With avoidance of sunlight exposure due to lifestyle changes and concerns regarding skin cancer and the resultant widespread use of sunscreen, very few Americans are meeting their needs for vitamin D either through skin photosynthesis or dietary intake. A study published by the Centers for Disease Control (CDC) and our laboratory at the Medical University of South Carolina (MUSC) revealed that 42% of African American women in their childbearing years exhibited a deficiency of D vitamin (hypovitaminosis D) (1). Using new guidelines of optimal vitamin D levels, more than 90% of African American women now suffer from vitamin D deficiency (2). Science News (October 2004) called vitamin D deficiency a "silent epidemic" in America, with no group unaffected (3). Deficiency during pregnancy has profound effects on the developing fetus. Vitamin D deficiency affects other systems besides bones: it is associated with later, lifelong sequelae, with notable increased risk of autoimmune diseases such as rheumatoid arthritis (4), multiple sclerosis (5,6), type I diabetes (7,8), and certain cancers (7,9-14). Prevention and intervention studies only recently have been undertaken (3). A reexamination of dietary vitamin D requirements of various vulnerable populations in the U.S. is desperately needed (2,3). As a representative community with a diverse population, Eau Claire Cooperative Health Centers in South Carolina (ECCHC) serves a large percentage of African American as well as Caucasian and Hispanic women and children considered to be at high risk for vitamin D deficiency. ECCHC has eight clinics providing 1o care services to patients with special emphasis on Pediatric and OB/GYN services. Defining the prevalence of vitamin D deficiency in this patient population and the optimal vitamin D supplementation strategies for these women and their infants will become the prototype for recommendations applicable to other communities throughout the U.S.

In Specific Aim 1, the vitamin D status of a cross-sectional sample of 1000 pregnant women presenting at ECCHC for their prenatal care will be determined by measuring serum calcium, phosphorus, intact parathyroid hormone (iPTH), 25(OH)D, the nutritional marker of vitamin D as a function of ethnicity. Maternal health characteristics, skin pigmentation (using reflectance spectrophotometry), dietary characteristics (using an established food frequency questionnaire), and lifestyle profiles (using standardized questionnaires) will be ascertained as well. Any deficiency noted will lead to specific recommendations for vitamin D supplementation by the research team, with standardized strategies to monitor status following initiation of supplementation in Specific Aim 2. Based on extensive preliminary data, a supplementation regimen will be implemented and its efficacy in achieving optimal vitamin D status in these women tested in Aim 2: women within three racial groups (African American, Hispanic and Caucasian) will be stratified into two groups by their initial 25(OH)D level: Group 1, \<32 ng/mL (less than optimal vitamin D status) and Group 2, ≥32 ng/mL (optimal vitamin D status). Based on our ongoing NIH study of pregnant women, each group will be randomized to receive one of two doses starting at 13 weeks' gestation: 2,000 or 4,000 IU vitamin D3/day after a universal one-month 2,000 IU/day dosing run-in period at 12 weeks' balanced by race/ethnicity. The randomization schema allows determination of both efficacy and safety for those deficient and those replete at entry into the study as a function of race/ethnicity and season.

Anticipated Results and Future Studies: We expect to observe vitamin D deficiency in a considerable percentage of the mothers and their newborn infants who receive care at ECCHC, especially those individuals with darker pigmentation. In Aims 1 \& 2, by determining the prevalence of vitamin D deficiency with each racial/ethnic group, we will establish guidelines for supplementation and health maintenance, and policy recommendations for the dietary recommended intake of vitamin D in the U.S. The results will allow us to implement specific dietary and/or medical interventions aimed at correcting hypovitaminosis D in the population in this study and other similar populations being served by the more than 1000 community health centers nationally.