Doctoral Dissertation Research: More than just sun and skin: Investigating the social and developmental determinants of vitamin D production

Recent discoveries in vitamin D research indicate that vitamin D is a necessary component to several organs and tissues. Historically, anthropological research has focused on the adaptive significance of skin color to minimize the harmful effects of exposure to ultraviolet rays while maintaining vitamin D production. While foundational in biological anthropology, unanswered questions remain regarding the developmental and environmental factors that shape vitamin D production within populations, in a single generation. For example, within populations, gender, season of birth, time spent outdoors, urbanicity and socioeconomic factors all contribute to patterns of sun exposure, and therefore levels of vitamin D. Furthermore, research indicates that vitamin D deficiency is rampant across the globe. Data from the Philippines, a tropical country, will be used to assess the impact of vitamin D among people in the Cebu Longitudinal Health and Nutrition Survey in the Philippines. Vitamin D assays will be performed from whole blood samples from participants (ages 20-22 years) to determine circulating vitamin D levels. Vitamin D will then be analyzed in conjunction with already existing DNA methylation data from the same participant samples. DNA methylation is a mechanism through which environments during development can regulate genome activity through the addition of methyl groups to CpG dinucleotides. Socio-cultural factors such as gender, season of birth, time spent outdoors, urbanicity and socioeconomic factors will then be evaluated as predictors of methylation in the vitamin D receptor gene (VDR) and four vitamin D metabolism enzyme genes (CYP2R1, CYP24A1, CYP27A1, CYP27B1) to better understand how vitamin D deficiency in populations in urbanizing tropical climates is affected by socio-cultural dynamics. Combining biocultural anthropology with epigenetics, this project will address three specific aims: (1) Investigate the socio-cultural factors that predict circulating serum vitamin D production in young adults, (2) Investigate environments in infancy and childhood as predictors of vitamin D production in young adulthood, and (3) Investigate methylation of vitamin D receptor genes as a potential mediator of the association between environmental exposures and vitamin D production.