Well-documented, green tea is a staple of alternative medicine in eastern culture. For centuries, uses have included improving blood and urine flow, relieving joint pain, improving disease resistance, promoting digestion, and improving mental processes.
Today, green tea remains a common herbal product used worldwide. A 2012 consumer survey found green tea extract ranked No. 12 among the top-selling US herbal dietary supplements. And patients with chronic diseases in general, tend to use herbal and phytochemical supplements more frequently among other healthy individuals.
Emerging small-scale studies note that green tea may help control cardiovascular, neurological, and neoplastic disease progression, and may even help prevent some forms of cancer. And in 2013, researchers from Penn State University suggested that the addition of decaffeinated green tea and exercise may help diabetics manage blood sugar spikes.
Where’s the benefit? The answer may lie in the way green tea is processed. One of the most important components in the manufacture of darker-colored teas is the introduction of moist, oxygen-rich air, which causes oxidation – resulting in withering and discoloration of the leaves. Green tea leaves, on the other hand, do not undergo this chemical oxidation. Instead, the leaves are run through a series of meticulous steaming, drying, and/or frying techniques, thereby retaining higher amounts of a group of polyphenols known as catechins. Some studies report as many as 90% of catechins are retained in this process.
Current antiobesity and antidiabetic studies involving green tea are looking at one catechin in particular – epigallocatechin-3-gallate (EGCG). While there is no fixed ratio for benefit per-say, dosages used in clinical trials examining EGCG have ranged from 3-10 cups per day (120 ml). A 2006 study of over 17,000 participants reported drinking three cups of coffee, or six cups of green tea was associated with reducing the onset of type 2 diabetes. And a 2013 meta-analysis involving over 1,100 individuals reported for those already diagnosed with the disease, consuming green tea may help decrease fasting glucose levels and help regulate insulin sensitivity.
While there is still much to be learned about green tea and potential benefit for additional patient populations – including individuals diagnosed with obesity and metabolic syndrome – more studies are on the way aiming to include greater sample sizes and a broader range of age and body mass index candidates; something we raise our glass to!
- Ahmed Albassam, BS Pharm, Ph.D. Candidate “Green Tea: An Update on Drug Interactions and Potential Therapeutic Effects in Diabetes and Obesity”. http://my.cop.ufl.edu/player/index.php?m=1312130860
- Liu K, Zhou R, Wang B, Chen K, Shi LY, Zhu JD, Mi MT. Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials. Am J Clin Nutr. 2013 Aug;98(2):340-8. doi: 10.3945/ajcn.112.052746. Epub 2013 Jun 26.
- Iso H, Date C, Wakai K, Fukui M, Tamakoshi A; JACC Study Group. The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among Japanese adults. Ann Intern Med. 2006 Apr 18;144(8):554-62.