Known for thousands of years by Asian civilizations and consumed for its many therapeutic virtues, it is more recently that the benefits of Green Tea have been confirmed by modern science. Due to its antioxidant powers, the health benefits of Green Tea are of great interest in medical research, particularly with regard to degenerative diseases, cardiovascular diseases and cancer prevention.
Catechins, powerful antioxidants
Green Tea contains many antioxidant substances from the catechin family, the main one being EGCG (epigallocatechin-3-gallate). Catechins are very powerful antioxidants belonging to the flavonoid class, substances that give a slightly bitter taste to tea leaves.
Studies have shown that Green Tea appears to increase the body’s resistance, energy and endurance levels, as well as athletic and mental capacities. It is believed to progressively strengthen the organs and glands important for the delivery of available energy to the body. Thanks to its detoxifying action, Green Tea appears to improve the functioning of organs and quality of blood, boosting the body’s physical vitality.
"These results support and substantiate traditional consumption of green tea as protection against lipid peroxidation in the liver, blood serum, and central nervous tissue."
Skrzydlewska E et al., "Protective effect of green tea against lipid peroxidation in the rat liver, blood serum and the brain." Phytomedicine. 2002: 9(3): 232-238.
With a high concentration in theanine (an amino acid), Green Tea is known for its soothing action and calming effect. It relaxes the body, and relieves tension, nervousness and anxiety.
"Thus, it was suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation."
Kimura K et al., "L-Theanine reduces psychological and physiological stress responses." Biological psychology. 2007; 74(1) : 39-45.
The catechins in Green Tea are believed to promote improved oxygenation of the cerebral cortex, thus stimulating memory. Its components could also help inhibit the formation of certain proteins that cause neurodegenerative diseases, such as Alzheimer’s and Parkinson’s, by limiting oxidation and inflammation of the brain.
"Furthermore, green tea consumption has been recently reported to act positively against neurodegenerative diseases such as Parkinson and Alzheimer disease."
Cabrera C, Artacho R, and Giménez R, "Beneficial effects of green tea—a review." Journal of the American College of Nutrition. 2006; 25(2): 79-99.
The potential effects of polyphenols (particularly EGCG) on glucose metabolism work on 3 levels:
1. Decrease in the intestinal absorption of glucose
2. Improved sensitivity of pancreas receptors to glucose
3. Improved absorption of glucose by peripheral tissues
In type 2 diabetes, Green Tea is believed to help regulate glucose levels, reducing the risk of resistance to insulin.
"The anti-diabetic effect of polyphenols, particularly flavonoids within selected functional foods, is promising. Clinical evidence suggests that popular herbal tea ingestion (e.g., green tea, black tea, and yerba maté) and coffee drinking have direct and indirect protective outcomes for T2DM and associated cardiovascular disease."
Alkhatib A et al., "Functional foods and lifestyle approaches for diabetes prevention and management." Nutrients. 2017; 9(12): 1310-1328.
Green Tea is considered as helpful in draining and eliminating toxins from the body. Researchers have identified certain antioxidants – particularly EGCG – that are capable of increasing the speed at which our body fat is burned. Thanks to their diuretic properties, the catechins in Green Tea are considered to help prevent water retention and eliminate toxins from the body.
"The results indicated that polyphenols and polysaccharides were responsible for the suppressive effect of green tea extracts on body weight increase and fat accumulation."
Xu Y et al., "The anti-obesity effect of green tea polysaccharides, polyphenols and caffeine in rats fed with a high-fat diet." Food & function. 2015; 6(1): 296-303.
Green Tea is thought to improve the health of the heart and cardiovascular system, due to its concentration in theine and its many antioxidants, by
- Stimulating cardiac activity
- Relaxing blood vessel walls
- Limiting the formation of fatty deposits that lead to arterial obstruction.
Studies have also shown that Green Tea has the capacity to prevent the intestinal absorption of cholesterol and the formation of blood clots.
"Consuming green tea is associated with a decrease in all types of mortality, including that caused by cardiovascular disease."
Kuriyama S et al., "Consommation de the vert et mortalité par maladie cardio-vasculaire, cancer et de toutes causes au japon l'étude Ohsaki." Journal of American Medical Association. 2006; 296(10): 1255-1265
Thanks to its many antioxidants, Green Tea extract is considered to have the power to both lower bad cholesterol and increase good cholesterol.
"Green tea significantly reduces serum cholesterol levels in cholesterol fed rabbits."
Aftabuddin M et al., "Effect of green tea on serum cholesterol level in cholesterol fed rabbits." Bangabandhu Sheikh Mujib Medical University Journal. 2014; 7(2) : 91-94.
A powerful antioxidant rich in vitamin E, Green Tea has a positive impact on skin cells. It is believed to neutralise free radicals involved in the ageing process and prevent wrinkles and skin damage.
The polyphenols contained in Green Tea may also protect the skin from the harmful effects of the sun and UV rays. They could help maintain DNA integrity in cells and membranes.
"Accumulating evidence suggests that green tea polyphenols confer protective effects on the skin against ultraviolet (UV) irradiation-induced acceleration of skin aging, involving antimelanogenic, antiwrinkle, antioxidant, and anti-inflammatory effects as well as prevention of immunosuppression."
Roh E et al., "Molecular mechanisms of green tea polyphenols with protective effects against skin photoaging." Critical reviews in food science and nutrition. 2017; 57(8): 1631-1637.