Green tea is one of the most commonly consumed beverages across the globe, largely due to its associated health benefits. New research offers yet another reason to drink this popular beverage, after finding that it could help to combat the negative health implications of a Western diet.
Researchers found that a compound in green tea called epigallocatechin gallate (EGCG) reduced the development of insulin resistance, obesity, and memory impairments in mice fed a high-fat, high-fructose diet.
Study co-author Xuebo Liu, Ph.D., of the College of Food Science and Engineering at Northwest A&F University in China, and colleagues recently reported their findings in The FASEB Journal.
The Western diet is generally defined as a diet rich in red and processed meats, high in saturated fats, refined sugars, and refined carbohydrates, and low in fruits, vegetables, whole grains, seafood, and poultry.
Unsurprisingly, following such a diet has been linked to weight gain and obesity, as well as the development of type 2 diabetes. What is more, studies have indicated that a Western diet may raise the risk of cognitive impairment.
The new study, however, suggests that the green tea compound EGCG could help to protect against the harms of a Western diet.
Testing EGCG in mice
Dr. Liu and team came to their findings by studying three groups of 3-month-old male mice.
For a total of 16 weeks, each group followed a different diet. One group of mice was fed a high-fat, high-fructose diet (HFFD), one group was fed an HFFD alongside 2 grams of EGCG in every liter of drinking water, while the remaining group was fed a standard diet (the controls).
At the end of the 16-week study period, as expected, the mice fed the HFFD had gained more weight than the control group. However, the weight gain was much less severe for mice whose HFFD was supplemented with EGCG.
Additionally, the team found that the mice fed HFFD plus EGCG were less likely to experience insulin resistance in response to an HFFD, as determined by the upregulation of specific brain pathways that control insulin signaling.
The memory of the mice was assessed with the Morris water maze test, a navigation task wherein researchers monitor rodents' ability to find an escape platform.
Compared with mice fed the HFFD, the researchers found that mice fed an HFFD plus EGCG were repeatedly much faster at finding the escape platform, and they also took a shorter path to locate it.
The team then removed the platform from the maze to test the rodents' memory in a probe trial, which measures how long a rodent spends in the "target quadrant," or the area of the maze where the platform used to be. A longer time spent in the target quadrant indicates better memory.
The researchers found that mice fed the HFFD plus EGCG spent longer in the target quadrant than the mice fed the HFFD alone.
The HFFD plus EGCG mice also had more platform crossings - that is, a greater number of crossings over the target location - indicating that these rodents had a better idea of where the escape platform was located previously.
While human trials are needed to confirm these findings, the researchers believe that EGCG not only has the ability to reduce the development of insulin resistance and weight gain in response to a Western diet, but it could also protect the brain.
"To our knowledge, this study is the first to provide compelling evidence that the nutritional compound EGCG has the potential to ameliorate HFFD-triggered learning and memory loss."