The health benefits of the tea leaf Camellia sinensis are derived from a group of phytochemicals known as polyphenols. Polyphenols in fresh green tea leaves are present as a series of chemicals called catechins. The dominant and most biologically active among the catechins, (-)-epigallocatechin-3-gallate (EGCG), has been shown to induce expression of glutathione S-transferase, glutathione peroxidase, glutamate cysteine ligase, heme oxygenase-1, and other enzymes that protect a variety of cells, including cultured neurons, against oxidative stress-induced cell death. EGCG modulates the redox-sensitive transcription factor Nrf2, which plays a key role in activating detoxifying enzyme HO-1, as well as other phase II enzymes.
Green Tea Leaf Extract Green tea polyphenols protect erythrocytes (red blood cells) from oxidative stress. In research studies, EGCG supported healthy insulin activity, protected the pancreatic cells by reducing undesirable cytokines (e.g., interleukin-1 beta), and reduced interferon-gamma–induced nitric oxide production—an excess of which may cause free radical damage. Furthermore, it was found that the polyphenols triggered genes that inhibit activation of NF-kappaB and reduced the level of messenger RNA for the hepatic gluconeogenic enzymes, which convert non-carbohydrate sources into glucose. EGCG has been shown to support healthy immune function, support the endocrine system, and promote fat oxidation beyond what would be explained by its caffeine content.
Many of the wide range of health benefits derived from green tea are dose-dependent, and most Americans are not willing to consume the necessary 5-10 cups of tea a day to gain its advantages. Careful processing of the tea into an extract highly concentrates the key beneficial constituents. Each 600 mg capsule of Green Gene contains 80% polyphenols, 60% catechins, and 30% EGCG. This is equivalent to approximately 10 cups of green tea. Each capsule contains 36-45 mg of caffeine per serving, roughly the equivalent of a can of cola and less than the 95-200 mg of caffeine in an 8-oz cup of brewed coffee. Naturally occurring caffeine in green tea is believed to act synergistically with the polyphenols.
In summary, green tea’s benefits are based upon four actions: 1) it is a powerful antioxidant that protects against DNA damage; 2) it induces detoxifying enzymes; 3) it supports gene signaling, which helps regulate cellular growth, development, and apoptosis; and 4) it selectively improves the function of the intestinal bacterial flora.
Dr. Michael Hall
Miami’s Top Doctor
The Dr Truth Show podcast is a long form conversation hosted by board certified physician and author Dr. Michael Hall, MD with friends and guests that have included patients, health care industry leaders, artists, and beyond.