent infection. The primary bacteria in the mouth is Streptococcus mutans.
This bacterium is known to cause cavities and bad breath. Drinking green tea can inhibit the growth of Streptococcus mutans and thus reduce the chances of cavities and bad breath (16).
8. Promotes healthy bones and protect against osteoporosis
According to researchers from Hong Kong, green tea may be helpful in keeping our bones strong and healthy. These researchers from Institute of Chinese Medicine say that epigallocatechin (EGC) present in green tea stimulates the action on an enzyme that promotes bone growth by 79 percent.
The catechins in green tea promote osteoblastic activity and inhibit osteoclast differentiation. This means that the catechins increase bone mineralisation and protects against osteoporosis.
9. Improves eye health
Catechins in green tea help protect the tissues of the eye from glaucoma and other eye diseases. According to a study published in Journal of Agriculture and Food Chemistry, when rats were fed green tea extracts, different parts of their eyes absorbed different amounts of catechins.
Though more research is needed to study the effects of these catechins in detail, the findings of this study suggest that green tea is helpful in keeping our eyes healthy.
10. Helps to reduce stress
Recent Japanese research has shown that drinking at least five cups of green tea a day can help in reducing stress by 20 percent as compared to those who drank just one cup of green tea.
Green tea contains L-theanine, an amino acid that helps in relaxing the brain. L-theanine acts on GABA neurotransmitters by increasing their concentration. GABA also influences the levels of serotonin and dopamine, which are known as happy hormones.
11. Green tea might help in skin disorders
A study (17) on mouse model suggests that green tea might be of therapeutic value in the treatment of skin diseases such as psoriasis or psoriasiform skin disorders.
It was found that green tea has polyphenol, which induced an enzyme, caspase 14, in the epidermal layer of the skin via MAPK (Mitogen-activated protein kinases) pathways. Overall, it reduced psoriasiform lesions in the mouse flaky skin.
12. Protect against Parkinson’s disease
Parkinson’s disease is a neurodegenerative disorder, and a study (18) suggests that drinking tea could lower the risk of this disease. Green tea polyphones, such as EGCG, has a neuroprotective effect.
It was found that people who drank 1 cup of tea showed a protective effect against Parkinson’s disease than who did not consume anything.
13. Positive effects on blood pressure
In a study (19), it was observed that long-term (more than 12 weeks) consumption of green tea could potentially help in the reduction of systolic and diastolic blood pressure. It can also help people with lower blood pressure.
How to make green tea?
- Don’t add green tea to boiling water. The boiling water reduces the number of catechins in green tea.
- Boil water and then let it rest for about ten minutes. Pour it over green tea leaves and brew it for about a minute before you drink it.
- Add lemon to green tea. The vitamin C in lemon makes it easier to absorb the beneficial catechins in green tea.
- Avoid adding milk to green tea. The dairy makes it difficult for the body to absorb catechins.
What is the best time to drink green tea?
- Do not drink green tea early in the morning on an empty stomach as it may damage your liver.
- Drink green tea at least two hours before or after a meal as it may interfere with the absorption of essential minerals in the food.
- Do not drink green tea too close to your bedtime. The caffeine and L-theanine in this tea may interfere with your sleep and keep you up at night.
- If you want to lose weight, have a cup of green tea before you exercise.
What are the other forms of green tea?
The popular form of green tea is available in tea bags. But there are different versions which are available at the nearby store.
- Green tea bags
- Loose leaf of green tea
- Powder form
- Twig teas (made up of twigs of tea plant)
- Green tea supplements in the form of capsule or liquid
- Bottled version with added sugar or artificial sweetener
You should avoid powdered green tea since you would end up drinking leaf suspension instead of its infusion. As a result, you will consume more caffeine.
Green tea loose leaves are better than tea bags as they contain less caffeine. Twig teas are made up of tea plant twigs. They are low in caffeine content.
Side effects of green tea
You should consume 2-3 small cups of green tea in a day for getting its maximum health benefits. Although green tea is a healthy drink, it can pose some health issues if consumed in excess.
Also, if you are suffering from some health disorders, such as bleeding, anxiety, heart condition, diarrhea, high blood pressure, anaemia, IBS, liver disease, etc., then you should avoid green tea as it contains a small amount of caffeine.
Pregnant ladies or new mothers are not recommended to have this beverage. Green tea caffeine content might pass into breast milk and affect infant’s health.
Final words on health benefits of green tea
Till now you must have seen several health benefits of green tea. But one thing is for sure that green tea should be consumed in moderation, i.e. 2-4 cups/daily, for achieving the maximum health benefits.
Studies of shown that long-term consumption of green tea has benefitted people suffering from high and low blood pressure, neurodegenerative disorders, cardiovascular problems, type-2 diabetes, etc.