College students' mental health can be compromised by the exceeding demands of academia and other life stressors that can aversively impact their mood, sleep quality, and academic performance (Jordan et al., 2020; Silisteanu et al., 2022). Moreover, chronic exposure to high stress can increase risk of developing mental illness and other long-term health conditions, such as heart disease, diabetes, and cancer; highlighting the connection between psychological and physiological health (Bharwani et al., 2015; C. H. Liu et al., 2019; Ohrnberger et al., 2017). The relation between the brain's central nervous system and the gut's enteric nervous system may be better explained by the underlying mechanisms of the gut-brain axis, which can be directly and indirectly influenced by several lifestyle factors, including diet (Berding, Ahmed, et al., 2020; Clapp et al., 2017, Skonieczna-Zydecka et al., 2018). The purpose of this study was to investigate the effect of diet and lifestyle factors related to gut health on mental health among college students by employing a repeated measures design to assess diet composition and aspects of perceived stress across time. Results revealed a statistically significant three-way interaction between diet, stress, and sleep quality (p = < 0.001), with increased psychological stress associated with poorer diet and sleep quality. Additionally, an exploratory analysis was conducted to examine aspects of nutrition that have been shown to be associated with promoting gut health and brain function (Ayakdas & Agagunduz, 2023). The impact of consuming fiber rich diets comprised of microbiota accessible carbohydrates and other nutrients that influence psychobiotics are discussed to better understand the role of diet as a mediating factor between gut and brain health. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]