Will green tea help you lose weight?

This interview content is written by Dr Dae-Kyu Song, the corresponding and responsible author of the manuscript shown at “Park, Jae-Hyung et al. (2013).
Green tea extract with polyethylene glycol-3350 reduces body weight and improves glucose tolerance in db/db and high-fat diet mice.
Naunyn-Schmiedeberg’s Archives of Pharmacology. DOI 10.1007/s00210-013-0869-9“.

Dr Jae-Hyung Park is the first author of the manuscript and a graduate student
of Dr. Dae-Kyu Song

MedicalResearch.com: What are the main findings of the study?

Answer: At doses which could be achieved by drinking green tea on a daily basis, it has been known that green tea extract (GTE) inhibits intestinal glucose and lipid absorption when it is present in the intestinal tract. It is a reason why green tea consumption has been known to be beneficial for controlling obesity and type 2 diabetes. However, we have found that, after the intestinal absorption of GTE itself, the circulating GTE can elevate blood glucose levels by blocking cellular glucose uptake in most tissues, thereby limiting glucose utilization of the tissues. Therefore, we have tried to prolong the residence time of GTE in the intestine and block the intestinal absorption of GTE, by adding non-toxic polymer polyethylene glycol (PEG) to GTE. As a result, in 4 week treatment, the GTE+PEG regimen dramatically helps obesity-induced diabetic mice lose body weight and ameliorate glucose intolerance. Interestingly, GTE alone is without any effect.

MedicalResearch.com: Were any of the findings unexpected?

Answer: Although many investigators have found that GTE hinders cellular glucose uptake in most tissues, this impact on type 2 diabetes has been overlooked. Hindrance of cellular glucose uptake induces insulin hypersecretion from pancreatic beta cells to normalize blood glucose levels, resulting in early beta-cell exhaustion. Beta-cell exhaustion owing to chronic glucose overload is an important mechanism for developing type 2 diabetes. This harmful effect of GTE in the circulation can countervail the beneficial intestinal effect of GTE for lowering energy intake.

MedicalResearch.com: What should clinicians and patients take away from your report?

Answer: Overuse of green tea, in particular, between meals, should be avoided, because it can more elevate blood glucose levels during the following postprandial period, leading to unnecessary insulin hypersecretion.

What recommendations do you have for future research as a result of this study?

 

Answer:

This interview content is written by Dr Dae-Kyu Song, the corresponding and responsible author of the manuscript shown at “Park, Jae-Hyung et al. (2013).
Green tea extract with polyethylene glycol-3350 reduces body weight and improves glucose tolerance in db/db and high-fat diet mice.
Naunyn-Schmiedeberg’s Archives of Pharmacology. DOI 10.1007/s00210-013-0869-9“.

Dr Jae-Hyung Park is the first author of the manuscript
and a graduate student of Dr. Dae-Kyu Song

 

MedicalResearch.com: What are the main findings of the study?

Answer: At doses which could be achieved by drinking green tea on a daily basis, it has been known that green tea extract (GTE) inhibits intestinal glucose and lipid absorption when it is present in the intestinal tract. It is a reason why green tea consumption has been known to be beneficial for controlling obesity and type 2 diabetes. However, we have found that, after the intestinal absorption of GTE itself, the circulating GTE can elevate blood glucose levels by blocking cellular glucose uptake in most tissues, thereby limiting glucose utilization of the tissues. Therefore, we have tried to prolong the residence time of GTE in the intestine and block the intestinal absorption of GTE, by adding non-toxic polymer polyethylene glycol (PEG) to GTE. As a result, in 4 week treatment, the GTE+PEG regimen dramatically helps obesity-induced diabetic mice lose body weight and ameliorate glucose intolerance. Interestingly, GTE alone is without any effect.
MedicalResearch.com: Were any of the findings unexpected?

Answer: Although many investigators have found that GTE hinders cellular glucose uptake in most tissues, this impact on type 2 diabetes has been overlooked. Hindrance of cellular glucose uptake induces insulin hypersecretion from pancreatic beta cells to normalize blood glucose levels, resulting in early beta-cell exhaustion. Beta-cell exhaustion owing to chronic glucose overload is an important mechanism for developing type 2 diabetes. This harmful effect of GTE in the circulation can countervail the beneficial intestinal effect of GTE for lowering energy intake.

MedicalResearch.com: What should clinicians and patients take away from your report?

Answer: Overuse of green tea, in particular, between meals, should be avoided, because it can more elevate blood glucose levels during the following postprandial period, leading to unnecessary insulin hypersecretion.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Answer:  As these data show, GTE alone appears not to be effective in obesity and type 2 diabetes at the dose that is normally achieved by a cup of green tea. Of course, the greater doses of GTE will have greater side effects. However, mixture of GTE with PEG is effective in both metabolic diseases. Probably this is due to block the intestinal absorption of GTE itself. It has been accomplished in obesity and diabetes mice models. In the future, it should be tested in humans in order to evaluate whether it is also applicable for human obesity and type 2 diabetes. Next, non-absorbable GTE derivatives could be synthesized. Because GTE is effective in inhibition of both glucose and lipid, it will be better against obesity and obesity-induced diabetes than drugs targeting either glucose or lipid.

Updated: April 30 2013

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