Vitamin D Moderators and Supplementation Outcomes

Abstract

Abstract Robyn L. Havens Vitamin D Moderators and Supplementation Outcomes (Under the direction of Dr. Elizabeth NeSmith) Vitamin D insufficiency is a global health concern affecting approximately 1 billion people, including about one third of the American population. Vitamin D insufficiency promotes the development of chronic diseases. The people most at risk for developing chronic diseases from vitamin D insufficiency are those individuals in the vulnerable populations who experience poor health outcomes. Currently, researchers and clinicians disagree as to the recommended daily allowance and therapeutic range supporting sufficient serum vitamin D concentrations. To provide data to resolve this disagreement, the objectives of this secondary analysis were to determine if age, sex, and body mass index were moderators of serum vitamin D concentration and if varying dosages of vitamin D supplementation affected serum interleukin-6 concentrations. The data records of 60 healthy male and female African American participants were examined who were aged 13-45 years, categorized as overweight or obese, and exhibited a baseline serum vitamin D concentration ≤ 50 nmol/L. The participants were randomized into four treatment groups for the original study: 1) a control group that received a placebo; (2) a group that received monthly supervised doses of 18,000 IU (equivalent to 600 IU/day); (3) a group that received monthly supervised doses of 60,000 IU (equivalent to 2,000 IU/day); and (4) a group that received monthly supervised doses of 120,000 IU (equivalent to 4,000 IU/day). After 16 weeks of vitamin D supplementation, the only statistically significant interaction found was with sex as a moderating variable despite the small sample size of men. No other significant interactions were found, including no interaction with vitamin D supplementation and interleukin-6. Despite lacking statistical significance, the data results suggested that the 2,000 or 4,000 IU/day dosages of vitamin D supplementation was needed for the overweight/obese African American participants to achieve a sufficient serum vitamin D concentration > 50 nmol/L as recommended in the 2011 Institute of Medicine report. These results also suggest that the overweight/obese, African American adolescents and adults needed much more vitamin D supplementation than the 600 IU/day recommended by National Institute of Health researchers. Lastly, the findings suggest that the national clinical guidelines published by the Endocrine Society may warrant revision to at least 2,000 IU/day to be effective for individuals in vulnerable populations. Future research is needed to further elucidate the role vitamin D plays in maintaining overall good health and the benefits of vitamin D supplementation. Keywords: vitamin D, vitamin D insufficiency, vitamin D supplementation, age, sex, body mass index, interleukin-6, vulnerable populations conceptual model