Vitamin D3 Supplementation Pilot Study

Vitamin D deficiency/insufficiency is common throughout the lifespan, and across all race
and ethnic groups. The American Academy of Pediatrics (AAP) recently recommended
supplementation dose to 400 international units (IU) daily in all children. These
recommendations target rickets prevention, but address neither the vitamin D supplementation
necessary to optimize bone health nor the nontraditional vitamin D roles in immune disease,
insulin resistance, muscle function, and cardiovascular disease (CVD). Moreover, the AAP
recommendation noted that it had little pediatric data upon which to base guidelines. The
Institute of Medicine also recently published Dietary Reference Intakes for Calcium and
Vitamin D: the estimated average requirement in children and adults was set at 400(IU)
daily and the recommend dietary allowance was set at 600 IU daily. Data on outcomes and
supplementation levels in African Americans (a population at particular risk for vitamin D
deficiency) and across pediatric age ranges and body habitus types, are lacking. The Vitamin
D supplementation requirement in obese, African American adolescents is particularly
problematic since obesity is associated with 1) lower circulating vitamin D levels (25OHD)
and 2) insulin resistance. This pilot study will examine the effect of vitamin D
supplementation upon 25OHD, the serum marker of vitamin D status, in obese, African American
adolescents with vitamin D deficiency. Subjects will be randomized to receive
cholecalciferol 1000 IU or 5000 IU daily for 3 months. Serum 25OHD, parathyroid hormone,
glucose, insulin, CVD risk markers, and measures of muscle function and pain will be
obtained at baseline and post-treatment. This pilot study will provide data on serum 25OHD
responses to vitamin D at doses more likely to meaningfully impact 25OHD than the current
American Academy of Pediatrics (AAP) supplementation guideline. Responses to supplementation
can then inform future clinical trials aimed at addressing outcomes of vitamin D replacement
on insulin sensitivity and CVD risk in obese adolescents.

Inclusion Criteria:

- African American

- Obese [body mass index (BMI) greater than or equal to 95th percentile for age and
sex]

- Pubertal (Tanner Stage greater than 1)

- 25OHD less than 20 ng/mL (for treatment phase); if 25OHD is greater than or equal
to 20 ng/mL, only baseline data will be obtained.

- Committed to adherence to supplementation and study completion

Exclusion Criteria:

- Pregnancy

- Chronic medical conditions or medications use that can affect growth, nutrition, bone
health, vitamin D metabolism, glucose, or insulin sensitivity

- Known history of hypercalcemia or hypercalciuria

- Non-English speaking, as assessments are available only in English