A Prospective Trial on the Effects of Vitamin D Supplementation in Collegiate Swimmers and Divers

The investigators plan to recruit from approximately 45 male and female University of Kentucky Swimmers and Divers, at least 18 years of age in August 2011. Approximately equal numbers of men and women will be recruited. The entire athletic team(s) will be recruited. With a conservative dropout rate of 30%, the investigators final sample size should be approximately 22 participants (per group).Following baseline measures, participants will be randomized to one of two groups (Vitamin D 4000 IU or Placebo control) and monitored over the course of their athletic season. Measurements will be repeated at Midpoint (3 months) and Endpoint (6 months).

Participants will have no recent history of Vitamin D supplementation beyond what is normally found in a multivitamin (400 IUs).

Following the informed consent process a medical history and Vitamin D questionnaire (screenings), and urine pregnancy test (for female athletes) will be administered prior to more invasive baseline testing procedures (blood draw and DXA). A blood draw will then be conducted at baseline, midpoint and endpoint. Collected blood for the purposes of this study will assess Vitamin D status (25(OH)D), parathyroid hormone, ionized calcium, bone turnover markers, and inflammatory cytokines. A Vitamin D lifestyle questionnaire will be administered at all 3 time points and incidence of illness and injury will be documented over 6 months following randomization. DXA measures will only occur at Baseline and Endpoint.

Inclusion criteria

• University of Kentucky Swimmers and Divers, at least 18 years old.
• No recent history of Vitamin D supplementation beyond 400IU

Exclusion criteria

• hormone replacement therapy,
• high dose Vitamin D supplementation,
• history of renal disease or kidney stones,
• organ transplantation,
• sarcoidosis,
• parathyroid disease,
• history of high blood calcium levels.