Doctoral Dissertation Research: Impacts of dietary fat type on energy gain in the human holobiont

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Nutritional and energetic models of human metabolism assume that all dietary fats have the same caloric value. However, recent developments in gut microbiome research have challenged this view, with gut microbial communities shifting in response to different fat-rich diets, and the resulting gut microbiota differentially impacting energy gain. This dissertation project will examine the role of dietary fat types on energy gain from a human holobiont perspective, which interrogates both host and microbial mechanisms of energy harvest from different dietary fat sources. By assessing the impact of dietary fat type on host-microbial interactions, the investigators aim to better understand the process of dietary fat metabolism in ancestral and modern humans, to challenge traditional models of the isocaloric nature of fats, and to gain insight into associations between dietary fat intake and increasing rates of metabolic disease in industrial populations. Apart from contributing to the peer-reviewed scientific literature, this research will facilitate undergraduate research opportunities, particularly for women and underrepresented minorities in science, who presently comprise 80% of the laboratory research staff. In addition, through connections with the Harvard T.H. Chan School of Public Health and the Harvard Museums of Science and Culture, the investigators have committed to contributing to programs that make science accessible for a broad public audience. The trillions of microbes that reside in the human gut are now understood to play important roles in digestion and energy regulation. However, to date, models of past and present human energy budgets have not considered the microbial contributions to energy harvested from diet. In this research, the investigators will probe mechanisms of dietary fat metabolism that involve both host and microbial processes, evaluating the impacts of different dietary fats on host energy budget, intestinal fat absorption and inflammation, gut microbial composition, and direct gut microbial contributions to host energy status. To address these processes, the investigators will use conventional and germ-free murine models, which are routinely used for studying the effects of microbial community shifts on human physiology. This research will clarify the role that different dietary fats have played in the evolution of human energy metabolism, and will suggest new pathways for targeting the high and rising rates of obesity, type II diabetes, and other metabolic diseases in the industrialized world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.