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Sugary soda disrupts the link between gut bacteria and immunity
Last reviewed: 27.07.2025
Drinking carbonated drinks containing white sugar alters the DNA of gut bacteria and affects the host's immune system. The good news? These effects are reversible.
The findings, by researchers from the Ruth and Bruce Rappaport Faculty of Medicine at the Technion – Israel Institute of Technology, Prof. Naama Geva-Zatorsky, PhD student Noa Gal-Mandelbaum, and other members of Geva-Zatorsky’s team, were recently published in the journal Nature Communications. Dr. Tamar Ziv and the Smoler Proteomics Center at the Technion assisted with the study.
Gut bacteria are important members of the microbial community in our bodies, known as the microbiome. These bacteria, which have co-evolved with humans over generations, are so important to human health in general and the development of the immune system in particular that we cannot function without them.
The human gut is constantly exposed to environmental changes. To adapt, our gut bacteria must adapt quickly. They do this through a process called functional plasticity, which allows them to change their behavior and function in response to factors such as neighboring microbes, our health, and what we eat.
In a previous study, Geva-Zatorski’s lab found that one way gut bacteria adapt to environmental changes is through DNA inversions — quick genetic switches that help them respond and defend themselves. In the current study, the researchers looked at how these DNA inversions occur in response to dietary factors. They found that drinking sodas containing white sugar can alter the DNA of gut bacteria and, in turn, affect the host’s immune system.
The study focused on Bacteroides thetaiotaomicron, an important member of the gut flora that is involved in preventing intestinal inflammation, maintaining the intestinal mucus layer, and protecting the host from invading pathogens. The researchers examined the effects of consuming various dietary components on the DNA inversion profile of these bacteria in vitro, in mice, and in humans.
They found that white sugar consumption caused DNA inversions in these bacteria, leading to changes in inflammatory markers of the immune system, including changes in T-cell populations, cytokine secretion, and intestinal permeability.
The good news is that these effects are reversible: once the mice stopped eating white sugar, the bacteria’s DNA inversions returned to their original state, and their immune systems returned to normal. This study highlights the importance of understanding the complex effects of diet on the microbiome and our health, and the researchers believe it could lead to tailored dietary recommendations to improve our immune system and overall health.