Serum 1,25-dihydroxy vitamin D is inversely associated with body mass index.
BACKGROUND
Based on in vitro studies, it has been hypothesized that 1,25-dihydroxy vitamin D (1,25-vit D) may promote weight gain in humans, but previous studies have demonstrated conflicting results regarding the association between serum 1,25-vit D and body mass index (BMI).


OBJECTIVE
To evaluate the relation between serum 1,25-vit D and BMI.


METHODS
Two thousand one hundred and eighty-seven subjects, recruited from a metabolic and medical lifestyle management clinic, were included in a cross-sectional study. BMI, 25-hydroxy vitamin D (25-OH-vit D) and 1,25-vit D were measured. The cohort was divided according to BMI in five groups (<25, 25-29.9, 30-34.9, 35-39.9 and >39.9 kg/m(2)). Statistical analyses were performed with multiple linear regression models. Age and gender were used as explanatory covariates.


RESULTS
With increasing BMI group, there was a significant decrease in both serum 25-OH-vit D and 1,25-vit D (P<0.001). Those with BMI >39.9 kg/m(2) had 24% lower serum 25-OH-vit D levels and 18% lower 1,25-vit D levels than those with BMI <25 kg/m(2).


CONCLUSIONS
There is an inverse association between BMI and the serum levels of 25-OH-vit D and 1,25-vit D. This makes it highly unlikely that high levels of circulating 1,25-vit D contribute to the development of obesity.
Konradsen
Steinar
S
Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway.
Ag
Harald
H
Lindberg
Fedon
F
Hexeberg
Sofie
S
Jorde
Rolf
R
D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D012737:Sex Factors; D013851:Thinness / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D