The Impacts of Anthocyanins on Gut Health: Microbiome Dynamics and Colorectal Cancer Cell Responses

Anthocyanin-rich foods such as berries and other colorful fruits have been widely studied for their potential to support gut health and reduce inflammation. These benefits may occur through direct effects on the lining of the gut or by influencing the gut microbiome, which is the community of bacteria in the digestive system. However, many previous studies used levels of anthocyanins that are much higher than what people typically consume, making it difficult to apply the results to real-world diets. This dissertation investigated how the gut microbiome responds to anthocyanin-rich foods when consumed as part of a Western-style diet, which is known to increase inflammation and raise the risk of colon cancer. Two studies were conducted. The first study used mice fed a Western diet supplemented with realistic amounts of anthocyanin-rich food powders. The second study tested the effects of purified anthocyanins on human colon cancer cells using concentrations that reflect typical dietary intake. In the first study, the gut microbiome changed as early as one day after introducing anthocyanin-rich foods. However, these changes were temporary and reversed after the foods were removed from the diet. Different foods produced different microbiome responses, likely because they contain different types of anthocyanins. In the second study, purified anthocyanins did not have significant effects on cancer cell growth, suggesting that other compounds in the food powder or extract or metabolites produced by gut bacteria may be responsible for any protective effects. Overall, this research emphasizes the importance of consistent consumption of anthocyanin-rich foods to maintain a healthy gut microbiome. It also highlights the need to study how these foods work in real-world dietary patterns and how gut bacteria may help unlock their full health benefits.