Green Tea Will Not Result in Weight Loss Without This One Ingredient
Green tea is often recommended for its purported benefits of helping individuals lose weight and control their blood glucose sugar levels. However, to date, thorough scientific review of these benefits of drinking green tea have not been conclusive and furthermore may show that drinking too much green tea (or an extract of green tea) can actually increase insulin resistance―a negative health consequence in obese and diabetic patients.
In a recent article published in the Springer journal Naunyn-Schmedeberg’s Archives of Pharmacology, researchers investigated the effects of one of green tea extract’s active ingredients―gallated catechins―on body weight and glucose intolerance in both diabetic mice and normal mice that were fed a high-fat diet.
In a previous study the researchers had found that gallated catechins from drinking approximately one cup of green tea are beneficial toward reducing blood glucose levels. To achieve enough of the gallated catechins to also decrease lipid uptake from the gut, the researchers found that it required significantly more cups of green tea daily. However, a problem with drinking significant amounts of green tea that the researchers discovered is that by doing so, the gallated catechins buildup in the blood circulation and actually have a negative effect on blood sugar levels by increasing insulin resistance.
A potential solution to this problem hypothesized by the researchers was to find a way to prevent high doses of green tea gallated catechins from leaving the gut and reaching the bloodstream. One way to accomplish this the authors decided was to add a non-toxic resin called “polyethylene glycol” to bind the gallated catechins in the gut to prevent their absorption into the blood.
In the study, the researchers tested the effects of green tea extract on body weight and glucose intolerance in both diabetic mice and normal mice fed a high-fat diet. The high fed diet consisted of green tea extract alone in one set of experiments, and green tea extract plus polyethylene glycol in another set of experiments.
What the researchers found was that mice fed green tea extract alone did not lose weight or have improved glucose intolerance. However, when mice were fed green tea extract with polyethylene glycol, there was a significant reduction in body weight gain while on a high fat diet. Furthermore, the researchers found that there was also a significant reduction in insulin resistance and reduction in glucose intolerance in both the normal mice on a high fat diet and the diabetic mice.
The authors of the study attribute their findings to the polyethylene glycol prolonging the amount of time the gallated catechins remained in the gut and thereby limited the amount of glucose absorbed and making its way to the blood.
According to a news release by Springer journals, the authors concluded that “dietary green tea extract and polyethylene glycol alleviated body weight gain and insulin resistance in diabetic and high-fat mice, thus ameliorating glucose intolerance. Therefore the green tea extract and polyethylene glycol complex may be a preventative and therapeutic tool for obesity and obesity-related type 2 diabetes without too much concern about side effects.”
The take-home message to this study is that moderate green tea intake consisting of 1-2 cups per day during a meal may be beneficial since the gallated catechins entering the circulation will be minimal. And, that the adding of polyethylene glycol to green tea or its extract form merits further study to determine whether this may be an effective way to help individuals lose weight and control their blood sugar levels while drinking significant amounts of green tea daily.
For additional information about the benefits of catechins from green tea, click on the link titled “Latest News on Green Tea Extract for Breast Cancer Prevention.”
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Reference: "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; Jae-Hyung Park et al.