title: Effects of Vitamin D Supplementation on C-peptide and 25-hydroxyvitamin D Concentrations at 3 and 6 Months.
abstract: The link between African-Americans' disproportionate rates of diabetes, obesity and vitamin D deficiency may be marked by C-peptide as an indicator of insulin secretion. We hypothesize that vitamin D supplementation will increase C-peptide, a marker of insulin secretion. During 3 winters from 2007-2010, 328 healthy African-Americans (median age, 51 years) living in Boston, MA were randomized into a 4-arm, double-blind trial for 3 months of placebo, 1000, 2000, or 4000 IU of vitamin D3. The differences in non-fasting C-peptide between baseline and 3 months were -0.44 ng/mL for those receiving placebo, -0.10 ng/mL for those receiving 1000 IU/d, 0 ng/mL for those receiving 2000 IU/d, 1.24 ng/mL for those receiving 4000 IU/d (C-peptide increased 0.42 ng/mL for each additional 1000 IU/d of vitamin D3, p < 0.001). Vitamin D supplementation increased C-peptide in overweight African-Americans and may be compatible with other recommendations for diabetes prevention and management including weight loss and increased physical activity.
authors.affiliation: 1] Division of Preventive Medicine, Brigham and Women's Hospital, Boston, MA [2] Harvard Medical School, Boston, MA.
authors.forename: Paulette D
authors.initials: PD
authors.lastname: Chandler
authors.affiliation: 1] Harvard Medical School, Boston, MA [2] Departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston, MA [3] Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA.
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
authors.affiliation: Department of Epidemiology and Biostatistics, College of Human Medicine, Michigan State University, East Lansing, MI.
authors.forename: Jamil B
authors.initials: JB
authors.lastname: Scott
authors.affiliation: Department of Psychology and Neuroscience, Duke University, Durham, NC.
authors.forename: Gary G
authors.initials: GG
authors.lastname: Bennett
authors.affiliation: 1] Harvard Medical School, Boston, MA [2] Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Kimmie
authors.initials: K
authors.lastname: Ng
authors.affiliation: 1] Harvard Medical School, Boston, MA [2] Division of Gastroenterology, Massachusetts General Hospital, Boston, MA.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
authors.affiliation: Division of Pediatrics, Medical University of South Carolina, Charleston, SC.
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Hollis
authors.affiliation: 1] Harvard Medical School, Boston, MA [2] Division of Laboratory Medicine, Children's Hospital of Boston, MA.
authors.forename: Nader
authors.initials: N
authors.lastname: Rifai
authors.affiliation: 1] Harvard Medical School, Boston, MA [2] Center for Community-Based Research, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Emmons
authors.affiliation: 1] Harvard Medical School, Boston, MA [2] Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fuchs
authors.affiliation: Department of Surgery, Division of Public Health Sciences, Washington University School of Medicine, St. Louis, MO.
authors.forename: Bettina F
authors.initials: BF
authors.lastname: Drake
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D002096:C-Peptide / Q000097:blood*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013997:Time Factors; D014807:Vitamin D / Q000008:administration & dosage* / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D002096:C-Peptide; D014807:Vitamin D; C104450:25-hydroxyvitamin D