Association of plasma vitamin D levels with adiposity in Hispanic and African Americans.
BACKGROUND
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](2)D) and measures of adiposity has not been well characterized in minority populations.


OBJECTIVE
The objective of the study was to examine the relationship between levels of 25[OH]D and 1,25[OH](2)D and measures of adiposity in Hispanic and African-Americans at baseline and on change in these measures over time.


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


METHODS
25[OH]D (nanograms per milliliter) and 1,25[OH](2)D (picograms per milliliter) were measured at baseline. Abdominal sc adipose tissue (SAT), visceral adipose tissue (VAT; both determined by computed tomography scan), and body mass index (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 visceral fat to sc fat ratio in African-Americans (P = 0.049) but not Hispanics. 1,25[OH](2)D 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, whereas 1,25[OH](2)D was inversely associated with SAT in Hispanics (P < 0.0001) and with visceral fat to sc fat ratio in African-Americans (P = 0.02). Adjusting for 25[OH]D attenuated these associations; 1,25[OH](2)D remained associated with BMI in both populations (P < 0.05) and with SAT (P = 0.004) in Hispanics. No significant associations between 5-yr change in adiposity and 25[OH]D or 1,25[OH](2)D 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 5-yr change in adiposity.
Young
Kendra A
KA
Colorado School of Public Health, University of Colorado Denver, 13001 East 17th Place, Aurora, Colorado 80045, USA.
Engelman
Corinne D
CD
Langefeld
Carl D
CD
Hairston
Kristen G
KG
Haffner
Steven M
SM
Bryer-Ash
Michael
M
Norris
Jill M
JM
D050153:Abdominal Fat / Q000378:metabolism; D050154:Adiposity; D000328:Adult; D001741:Black or African American; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006630:Hispanic or Latino; D006801:Humans; D050152:Intra-Abdominal Fat / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D