Permeability refers to the ability of nutrients, microorganisms, and other constituents to pass through the cellular lining of any barrier. We will refer to it regarding the intestines and the gut barrier as “gut permeability.”

Personality refers to the enduring set of traits and styles that an individual exhibits, representing both dispositions—natural tendencies or personal inclinations—and ways in which the person differs from societal norms or the “standard person” (Bergner, 2020). Traits are tendencies to engage in specific behaviors or experience particular emotional states, while styles define how an individual characteristically approaches or performs actions. Traits are dispositions to engage in a certain kind of behavior or to experience certain emotional states, while styles are dispositions that define how a person does things.

A personality trait is a consistent internal characteristic and persistent tendency to think, feel, and behave similarly across time and situations (Farrington & Jolliffe, 2001),.

Peyer’s patches have an oval-shaped structure and are part of gut-associated lymphoid tissues (GALT) found along the entire length of the small intestine, just below the intestinal epithelium. Peyer’s patches (PPs) act as an immune sensor of the intestine due to their ability to distinguish between harmful and commensal microbes.

Phagocytes are a group of cells, including neutrophils and macrophages, that can engulf and digest foreign particles, such as bacteria and debris. They are essential components of the innate immune system’s defense mechanism.

Phagocytosis is a process in which cells, typically specialized immune cells like macrophages and neutrophils, engulf and digest foreign particles, such as bacteria or cellular debris. This mechanism is crucial in the immune system’s response to infection and tissue damage.

A phylum is a major category for classifying living organisms based on shared characteristics and evolutionary relationships. It helps organize diverse species into broad groups.

Plant-based diets include a variety of eating patterns that prioritize plant-derived foods, ranging from fully plant-exclusive diets like veganism to those that include some animal products, such as vegetarian or Mediterranean diets. These diets are often associated with health benefits, though they may not inherently be balanced unless they include a focus on whole, minimally processed plant foods.

A transient emotional state resulting from the satisfaction of a desire or a craving (as opposed to happiness, which refers to a lasting emotional state of contentment) (Gros, 2020).

Polyphenols are a diverse group of naturally occurring compounds found in plants, characterized by the presence of multiple phenol groups. They have antioxidant properties and are known for their potential health benefits, including reducing inflammation, protecting against chronic diseases, and promoting overall well-being. Common dietary sources of polyphenols include fruits, vegetables, tea, coffee, and certain nuts and seeds.