For thousands of years thirsty folks have turned to green tea for its purported health benefits (and they are many), but today's scientific tools are enabling researchers to really dig into its affects on the human body. The latest intriguing observations come from nutritionists at Ohio State University (OHU), who set out to study how the steamy beverage might limit obesity in mice and returned some positive results.
Recent research projects have uncovered an interesting mix of potential health benefits that green tea can offer, including everything from protecting sensitive teeth, dampening Alzheimer's symptoms, repelling bacteria and even preventing heart attacks. Previous studies have suggested that it can also be a factor in obesity through its anti-inflammatory effects on gut health, so the researchers drew up some experiments to explore this very idea.
"The results of studies looking at obesity management so far have been a real mixed bag," says Richard Bruno, the new study's lead author and a professor of human nutrition at OSU. "Some seem to support green tea for weight loss, but a lot of other research has shown no effect, likely due to the complexity of the diet relative to a number of lifestyle factors. Our goal is to figure out how it prevents weight gain. This will lead to better health recommendations."
The study took place over eight weeks and involved a group of male mice, with half of those fed a high-fat diet to induce obesity and the other half fed a normal healthy diet. Within those two groups, half of each had a green tea extract mixed through their food, constituting around two percent of their total diet, or the equivalent to a human drinking 10 cups a day. The scientists say female mice were not included as they are resistant to diet-induced obesity and insulin resistance.
Meanwhile, the researchers measured body weight, fat tissue, insulin resistance, inflammation in the intestines and fat tissue, the makeup of gut microbes, and how the gut bacteria and its derivatives shift into the bloodstream to promote inflammation. This allowed them to tease out a number of useful observations, primarily, that the high-fat mice whose diets were supplemented with green tea gained around 20 percent less weight than those whose were not. These mice also exhibited lower insulin resistance, a factor in the onset of diabetes.
These green tea-fed mice also featured healthier communities of microbes in the gut and less inflammation in the fat tissue and intestines. They were also less prone to leaky gut, where the wall of the small intestines are damaged and allow toxic products to flood into the blood stream.
"This study provides evidence that green tea encourages the growth of good gut bacteria, and that leads to a series of benefits that significantly lower the risk of obesity," said Bruno.
Although promising, it is still very early days for this research, even when viewed in the context of similar projects probing the health benefits of green tea in mice. It is unclear whether these results will translate to humans, and even if they do, whether we'd be better taking supplements or drinking tea as normal, due to the way the body metabolizes its antioxidants.
"Consuming a little throughout the course of a day with food, like the mice did in this study, might be better," Bruno says.
From here, Bruno and his team are working on a follow-up study in humans where they will investigate how green tea could prevent leaky gut, and hope that future research can further home in on how green tea consumption can help stave off obesity.
"Two-thirds of American adults are overweight or obese, and we know that just telling people to eat less and exercise more isn't working," he says. "It's important to establish complementary health-promoting approaches that can prevent obesity and related problems."
The research was published in the Journal of Nutritional Biochemistry.
Source: Ohio State University
