Green tea extract combined with exercise would improve liver health

New research highlights that green tea extract, combined with exercise, can reduce fatty liver disease in mice. Namely, fatty liver is a lesion of the liver corresponding to an overload of fat in the cytoplasm of hepatocytes. Today, in developed countries, the prevalence of fatty liver disease is estimated between 20 and 30% (and it tends to increase with the increase in the obese or diabetic population).

New combination of green tea extract and exercise reduces the severity of fatty liver disease (linked to obesity) by 75% in mice fed a rich diet, says new research from Penn State researchers in fat.

This study could therefore well indicate a future potential health strategy for human beings. "This result is important," says Joshua Lambert, associate professor of food science, because " nonalcoholic fatty liver disease is a significant global health problem, which is expected to worsen in the years to come. Due to the high prevalence of risk factors such as obesity and type 2 diabetes, fatty liver disease is expected to affect more than 100 million people by 2030. And there is currently no validated treatment for the disease", he added.

Green tea extract and exercise for a healthier life

As part of the study, mice fed a high-fat diet for 16 weeks who consumed green tea extract by regularly exercising by running on a wheel, were found to have only 'a quarter of the lipid deposits in their liver, compared to the control group of mice.

The mice that were treated with green tea extract alone or who were only exercising (without green tea extract) had about half the fat in their liver compared to the control group.

The results of the experiment are clearly indicated on these slides showing the liver tissue: the mice which consumed green tea extract and exercised regularly had only a quarter of the lipid deposits in their liver, by compared to those of a control group. The mice that were treated with green tea extract alone or that were only exercising had about half the fat in their liver compared to the control group. Credit: Joshua Lambert research group / Penn State

In addition to analyzing the liver tissue of the mice, the researchers also measured the protein and fat content of their stools. They found that mice that consumed green tea extract and exercised had higher lipid and fecal protein levels.

Processes nutrients differently

"By examining the livers of these mice after the study concluded and by screening their feces during the research, we saw that the mice that consumed green tea extract and exercised actually were processing nutrients differently -- their bodies were handling food differently," Lambert said.

"We think the polyphenols in green tea interact with digestive enzymes secreted in the small intestine and partially inhibit the breakdown of carbohydrates, fat and protein in food," he added. "So, if a mouse doesn't digest the fat in its diet, that fat and the calories associated with it pass through the mouse's digestive system, and a certain amount of it ends up coming out in its feces."

It may be significant, Lambert explained, that mice treated with both green tea extract and exercise had higher expression of genes related to the formation of new mitochondria. That gene expression is important, he said, because it provides markers that will help researchers understand the mechanism by which green tea polyphenols and exercise might work together to mitigate fatty liver deposits.

"We measured the expression of genes that we know are related to energy metabolism and play an important role in energy utilization," Lambert said. "In the mice that had the combination treatment, we saw an increase in the expression of genes that wasn't there before they consumed green tea extract and exercised."

Of course, more research is still needed to see if there is a synergy created by green tea extract and exercise, to reduce the fat deposited in the liver, or if the effects are simply additive. Note that the group of researchers led by Lambert, from the College of Agricultural Sciences (United States), have been studying for 12 years the health benefits of polyphenols (often called antioxidants) from green tea, cocoa, avocados and still other sources.

Towards improved cardiovascular health

In previous related research, Lambert and colleagues demonstrated that green tea extract and exercise together sharply reduced body mass and improved cardiovascular health of high-fat-fed mice. But because no human trials assessing the health benefits and risks of green tea combined with exercise have been conducted, he urges caution for people who decide to experiment with the health strategy on their own.

"I believe people should engage in more physical activity, and replacing high-calorie beverages with decaffeinated, diet green tea -- which has no calories -- is a smart move," he said. "Combining the two might have health benefits for people, but we don't have the clinical data yet." he added.


Mitigation of nonalcoholic fatty liver disease in high-fat-fed mice by the combination of decaffeinated green tea extract and voluntary exercise.

Weslie Y. Khoo, Benjamin J. Chrisfield, Sudathip Sae-tan, Joshua D. Lambert.

The Journal of Nutritional Biochemistry, 2020; 76: 108262

DOI: 10.1016/j.jnutbio.2019.108262

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