Contributions of Dietary Vitamin D, Weight Status, and Skin Color to Vitamin D Status and Adherence to Vitamin D Supplements in At-Risk Youth.
Au, Lauren.
2017-04-14T13:31:23.345Z
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Abstract: Vitamin D is an essential nutrient for bone growth and development in children. In addition to its skeletal effects, vitamin D may also reduce risks for a variety of diseases that can affect children, including upper respiratory infections, autoimmune diseases, and cardiometabolic diseases. Most circulating 25-hydroxyvitamin D (25OHD) comes from exposure to UVB rays in natural sunlight. ... read moreHowever, excess adiposity, dark skin pigmentation, and other factors can impair this process. Under such circumstances, dietary vitamin D becomes critically important for maintaining an adequate serum concentration of this vitamin. The overall objectives of this dissertation were to determine how vitamin D is affected by weight status, race/ethnicity, and skin pigmentation and to understand the factors that promote adherence to vitamin D supplementation in children who are at risk of deficiency. Specifically, the following three Study Aims were addressed: 1) to examine the influences of weight status and race/ethnicity on the association of total vitamin D intake with serum 25OHD in U.S. children; 2) to determine the extent to which differences in skin color explain racial/ethnic differences in serum 25OHD among schoolchildren; and 3) to examine the determinants of adherence to vitamin D supplementation in schoolchildren at-risk for deficiency. These associations were examined cross-sectionally through data collected from that National Health and Nutrition Examination Survey (NHANES) 2005-2006 and the Daily D Health Study (DDHS), a vitamin D supplementation study of 4th-8th grade schoolchildren from racially diverse communities in the northeastern U.S. For Study Aim 1, vitamin D intakes and serum 25OHD were estimated in a national sample of 3,310 children and adolescents (ages 1-18 years) from the 2005-2006 NHANES. The majority (75%) of U.S. children failed to meet current Estimated Average Requirements (EAR). Overweight/obese children who failed to meet the EAR were five times more likely to be at risk for inadequate 25OHD than children who met it (P<0.001). Black children with intakes below the EAR were nearly four times more likely to be at risk for inadequate 25OHD than children who met the EAR (P<0.01). Study Aim 2 explored the relationship between race/ethnicity and genetic skin color with serum 25OHD in a sample of 307 children (ages 9-15 years) from the DDHS. Race/ethnicity and skin color were similarly predictive of 25OHD; however race/ethnicity explained additional variability in 25OHD beyond skin color in this population (P=0.03). Study Aim 3 examined the determinants of adherence to vitamin D supplementation in a sub-sample of 256 child and parent pairs from the DDHS. Adherence was higher when parents took vitamin D-containing supplements (7% higher, P=0.008) and also with combined child and parent administration of the supplement compared to child only (9% higher, P=0.03), but was largely unrelated to specific health beliefs. In conclusion, overweight/obese and black U.S. children who were not consuming the EAR were more likely to be at risk for inadequate 25OHD. Our findings also provide the first evidence that race/ethnicity captures additional variability in 25OHD beyond genetic skin color. Finally, promoting parental involvement may be a practical solution for health professionals aiming to improve supplement adherence in at-risk youth.
Thesis (Ph.D.)--Tufts University, 2013.
Submitted to the Dept. of Food Policy & Applied Nutrition.
Advisor: Jennifer Sacheck.
Committee: Susan Harris, Johanna Dwyer, and Paul Jacques.
Keywords: Nutrition, and Epidemiology.read less - ID:
- c247f4637
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