Green tea is one of the oldest beverages in the world, used medicinally for thousands of years in China and Japan. Its purported health benefits have contributed to growing popularity in the United States. There are 160 million Americans who drink tea, and 20% of the tea they purchase is green. Retailers promote green tea as a cure for maladies as diverse as stomach aches, depression, infections and obesity. Its global sales—in bags, bottles, capsules, powders or tinctures, or loose leaf—are expected to top $26 billion by 2028.
Green tea comes from the same plant as black tea, the evergreen shrub carmellia sinensis. Differences in processing give it a light green color, mild flavor and a high concentration of antioxidants, including Epigallocatechin-3-gallate (EGCG) and L-theanine. These powerful organic compounds fight free radicals in our bodies associated with disease and aging, and they have garnered considerable attention from the international scientific community.
Studies show that EGCG in green tea helps lower cholesterol levels and regulate blood sugar; it may reduce the risk of pancreatic, prostate and skin cancer, and has anti-inflammatory effects. A 300-milligram daily dose of EGCG is necessary for the health benefit: That’s three 8-ounce cups of green tea (try Korean jeoncha and Japanese sencha) or one capsule of extract depending on the brand (such as Zenwise or Zhou Nutrition).
L-theanine helps with sleep, anxiety and mental alertness. The recommended dose is 100 milligrams, available in capsule form. (8 ounces of brewed tea contains only 5 mg.)
The FDA has not approved green tea products for medical use, with one exception: an ointment made from green tea leaf extract used to treat genital warts.
Courtesy of Wikipedia
Although it has less than half the caffeine of black tea (and a quarter of the caffeine of coffee), green tea can cause palpitations and raise blood pressure in sensitive individuals. Check with your medical provider before you start drinking green tea regularly; it may interact with prescription drugs: beta-blockers such as atenolol and blood thinners (warfarin), and chemotherapy.
Consuming too much EGCG can also be dangerous. Since 1990 there have been 200 global cases of severe liver damage when consumers exceeded the daily dose of 800 milligrams. You can enjoy two to four cups a day without worry.
The newest U.S. trend in green-tea products is matcha, sold as a bright green powder and often used in smoothies, energy bars and baked goods. Derived from plants grown under tarps in a labor-intensive process, matcha has an earthy, grassy flavor and high levels of EGCG, L-theanine and caffeine. A typical cup containing a half teaspoon has twice the EGCG and twice the caffeine of a cup of green tea. Matcha is not available in tea bags: The powder must be whisked into suspension with hot water.
Mary Jenkins recently retired after nearly 40 years as a family practice physician in New York state.