The human gut harbors a vast and diverse microbial ecosystem that plays a pivotal role in regulating metabolism, immune responses, and overall health. Among these microbes, trillions of bacteria—primarily located in the colon—interact intricately with dietary components, making the gut microbiota a central player in both health maintenance and disease development. This dynamic relationship has laid the foundation for the concept of functional foods and nutraceuticals, which go beyond basic nutrition to modulate physiological functions such as digestion, immunity, and even brain health. Growing scientific interest in the diet–microbiota–health axis has spurred investigations into how specific dietary interventions, including animal-derived functional foods, can positively influence gut microbial composition to promote human well-being.