Context: Previous studies have suggested vitamin D insufficiency is associated with increased obesity; however, the relationship between 25-hydroxyvitamin D (25[OH]D) and 1,25-dihydroxyvitamin D (1,25[OH]₂D) and measures of adiposity has not been well characterized in minority populations.

Objective: Examine the relationship between levels of 25[OH]D and 1,25[OH]₂D and measures of adiposity in Hispanic and African Americans at baseline and on change in these measures over time.

Design and Setting: The Insulin Resistance Atherosclerosis (IRAS) Family Study examined 917 Hispanics and 439 African Americans at baseline and again 5.3 years later (n=1081 at follow-up).

Main Outcome Measure: 25[OH]D (ng/mL) and 1,25[OH] ₂D (pg/mL) were measured at baseline. Abdominal SAT and VAT (determined by CT scan), and BMI were measured at baseline and follow-up.

Results: 25[OH]D was inversely associated with BMI, VAT, and SAT in both populations at baseline (p<0.001). 25[OH]D was marginally inversely associated with baseline VSR in African Americans (p=0.049), but not in Hispanics. 1,25[OH]₂D was inversely associated with BMI (p<0.0001, p=0.002) and VAT (p=0.0005, p=0.012) in Hispanics and African Americans, respectively, while 1,25[OH]₂D was inversely associated with SAT in Hispanics (p<0.0001) and with VSR in African-Americans (p=0.02). Adjusting for 25[OH]D attenuated these associations; 1,25[OH]₂D remained associated with BMI in both populations (p<0.05), and with SAT (p=0.004) in Hispanics. No significant associations between 5 year change in adiposity and 25[OH]D nor 1,25[OH]₂D were seen.

Conclusions: Vitamin D levels were inversely associated with baseline BMI, SAT, and VAT in Hispanic and African Americans, but were not associated with five year change in adiposity.