Fruits play a significant role in human nutrition, since they are good to excellent sources of vitamins, dietary fibers, and phytonutrients such as polyphenols and carotenoids. While many fruits have a long history of use as traditional remedies in cultures worldwide, scientific evidence to help explain the biochemistry, physiology and nutrition affected by these foods has only started to emerge in the last few decades. Although phytonutrients currently have no specific dietary intake recommendations, the U.S. Dietary Guidelines 2020-2025 recommend at least two daily servings for adults.Epidemiological studies have shown that the regular consumption of fruits is associated with decreased risk for many age-related chronic conditions including cardiovascular and certain eye diseases. However, epidemiological data is observational and does not inform about cause-and-effect relationships. Cellular, animal and a limited number of human studies provide intriguing evidence regarding the potential health benefits of certain classes of phytonutrients, for instance, the protective effects of carotenoids on age-related macular degeneration and flavanols on vascular diseases. However, more clinical studies are needed to better clarify these relationships. This dissertation explores the role of select phytonutrient-rich fruits on two aspects of the aging process. Mango is a tropical fruit that has been used in traditional remedies in multiple tropical regions worldwide. Based on its use history and unique polyphenol profile, the fruit may be useful to support cardiovascular health. Goji berry has been used in traditional Chinese medicine for more than two thousand years for its “eye-brightening”. Chapter I summarizes the evidence about mango and goji berry, as well as blueberry and cocoa, as phytonutrient-rich fruits with potential cardiovascular and eye health benefits. Chapter II is a published clinical trial that investigated the effects of dried goji berry intake on macular pigment optical density and skin carotenoids in healthy middle-aged individuals. Chapter III explores the role of mango intake on markers related to cardiovascular function in postmenopausal women. Chapter IV is a detailed review about the role of lutein and zeaxanthin in age-related macular degeneration, the importance of these two carotenoids in maternal and infant health and concludes with a focus on goji berries as a potential dietary source to benefit eye health. Finally, a summary of this work and a discussion about future research directions is presented in Chapter V.

The role of nutrition in dermatology has been investigated for a long time, with a history of research focused on the effects of nutritional disorders on the skin. Some classic examples include pellagra, scurvy, and acrodermatitis enteropathica. Although these conditions have been mainly eradicated from developed countries due to fortification of food with the essential nutrients of concern or supplementation upon early detection, they can still be found among individuals or communities who are not receiving adequate nutrition due to factors such as economic instability, alcoholism, or eating disorders. As skin diseases caused by nutrition deficiencies become under control, current research focuses on managing dermal disorders such as dermatitis and acne, or promoting esthetics by decreasing wrinkles and hyperpigmentation as well as increasing hydration, collagen, and elasticity. Epidemiological studies suggest that a diet pattern rich in plant-based foods such as fruits and vegetables is associated with improved skin esthetics, such as fewer wrinkles, and lowers the risk of dermatological disorders. Plant-based foods are typically rich in bioactive compounds such as carotenoids, vitamins, and polyphenols that provide oxidant defense, protect against DNA damage and promote structural integrity to the skin. Deficiencies of select micronutrients such as vitamin A, C, E, and K have also been associated with certain skin disorders such as thickening of the skin, poor wound healing, and dermatitis. Unlike health conditions such as cardiovascular disease and diabetes, official dietary recommendations for specific skin disorders or esthetic concerns do not currently exist. The 2020 – 2025 Dietary Guidelines for Americans recommend consuming whole fruits and a variety of vegetables, with specific reference amounts for those with dark green, red, and orange colors, which are typically rich in carotenoids. This general recommendation aligns with the epidemiological studies that suggest beneficial effects to the skin by adopting a dietary pattern that consists of more plant-based foods. However, each fruit and vegetable has a unique nutrition profile and may elicit different skin benefits. This dissertation aimed to explore and understand the benefits of different plant-based food consumption on the skin. A particular emphasis was placed on mango, a tropical fruit that is widely consumed, and its relation to skin and inflammation. Chapter I provides some historical background on nutrition and skin, contextual information on the structure and functions of the skin, as well as a literature review of the reported effects of dietary carotenoids, vitamins, and polyphenols that can be found in mango on skin health and their potential mechanisms. The promising effects of mango intake led to the development of a study as detailed in Chapter II, which is a published manuscript that reported on a clinical trial that investigated the effects of fresh-frozen mango fruit intake on facial wrinkles in the lateral canthi and erythema in the cheeks of postmenopausal women with fair to beige skin tones. Chapter III is a manuscript that will be submitted for publication that reviewed the current evidence for consumption of plant-based foods and extracts, including fruits, vegetables, nuts, and legumes, on skin protection assessing parameters related to collagen, elasticity, erythema, hydration, roughness, and wrinkle. The narrative review focused on clinical dietary interventions with an aim to enable dietitians to provide better dietary recommendations with regards to select dermatological concerns. Chapter IV discussed the role of inflammatory markers on cardiovascular health and describes a study that investigated the effects of mango intake on endothelial function and pro-inflammatory markers. Appendix A is an accepted manuscript that described the development, utilization, and efficiency of a nutrition education game that aimed to elicit and reinforce healthier snack choices in children aged 9 to 13 years old. Appendix B details a newly funded proposed study to investigate the effects of mango intake on wrinkles and other skin measurements and changes in the gut microbiome by comparing it to a control group. In part, to confirm the findings from the study reported in Chapter II as the lack of a control group was a major limitation. Finally, a summary of this work and a discussion on future research directions will be presented in the Perspectives and Conclusions section.

The concept of food as medicine has existed for centuries. The focus of this dissertation is on plant-based functional foods that contain unique bioactive compounds with properties beyond basic nutrition. The health benefits of plant-based food consumption are supported by large epidemiological studies and randomized controlled trials demonstrating that the intake of fruits, vegetables, and whole grains are inversely associated with the rate of chronic disease morbidity and mortality. Two functional foods, sorghum and red wine, were studied. Chapter I provides a historical overview on the use of food as medicine and the application to modern times, with an emphasis on sorghum and red wine. Chapter II presents three probe studies that detail the postprandial plasma amino acid and glucose responses in healthy adult men following the intake of extruded or conventional sorghum flour. Chapter III explores the effects of Hokkaido Zweigelt red wines from different vintage years on cardiovascular health outcomes in healthy adult men. Chapter IV reviews the results of clinical research studies on red wine and vascular health, discussing factors that contribute to variable results, and proposes considerations for future studies. Chapter V provides perspectives and insights for future clinical nutrition research. Additionally, Appendix A describes the role of strawberries for weight management in adolescents and offers dietary recommendations. Appendix B summarizes the results of clinical studies with fruits, vegetables, nuts, and legumes on skin health outcomes. Taken together, the body of work emphasizes the importance of plant-based functional foods as key elements to support health promotion and disease prevention.