University of Nebraska–Lincoln food scientists collaborated on a recently published clinical study of the health benefits from kombucha, a popular fermented tea, for people with Type 2 diabetes.

Scientists from the Department of Food Science and Technology partnered with clinicians from Georgetown University Medical Center and MedStar Health. Georgetown clinicians initiated the project and reached out to the Department of Food Science and Technology for its analytical expertise. Husker scientists, with assistance from the university’s Industrial Agricultural Products Center, analyzed the kombucha’s chemical composition and microbiological components, especially bacteria and yeast, and provided biostatistical analyses.

Subjects who consumed eight ounces of kombucha for four weeks saw their blood sugar levels decrease from 164 to 116 milligrams per deciliter. Blood sugar levels after four weeks with a placebo drink did not change significantly. The resulting academic paper, “Kombucha Tea as an Anti-Hyperglycemic Agent in Humans with Diabetes — A Randomized Controlled Pilot Investigation,” was published Aug. 1 in the journal Frontiers in Nutrition.

The authors emphasized that this was a small pilot study with only 12 participants. However, such studies are important because they provide a basis for follow-up studies with more participants, researchers said. The study was only the second human clinical study on kombucha and the first to include adults with Type 2 diabetes. Nebraska’s Food for Health Center “can be a good nucleus for these types of interactions between clinicians and basic scientists who are really interested in understanding how foods impact health,” said Jennifer M. Auchtung, an assistant professor of food science and technology who contributed biostatistical analysis for the project.

The center has had success with a variety of such collaborations, she said.

“These are really important partnerships that we’ve had for a long time, but the Food for Health Center has really galvanized those partnerships,” said Robert Hutkins, Khem Shahani Professor of Food Microbiology at Nebraska, who had worked previously with Daniel Merenstein, a family medicine physician and professor at Georgetown University. Merenstein and Georgetown colleague Chagai Mendelson are lead authors of the paper.

The project featured a “crossover design” by which one group of participants drank eight ounces of kombucha daily for four weeks and a second group consumed a placebo drink. After a two-month period to “wash out” the beverages’ biological effects, the kombucha and placebo were swapped between groups, and consumption of the drinks continued for four weeks.

The kombucha fermentation involves both bacteria and yeast, and Heather Hallen-Adams, associate professor of practice in food science and technology, provided detailed analysis of the yeast component. Another key Husker participant was Chloe Christensen, a graduate research assistant specializing in the study of fermented foods.

The composition of kombucha is complex, and much research lies ahead in analyzing and identifying the specific constituents, or combination of them, that provide the apparent health benefit. Possibilities for the beneficial “mechanism of action” include the microbes, but also the metabolites found in kombucha, which include ethanol, lactic and acetic acids, tea constituents and flavoring ingredients.

To bolster such studies in fermentation science, the Department of Food Science and Technology recently introduced a fermentation science minor.

The kombucha project illustrates the growing attention fermented foods are receiving among consumers and nutritionists. “Scientists have been engaged in the study of fermented foods and beverages since the very beginning of microbiology,” Hutkins said. “And not just academics. Industrial microbiologists have, too, whether it’s beer, wine, cheese, fermented vegetables. Even biofuels can be made by fermentation.”

This century, fermentation has attracted growing interest from consumers. The topic “checks all the boxes for why consumers are interested in it,” Hutkins said. “It’s natural, it’s holistic, you can do it at home. It tastes good, it’s unique, it’s local. And now, also in the last 20 years or so, nutritionists have gotten interested in it.”

As a result, he said, “it’s the perfect scenario where scientists, nutritionists and clinicians have all gotten involved in studying fermented foods.”