Solving the Mystery of Tea Metabolism

Solving the Mystery of Tea Metabolism

February 24, 2015

Second only to water, tea is the most popular drink in the world. It can be hot. It can be iced. It comes in numerous flavors and types. The American Tea Association reports that black tea is the most popular, followed by green, oolong and white. Research links consumption of tea to the reduction of heart disease, obesity, diabetes and some cancers.

How tea is metabolized in the human body so that the health benefits are realized is not fully understood.


Shengim Sang, PhD

“The mystery is that black tea polyphenols have poor systematic bioavailability,” explained Shengmin Sang, PhD, associate professor and lead scientist for Functional Foods and Bioactive Compounds with the NCA&T Center for Excellence in Post-Harvest Technologies at the NC Research Campus in Kannapolis. “However, there are in vivo studies that found that black tea has beneficial health effects. So I am interested in figuring out how these compounds that are not bioavailable are still bioactive in the human body.”

Sang and his collaborator Christian Jobin, PhD, professor of medicine in the Division of Gastroenterology, Hepatology, and Nutrition at the University of Florida College of Medicine, believe there are clues waiting to be found in the human microbiome, the trillions of bacteria that live in the intestines and aid in digestion. Research is showing that the state of a person’s microbiome may be a variable that indicates whether or not they are healthy or have an increased risk for disease.

Through a $2.2 million, five year, R01 grant from the National Institutes of Health’s National Center for Complementary and Alternative Medicine (NCCAM), Sang and Jobin are working together as co-principal investigators to study the interaction between black tea polyphenols and gut microbiota and their impact on colitis-associated colon cancer.

“The goal of this grant is to identify microbial entities that are responsible for biotransformation of black tea polyphenols,” Jobin explained.

They will be looking specifically at how gut microbiota metabolize black tea polyphenols and how the microbiota-derived metabolites drive chemo-preventative effects.

“The third aim,” Sang continued, “is to determine how black tea affects the profile, structure and function of the microbiota.”

Christian Jobin

Christian Jobin, PhD

Jobin, who is an expert in the study of bacteria and host interaction and disease, will conduct the microbiome manipulation and animal studies at his laboratory in Florida. Sang will be in charge of the chemical analyses of the samples at his lab at the NCRC.

The new grant builds on research Sang and Jobin conducted in 2012. Two types of mice were given black tea polyphenols called theaflavins. Theaflavin metabolites were found only in pathogen-free mice, which have gut microbiota, and not the germ-free mice, which are free of all microorganisms including those found in the gut. These results led Sang and Jobin to conclude that microbiota play a critical role in the metabolism of black tea, and provided them the preliminary data needed to obtain their new grant.

“The impact of the study goes beyond black tea and colitis-associated colon cancer,” Sang said. “If we can figure out how black tea is metabolized by the microbiota, then these metabolites can be further studied for other diseases like heart disease.”

Learn more about NCAT’s research at the NCRC.

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