Vitamin D Supplementation for Adults With Neurofibromatosis Type 1 (NF1)

This clinical trial is conducted by one of 4 locations; University of British Columbia (Vancouver, CA), University of Utah (Salt Lake City, UT, USA), University of Cincinnati (Cincinnati, OH, USA), and University of Hamburg (Hamburg, Germany). Adults with NF1 have a higher risk of osteopenia and osteoporosis, a condition of low bone density that can lead to fragile bones and bone breakage. People with NF1 also have lower vitamin D levels than unaffected individuals. Vitamin D is important for normal bone health, but studies to improve bone health by vitamin D supplementation in people with NF1 have not been tried. The purpose of this study is to treat adults with NF1 who have insufficient serum vitamin D levels with 2 different doses of vitamin D supplementation to determine if vitamin D supplementation ameliorates the usual loss of bone mineral density over 2 years.