Green Tea (Camellia sinensis)

Written by Robin Warnken

            There are so many advertisements on the internet and that come into our inboxes that claim that green tea can help people lose weight or help us get a smaller waist.  Tea is a popular drink throughout the world as it has been found to be the second most consumed drink compared to water.1   The history of tea dates back to approximately 5000 years ago in China and was not nearly as tasty as it is today.  It was primarily used to treat illnesses, as it is today in most Chinese Medicine practitioners, or Doctors of Chinese Medicine.  Green tea has come to the forefront and gained popularity because it is rich in catechins.  Catechins are better known as polyphenols, or antioxidants.  The polyphenols that are found in green tea are:  epigallocatechin gallate (EGCg), catechin (C), epicatechin (EC), gallocatechin (GC), gallocatechin gallate (GCG), epigallocatechin (EGC), and epicatechin gallate (ECG).  Smaller amounts of caffeine, theanine, theaflavins, theobromine, theophylline and gallic acid are also found in green tea.1,2    

            Green tea can be found on the shelves of grocery stores among many other flavorful teas as well as in vitamin stores to promote wellness.  So, it is legal and is easy to buy.  Should we invest in several boxes of green tea and are the claims of weight loss with ingestion of green tea supported by research? 

Because of its history, many alternative and complementary medicine journals and studies back up the claim that green tea can reduce weight amongst other claims such as reducing tumors3, reducing atherosclerosis4 and reduces stress1.  Research studies have tested the use of green tea and have concluded positive results that back up the weight loss claims. 

Many people think it is the caffeine in green tea that helps increase weight loss.  Cooper et al. also questioned the fact that thermogenesis – or caloric expenditure - occurs with ingestion of green tea and that may be contributed by the caffeine content1, but a study published in the American Journal of Clinical Nutrition minimized the amount of caffeine in the green tea to reduce the thermogenic effect that caffeine has on the body and gain a greater understanding of the effect of green tea.  After consuming green tea with 690 mg of catechins daily for 12 weeks, the study concluded that those men, who were normal weight to overweight to begin with, had a decrease in waist  circumference (-3.4 +/- 0.5cm), skinfold thickness (-3.3 +/- 0.7mm), subcutaneous fat (-16.7 +/- 3.0cm2) and significant reduction in total fat area (-26.7 +/- 6.0cm2).2  Not only did this study conclude the reduction in fat loss, the levels of LDL, known as “bad cholesterol” were also reduced in the men that ingested the green tea daily compared to those who were given placebos. 

Another study found that ingesting green tea or black tea lowered blood glucose levels in elderly men and women that were not obese, there was no significant change in individuals that were already obese.  The results found that glucose levels, in individuals that eat a Mediterranean diet and have lived an active life, can be lowered as much as 5% if by drinking green, black, white or oolong tea.4  Reducing blood glucose levels can help reduce health concerns and increase the drive to feel better and exercise, losing weight and prolonging life in return.  Along the same lines, a study on the extracts of green, black and mulberry teas found that tea can reduce carbohydrate absorption that can increase weight loss and help with diabetic treatment.5  Many studies include other types of tea along with green, therefore it is important to note that more research needs to be done on green tea alone in order to have more conclusive evidence on its individual benefits.

            But, how much do we need to drink to reap the benefits that green tea has to offer?  The study focusing on the reduction of body fat in humans concludes that the ingestion of 690 mg of catechins per day will help reduce body fat.2   One serving of 100% Lipton Green Tea contains 190 mg of overall protective antioxidants per servings.6  In order to achieve weight loss benefits from green tea, a person has to ingest 3.6 cups of green tea per day.  An easy one to two cups per day can help reduce blood glucose, along with a healthy diet.4

There is no evidence that green tea is harmful to the body.  If someone decides to consume 3 or more cups per day, a decaffeinated option or a reduction in caffeine may be warranted to prevent unwanted side effects of caffeine ingestion. 

Green tea alone has not been proven to reduce weight loss, it is important to realize that it must be ingested along with a healthy diet and exercise plan.  Most of the studies that were found were from countries that ingest green tea, or other teas, regularly make healthy, lower fat choices regarding their food intake and lead active lifestyles.  Choosing green tea over soda or other beverages that we may pick up during the day are beneficial to the waistline as well as reduction in blood glucose levels which is significant in our increasingly sugar abundant world.    This is promising to those who are looking to retain and/or obtain their recommended weight and increase their health with the benefits of drinking green tea. 

 

 

 

 

 

References

1.      Cooper R, Morré D, Morré D. Medicinal benefits of green tea: part I. Review of noncancer health benefits. J Altern Complement Med. 2005;11(3):521-528.

2.      Nagao T, Komine Y, Soga S, et al. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. Am J Clin Nutr. 2005;81(1):122-129.

3.      Cho KN, Sukhthankar M, Lee SH, Yoon JH, Baek SJ. Green tea catechin (-)-epicatechin gallate induces tumour suppressor protein ATF3 via EGR-1 activation. Eur J Cancer. 2007;43(16):2404-2412.

4.      Polychronopoulos E, Zeimbekis A, Kastorini C, et al. Effects of black and green tea consumption on blood glucose levels in non-obese elderly men and women from Mediterranean Islands (MEDIS epidemiological study). Eur J Nutr. 2008;47(1):10-16.

5.      Zhong L, Furne JK, Levitt MD. An extract of black, green, and mulberry teas causes malabsorption of carbohydrate but not of triacylglycerol in healthy volunteers. Am J Clin Nutr. 2006;84(3):551-555.

6.      Lipton Tea Web site.  http://www.liptont.com/our_products/green_tea/grn_natural.aspx.   Accessed April 4, 2009.