How Drinking Green Tea Affects An American Diet

Green tea has been used for thousands of years as medicine due to its health benefits. The light green liquid is loaded with antioxidants and nutrients that help improve our wellbeing. Now, a study published in The FASEB Journal suggests a compound in green tea can combat the negative health effects of a Western Diet, including weight gain, type 2 diabetes, and poor brain function.

This diet, also dubbed the "American" diet, is defined by foods rich in red and processed meats, high in saturated fats, refined sugars, and refined carbohydrates while being low in fruits, vegetables, whole grains, seafood and poultry.

Researchers of the College of Food Science and Engineering, Northwest A&F University, in Yangling, China, found green tea extract — epigallocatechin gallate (EGCG) — reduced the development of insulin resistance, obesity, and memory impairments in a group of mice fed a high-fat and high-fructose diet (HFFD). Gallated catchin (GC) in green tea acutely reduces blood glucose levels through its activities in the alimentary tract — part of the digestive system — while increasing the glucose level when in circulation by blocking normal glucose uptake into the tissues. In other words, this action helps prevent type 2 diabetes and obesity from developing.

"The ancient habit of drinking green tea may be a more acceptable alternative to medicine when it comes to combatting obesity, insulin resistance, and memory impairment," said Xuebo Liu, author of the study, in a statement.

To assess the effects of EGCG on consumers of a Western diet, Liu and her colleagues separated young adult mice into three groups: a group of mice fed a HFFD; a group fed both a HFFD with two grams of EGCG in every liter of drinking water; and a group fed a standard diet. The mice were then tested on a wide range of parameters, including a water maze memory test to test their cognitive and memory function in a probe trial. This is used to measure how long the mice spend in a "target quadrant" or area of the maze where the platform used to be before the researchers removed it.

The findings revealed the mice eating HFFD plus EGCG were less likely to gain more weight and experience insulin resistance in response to a HFFD. The supplementation of EGCG seemed to counter the effects of the Western diet. In addition, the mice who consumed EGCG performed better on the Morris water maze; the mice were repeatedly much faster at finding the escape platform; and they also took a shorter route to locate it. The researchers noted insulin function was better in the nervous system of mice fed EGCG, suggesting the compound has a neuroprotective effect on the brain, specifically the hippocampus — responsible for learning and memory.

"Many reports, anecdotal and to some extent research-based, are now greatly strengthened by this more penetrating study," said Thoru Pederson, Editor-in-Chief of The FASEB Journal.

Further study is needed to confirm if researchers can replicate these findings in human trials. However, there is scientific data that suggests green tea can ward away various health ailments, like metabolic syndrome. For example, a 2013 study found drinking green tea for eight weeks was associated with significant increases in blood antioxidant capacity and glutathione levels, which may improve the body’s antioxidant protection in those with metabolic syndrome.

Green tea isn't part of a normal Western diet, but starting to drink the medicinal tea influences our health for the better, as further research focuses on EGCG's effects on our mind and body.

Source: Mi Y, Qi G, Fan R et al. EGCG ameliorates high-fat– and high-fructose–induced cognitive defects by regulating the IRS/AKT and ERK/CREB/BDNF. The FASEB Journal. 2017.