Health Benefits of Green Tea (and Why Loose Leaf Tea is Best)
A large and growing body of research shows that drinking green tea can offer extraordinary health benefits. Like black tea, green tea is made from the leaves of the Camellia sinensis plant. However, unlike its black counterpart, green tea is not fermented during the manufacturing process, allowing its healing and health protecting compounds to stay largely intact. In this in-depth article, we dig into some of the most compelling health benefits of green tea. So grab a cup of green tea, sit back and enjoy:
1. Green tea boosts metabolism
Drinking green tea is a great way to rev up your metabolism as green tea is packed with metabolism-boosting flavonoids called catechins. When your metabolism is cranked into high gear, your body will burn more energy, which in turn can help you lose excess body weight.
In one clinical trial, 132 overweight/obese adults were given either a drink containing approximately 625 milligrams green tea catechins and 39 milligrams caffeine or a a control drink which contained the same amount of caffeine but no catechins. All participants followed a similar diet in terms of caloric intake and exercise regimen. At the end of the twelve week trial period, the participants were weighed: Both groups had lost weight, but those who had consumed the catechin-containing drink had lost substantially more weight than those who drank the control beverage.
2. Green tea – a natural acne treatment?
The weight loss promoting properties of green tea are among the most widely publicized health benefits of green tea, but the positive health effects associated with drinking green tea extend well beyond these benefits. Recent research suggests, for example, that adding green tea your anti-acne diet may help keep your skin free of pimples. Epigallocatechin-3-gallate (EGCG), one of the major catechins in green tea, has been shown to influence the production and actions of hormones that have been linked to acne breakouts. Green tea is also thought to have detoxifying and anti-inflammatory properties, which may further help keep acne at bay.
3. Strong antioxidant and anti-aging properties
Green tea, particularly green tea made from loose leaves, is an excellent source of antioxidants such as catechins. Antioxidants, as you may already know, are health-benefiting molecules that slow down aging and guard against disease. According to research conducted by the U.S. Department of Agriculture (USDA) on the antioxidant capacity of foods and drinks, green tea is superior to black tea in terms of antioxidant capacity. It appears that the enzymatic oxidation process (fermentation) used in the preparation of black tea leaves is responsible for the weaker antioxidant activity of black tea.
4. Anti-allergy benefits
Another green tea health benefit attributed to catechins, particularly epigallocatechin-3-gallate (EGCG), is the potential of green tea to provide relief from certain types of allergic reactions. In order to understand how EGCG in green tea fights allergies, it is important to understand how allergic reactions develop. Here's a summary:
Human mast cells produce histidine decarboxylase, an enzyme that helps histidine convert to histamine. Histamine is then attached to receptors in the immune system, a reaction that causes the typical symptoms associated with allergic reactions.
Traditional anti-histamines, which are used to treat allergic reactions such as hay fever, work by preventing histamine from attaching to the receptors in the immune system. In contrast, EGCG derived from green tea has been shown to prevent allergic reactions by a very different mechanism: it stops the reaction right at the beginning by inhibiting the initial histidine decarboxylation reaction. As anti-histamines tend to lose their effectiveness over time, green tea has been proposed as a potential alternative or complementary remedy for certain types of allergies.
5. Immune-boosting and stress-reducing properties
Green tea is rich in theanine, a beneficial amino acid found almost exclusively in Camellia sinensis plants. Research suggests that theanine in tea plants helps boost the immune system and prevent infections by enhancing the activities of a group of disease-fighting cells called gamma delta T cells.
As an added health benefit, theanine in green tea can help you manage stress and stay relaxed. These relaxing effects, which are usually experienced within 40 minutes after drinking green tea, are caused by the ability of theanine to stimulate the generation of alpha brain waves. The generation of alpha brain waves has been directly linked to mental relaxation. Theanine in green tea is also involved in the formation of gamma amino butrylic acid (GABA), a neurotransmitter with potential stress-reducing activity.
6. Anti-cancer effects
Catechins, the same compounds that are responsible for most of the above-listed health benefits of green tea, have been shown to be extremely effective at protecting cells against DNA damage which could lead to cancer. But the anti-cancer activities of green tea are not limited to the DNA-protecting effects of catechins; in vitro studies suggest that green tea can also inhibit nitrification, a bodily reaction that has been associated with the development of certain types of cancer, including stomach cancer and esophagus cancer.
In addition, green tea appears to be capable of suppressing urokinase, an enzyme that has been shown to be particularly active in cancer patients and that may play a key role in the spread of cancer cells.
While the evidence that green tea can help prevent cancer is convincing, people who already have cancer should consult with their doctor before using green tea as compounds in green tea have been shown to reduce bioavailability of certain anti-cancer drugs such as sunitinib (marketed as Sutent) and bortezomib (marketed as Velcade).
7. Improved cardiovascular health
There is some evidence suggesting that people who drink green tea may benefit from superior cardiovascular health. One randomized, double-blind, placebo-controlled study found that those study participants who were given green tea extract supplements had lower blood pressure after the three week trial period. Their systolic blood pressure and diastolic blood pressure decreased on average by 5 mmHg and 4 mmHg, respectively. In addition, their total cholesterol levels decreased by 10 mg/dL.
Another study investigating the benefits of green tea compounds on cardiovascular health found that polyphenol compounds in green tea were able to block the absorption of cholesterol in the intestines of the test animals. These polyphenols were also found to stimulate the excretion of cholesterol from the body.
TIP: Reap the maximum health benefits by using loose tea leaves
To maximize the health benefits of green tea, use loose tea leaves to brew your drink instead of tea bags. According to a 2008 study published in the journal Food Chemistry, the release of catechins from green tea leaves is significantly better from loose leaves than tea bags.
Another trick to boost the health benefits of your cup of green tea is to add a bit of lemon juice or other vitamin C rich juice to your tea. Research shows that vitamin C can make the catechins in green tea more available to the body.